/* i810_drv.h -- Private header for the Matrox g200/g400 driver -*- linux-c -*-
 * Created: Mon Dec 13 01:50:01 1999 by jhartmann@precisioninsight.com
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors: Rickard E. (Rik) Faith <faith@valinux.com>
 *	    Jeff Hartmann <jhartmann@valinux.com>
 *
 */

#ifndef _I810_DRV_H_
#define _I810_DRV_H_

/* General customization:
 */

#define DRIVER_AUTHOR		"VA Linux Systems Inc."

#define DRIVER_NAME		"i810"
#define DRIVER_DESC		"Intel i810"
#define DRIVER_DATE		"20030605"

/* Interface history
 *
 * 1.1   - XFree86 4.1
 * 1.2   - XvMC interfaces
 *       - XFree86 4.2
 * 1.2.1 - Disable copying code (leave stub ioctls for backwards compatibility)
 *       - Remove requirement for interrupt (leave stubs again)
 * 1.3   - Add page flipping.
 * 1.4   - fix DRM interface
 */
#define DRIVER_MAJOR		1
#define DRIVER_MINOR		4
#define DRIVER_PATCHLEVEL	0

typedef struct drm_i810_buf_priv {
	u32 *in_use;
	int my_use_idx;
	int currently_mapped;
	void *virtual;
	void *kernel_virtual;
	drm_local_map_t map;
} drm_i810_buf_priv_t;

typedef struct _drm_i810_ring_buffer {
	int tail_mask;
	unsigned long Start;
	unsigned long End;
	unsigned long Size;
	u8 *virtual_start;
	int head;
	int tail;
	int space;
	drm_local_map_t map;
} drm_i810_ring_buffer_t;

typedef struct drm_i810_private {
	struct drm_map *sarea_map;
	struct drm_map *mmio_map;

	drm_i810_sarea_t *sarea_priv;
	drm_i810_ring_buffer_t ring;

	void *hw_status_page;
	unsigned long counter;

	dma_addr_t dma_status_page;

	struct drm_buf *mmap_buffer;

	u32 front_di1, back_di1, zi1;

	int back_offset;
	int depth_offset;
	int overlay_offset;
	int overlay_physical;
	int w, h;
	int pitch;
	int back_pitch;
	int depth_pitch;

	int do_boxes;
	int dma_used;

	int current_page;
	int page_flipping;

	wait_queue_head_t irq_queue;
	atomic_t irq_received;
	atomic_t irq_emitted;

	int front_offset;
} drm_i810_private_t;

				/* i810_dma.c */
extern int i810_driver_dma_quiescent(struct drm_device * dev);
extern void i810_driver_reclaim_buffers_locked(struct drm_device * dev,
					       struct drm_file *file_priv);
extern int i810_driver_load(struct drm_device *, unsigned long flags);
extern void i810_driver_lastclose(struct drm_device * dev);
extern void i810_driver_preclose(struct drm_device * dev,
				 struct drm_file *file_priv);
extern void i810_driver_reclaim_buffers_locked(struct drm_device * dev,
					       struct drm_file *file_priv);
extern int i810_driver_device_is_agp(struct drm_device * dev);

extern struct drm_ioctl_desc i810_ioctls[];
extern int i810_max_ioctl;

#define I810_BASE(reg)		((unsigned long) \
				dev_priv->mmio_map->handle)
#define I810_ADDR(reg)		(I810_BASE(reg) + reg)
#define I810_DEREF(reg)		*(__volatile__ int *)I810_ADDR(reg)
#define I810_READ(reg)		I810_DEREF(reg)
#define I810_WRITE(reg,val)	do { I810_DEREF(reg) = val; } while (0)
#define I810_DEREF16(reg)	*(__volatile__ u16 *)I810_ADDR(reg)
#define I810_READ16(reg)	I810_DEREF16(reg)
#define I810_WRITE16(reg,val)	do { I810_DEREF16(reg) = val; } while (0)

#define I810_VERBOSE 0
#define RING_LOCALS	unsigned int outring, ringmask; \
                        volatile char *virt;

#define BEGIN_LP_RING(n) do {						\
	if (I810_VERBOSE)						\
		DRM_DEBUG("BEGIN_LP_RING(%d)\n", n);			\
	if (dev_priv->ring.space < n*4)					\
		i810_wait_ring(dev, n*4);				\
	dev_priv->ring.space -= n*4;					\
	outring = dev_priv->ring.tail;					\
	ringmask = dev_priv->ring.tail_mask;				\
	virt = dev_priv->ring.virtual_start;				\
} while (0)

#define ADVANCE_LP_RING() do {					\
	if (I810_VERBOSE) DRM_DEBUG("ADVANCE_LP_RING\n");	\
	dev_priv->ring.tail = outring;				\
	I810_WRITE(LP_RING + RING_TAIL, outring);		\
} while(0)

#define OUT_RING(n) do {						\
	if (I810_VERBOSE) DRM_DEBUG("   OUT_RING %x\n", (int)(n));	\
	*(volatile unsigned int *)(virt + outring) = n;			\
	outring += 4;							\
	outring &= ringmask;						\
} while (0)

#define GFX_OP_USER_INTERRUPT		((0<<29)|(2<<23))
#define GFX_OP_BREAKPOINT_INTERRUPT	((0<<29)|(1<<23))
#define CMD_REPORT_HEAD			(7<<23)
#define CMD_STORE_DWORD_IDX		((0x21<<23) | 0x1)
#define CMD_OP_BATCH_BUFFER  ((0x0<<29)|(0x30<<23)|0x1)

#define INST_PARSER_CLIENT   0x00000000
#define INST_OP_FLUSH        0x02000000
#define INST_FLUSH_MAP_CACHE 0x00000001

#define BB1_START_ADDR_MASK   (~0x7)
#define BB1_PROTECTED         (1<<0)
#define BB1_UNPROTECTED       (0<<0)
#define BB2_END_ADDR_MASK     (~0x7)

#define I810REG_HWSTAM		0x02098
#define I810REG_INT_IDENTITY_R	0x020a4
#define I810REG_INT_MASK_R	0x020a8
#define I810REG_INT_ENABLE_R	0x020a0

#define LP_RING			0x2030
#define HP_RING			0x2040
#define RING_TAIL		0x00
#define TAIL_ADDR		0x000FFFF8
#define RING_HEAD		0x04
#define HEAD_WRAP_COUNT		0xFFE00000
#define HEAD_WRAP_ONE		0x00200000
#define HEAD_ADDR		0x001FFFFC
#define RING_START		0x08
#define START_ADDR		0x00FFFFF8
#define RING_LEN		0x0C
#define RING_NR_PAGES		0x000FF000
#define RING_REPORT_MASK	0x00000006
#define RING_REPORT_64K		0x00000002
#define RING_REPORT_128K	0x00000004
#define RING_NO_REPORT		0x00000000
#define RING_VALID_MASK		0x00000001
#define RING_VALID		0x00000001
#define RING_INVALID		0x00000000

#define GFX_OP_SCISSOR         ((0x3<<29)|(0x1c<<24)|(0x10<<19))
#define SC_UPDATE_SCISSOR       (0x1<<1)
#define SC_ENABLE_MASK          (0x1<<0)
#define SC_ENABLE               (0x1<<0)

#define GFX_OP_SCISSOR_INFO    ((0x3<<29)|(0x1d<<24)|(0x81<<16)|(0x1))
#define SCI_YMIN_MASK      (0xffff<<16)
#define SCI_XMIN_MASK      (0xffff<<0)
#define SCI_YMAX_MASK      (0xffff<<16)
#define SCI_XMAX_MASK      (0xffff<<0)

#define GFX_OP_COLOR_FACTOR      ((0x3<<29)|(0x1d<<24)|(0x1<<16)|0x0)
#define GFX_OP_STIPPLE           ((0x3<<29)|(0x1d<<24)|(0x83<<16))
#define GFX_OP_MAP_INFO          ((0x3<<29)|(0x1d<<24)|0x2)
#define GFX_OP_DESTBUFFER_VARS   ((0x3<<29)|(0x1d<<24)|(0x85<<16)|0x0)
#define GFX_OP_DRAWRECT_INFO     ((0x3<<29)|(0x1d<<24)|(0x80<<16)|(0x3))
#define GFX_OP_PRIMITIVE         ((0x3<<29)|(0x1f<<24))

#define CMD_OP_Z_BUFFER_INFO     ((0x0<<29)|(0x16<<23))
#define CMD_OP_DESTBUFFER_INFO   ((0x0<<29)|(0x15<<23))
#define CMD_OP_FRONTBUFFER_INFO  ((0x0<<29)|(0x14<<23))
#define CMD_OP_WAIT_FOR_EVENT    ((0x0<<29)|(0x03<<23))

#define BR00_BITBLT_CLIENT   0x40000000
#define BR00_OP_COLOR_BLT    0x10000000
#define BR00_OP_SRC_COPY_BLT 0x10C00000
#define BR13_SOLID_PATTERN   0x80000000

#define WAIT_FOR_PLANE_A_SCANLINES (1<<1)
#define WAIT_FOR_PLANE_A_FLIP      (1<<2)
#define WAIT_FOR_VBLANK (1<<3)

#endif
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<a id='n408' href='#n408'>408</a>
<a id='n409' href='#n409'>409</a>
<a id='n410' href='#n410'>410</a>
<a id='n411' href='#n411'>411</a>
<a id='n412' href='#n412'>412</a>
<a id='n413' href='#n413'>413</a>
<a id='n414' href='#n414'>414</a>
<a id='n415' href='#n415'>415</a>
<a id='n416' href='#n416'>416</a>
<a id='n417' href='#n417'>417</a>
<a id='n418' href='#n418'>418</a>
<a id='n419' href='#n419'>419</a>
<a id='n420' href='#n420'>420</a>
<a id='n421' href='#n421'>421</a>
<a id='n422' href='#n422'>422</a>
<a id='n423' href='#n423'>423</a>
<a id='n424' href='#n424'>424</a>
<a id='n425' href='#n425'>425</a>
<a id='n426' href='#n426'>426</a>
<a id='n427' href='#n427'>427</a>
<a id='n428' href='#n428'>428</a>
<a id='n429' href='#n429'>429</a>
<a id='n430' href='#n430'>430</a>
<a id='n431' href='#n431'>431</a>
<a id='n432' href='#n432'>432</a>
<a id='n433' href='#n433'>433</a>
<a id='n434' href='#n434'>434</a>
<a id='n435' href='#n435'>435</a>
<a id='n436' href='#n436'>436</a>
<a id='n437' href='#n437'>437</a>
<a id='n438' href='#n438'>438</a>
<a id='n439' href='#n439'>439</a>
<a id='n440' href='#n440'>440</a>
<a id='n441' href='#n441'>441</a>
<a id='n442' href='#n442'>442</a>
<a id='n443' href='#n443'>443</a>
<a id='n444' href='#n444'>444</a>
<a id='n445' href='#n445'>445</a>
<a id='n446' href='#n446'>446</a>
<a id='n447' href='#n447'>447</a>
<a id='n448' href='#n448'>448</a>
<a id='n449' href='#n449'>449</a>
<a id='n450' href='#n450'>450</a>
<a id='n451' href='#n451'>451</a>
<a id='n452' href='#n452'>452</a>
<a id='n453' href='#n453'>453</a>
<a id='n454' href='#n454'>454</a>
<a id='n455' href='#n455'>455</a>
<a id='n456' href='#n456'>456</a>
<a id='n457' href='#n457'>457</a>
<a id='n458' href='#n458'>458</a>
<a id='n459' href='#n459'>459</a>
<a id='n460' href='#n460'>460</a>
<a id='n461' href='#n461'>461</a>
<a id='n462' href='#n462'>462</a>
<a id='n463' href='#n463'>463</a>
<a id='n464' href='#n464'>464</a>
<a id='n465' href='#n465'>465</a>
<a id='n466' href='#n466'>466</a>
<a id='n467' href='#n467'>467</a>
<a id='n468' href='#n468'>468</a>
<a id='n469' href='#n469'>469</a>
<a id='n470' href='#n470'>470</a>
<a id='n471' href='#n471'>471</a>
<a id='n472' href='#n472'>472</a>
<a id='n473' href='#n473'>473</a>
<a id='n474' href='#n474'>474</a>
<a id='n475' href='#n475'>475</a>
<a id='n476' href='#n476'>476</a>
<a id='n477' href='#n477'>477</a>
<a id='n478' href='#n478'>478</a>
<a id='n479' href='#n479'>479</a>
<a id='n480' href='#n480'>480</a>
<a id='n481' href='#n481'>481</a>
<a id='n482' href='#n482'>482</a>
<a id='n483' href='#n483'>483</a>
<a id='n484' href='#n484'>484</a>
<a id='n485' href='#n485'>485</a>
<a id='n486' href='#n486'>486</a>
<a id='n487' href='#n487'>487</a>
<a id='n488' href='#n488'>488</a>
<a id='n489' href='#n489'>489</a>
<a id='n490' href='#n490'>490</a>
<a id='n491' href='#n491'>491</a>
<a id='n492' href='#n492'>492</a>
<a id='n493' href='#n493'>493</a>
<a id='n494' href='#n494'>494</a>
<a id='n495' href='#n495'>495</a>
<a id='n496' href='#n496'>496</a>
<a id='n497' href='#n497'>497</a>
<a id='n498' href='#n498'>498</a>
<a id='n499' href='#n499'>499</a>
<a id='n500' href='#n500'>500</a>
<a id='n501' href='#n501'>501</a>
<a id='n502' href='#n502'>502</a>
<a id='n503' href='#n503'>503</a>
<a id='n504' href='#n504'>504</a>
<a id='n505' href='#n505'>505</a>
<a id='n506' href='#n506'>506</a>
<a id='n507' href='#n507'>507</a>
<a id='n508' href='#n508'>508</a>
<a id='n509' href='#n509'>509</a>
<a id='n510' href='#n510'>510</a>
<a id='n511' href='#n511'>511</a>
<a id='n512' href='#n512'>512</a>
<a id='n513' href='#n513'>513</a>
<a id='n514' href='#n514'>514</a>
<a id='n515' href='#n515'>515</a>
<a id='n516' href='#n516'>516</a>
<a id='n517' href='#n517'>517</a>
<a id='n518' href='#n518'>518</a>
<a id='n519' href='#n519'>519</a>
<a id='n520' href='#n520'>520</a>
<a id='n521' href='#n521'>521</a>
<a id='n522' href='#n522'>522</a>
<a id='n523' href='#n523'>523</a>
<a id='n524' href='#n524'>524</a>
<a id='n525' href='#n525'>525</a>
<a id='n526' href='#n526'>526</a>
<a id='n527' href='#n527'>527</a>
<a id='n528' href='#n528'>528</a>
<a id='n529' href='#n529'>529</a>
<a id='n530' href='#n530'>530</a>
<a id='n531' href='#n531'>531</a>
<a id='n532' href='#n532'>532</a>
<a id='n533' href='#n533'>533</a>
<a id='n534' href='#n534'>534</a>
<a id='n535' href='#n535'>535</a>
<a id='n536' href='#n536'>536</a>
<a id='n537' href='#n537'>537</a>
<a id='n538' href='#n538'>538</a>
<a id='n539' href='#n539'>539</a>
<a id='n540' href='#n540'>540</a>
<a id='n541' href='#n541'>541</a>
<a id='n542' href='#n542'>542</a>
<a id='n543' href='#n543'>543</a>
<a id='n544' href='#n544'>544</a>
<a id='n545' href='#n545'>545</a>
<a id='n546' href='#n546'>546</a>
<a id='n547' href='#n547'>547</a>
<a id='n548' href='#n548'>548</a>
<a id='n549' href='#n549'>549</a>
<a id='n550' href='#n550'>550</a>
<a id='n551' href='#n551'>551</a>
<a id='n552' href='#n552'>552</a>
<a id='n553' href='#n553'>553</a>
<a id='n554' href='#n554'>554</a>
<a id='n555' href='#n555'>555</a>
<a id='n556' href='#n556'>556</a>
<a id='n557' href='#n557'>557</a>
<a id='n558' href='#n558'>558</a>
<a id='n559' href='#n559'>559</a>
<a id='n560' href='#n560'>560</a>
<a id='n561' href='#n561'>561</a>
<a id='n562' href='#n562'>562</a>
<a id='n563' href='#n563'>563</a>
<a id='n564' href='#n564'>564</a>
<a id='n565' href='#n565'>565</a>
<a id='n566' href='#n566'>566</a>
<a id='n567' href='#n567'>567</a>
<a id='n568' href='#n568'>568</a>
<a id='n569' href='#n569'>569</a>
<a id='n570' href='#n570'>570</a>
<a id='n571' href='#n571'>571</a>
<a id='n572' href='#n572'>572</a>
<a id='n573' href='#n573'>573</a>
<a id='n574' href='#n574'>574</a>
<a id='n575' href='#n575'>575</a>
<a id='n576' href='#n576'>576</a>
<a id='n577' href='#n577'>577</a>
<a id='n578' href='#n578'>578</a>
<a id='n579' href='#n579'>579</a>
<a id='n580' href='#n580'>580</a>
<a id='n581' href='#n581'>581</a>
<a id='n582' href='#n582'>582</a>
<a id='n583' href='#n583'>583</a>
<a id='n584' href='#n584'>584</a>
<a id='n585' href='#n585'>585</a>
<a id='n586' href='#n586'>586</a>
<a id='n587' href='#n587'>587</a>
<a id='n588' href='#n588'>588</a>
<a id='n589' href='#n589'>589</a>
<a id='n590' href='#n590'>590</a>
<a id='n591' href='#n591'>591</a>
<a id='n592' href='#n592'>592</a>
<a id='n593' href='#n593'>593</a>
<a id='n594' href='#n594'>594</a>
<a id='n595' href='#n595'>595</a>
<a id='n596' href='#n596'>596</a>
<a id='n597' href='#n597'>597</a>
<a id='n598' href='#n598'>598</a>
<a id='n599' href='#n599'>599</a>
<a id='n600' href='#n600'>600</a>
<a id='n601' href='#n601'>601</a>
<a id='n602' href='#n602'>602</a>
<a id='n603' href='#n603'>603</a>
<a id='n604' href='#n604'>604</a>
<a id='n605' href='#n605'>605</a>
<a id='n606' href='#n606'>606</a>
<a id='n607' href='#n607'>607</a>
<a id='n608' href='#n608'>608</a>
<a id='n609' href='#n609'>609</a>
<a id='n610' href='#n610'>610</a>
<a id='n611' href='#n611'>611</a>
<a id='n612' href='#n612'>612</a>
<a id='n613' href='#n613'>613</a>
<a id='n614' href='#n614'>614</a>
<a id='n615' href='#n615'>615</a>
<a id='n616' href='#n616'>616</a>
<a id='n617' href='#n617'>617</a>
<a id='n618' href='#n618'>618</a>
<a id='n619' href='#n619'>619</a>
<a id='n620' href='#n620'>620</a>
<a id='n621' href='#n621'>621</a>
<a id='n622' href='#n622'>622</a>
<a id='n623' href='#n623'>623</a>
<a id='n624' href='#n624'>624</a>
<a id='n625' href='#n625'>625</a>
<a id='n626' href='#n626'>626</a>
<a id='n627' href='#n627'>627</a>
<a id='n628' href='#n628'>628</a>
<a id='n629' href='#n629'>629</a>
<a id='n630' href='#n630'>630</a>
<a id='n631' href='#n631'>631</a>
<a id='n632' href='#n632'>632</a>
<a id='n633' href='#n633'>633</a>
<a id='n634' href='#n634'>634</a>
<a id='n635' href='#n635'>635</a>
<a id='n636' href='#n636'>636</a>
<a id='n637' href='#n637'>637</a>
<a id='n638' href='#n638'>638</a>
<a id='n639' href='#n639'>639</a>
<a id='n640' href='#n640'>640</a>
<a id='n641' href='#n641'>641</a>
<a id='n642' href='#n642'>642</a>
<a id='n643' href='#n643'>643</a>
<a id='n644' href='#n644'>644</a>
<a id='n645' href='#n645'>645</a>
<a id='n646' href='#n646'>646</a>
<a id='n647' href='#n647'>647</a>
<a id='n648' href='#n648'>648</a>
<a id='n649' href='#n649'>649</a>
<a id='n650' href='#n650'>650</a>
<a id='n651' href='#n651'>651</a>
<a id='n652' href='#n652'>652</a>
<a id='n653' href='#n653'>653</a>
<a id='n654' href='#n654'>654</a>
<a id='n655' href='#n655'>655</a>
<a id='n656' href='#n656'>656</a>
<a id='n657' href='#n657'>657</a>
<a id='n658' href='#n658'>658</a>
<a id='n659' href='#n659'>659</a>
<a id='n660' href='#n660'>660</a>
<a id='n661' href='#n661'>661</a>
<a id='n662' href='#n662'>662</a>
<a id='n663' href='#n663'>663</a>
<a id='n664' href='#n664'>664</a>
<a id='n665' href='#n665'>665</a>
<a id='n666' href='#n666'>666</a>
<a id='n667' href='#n667'>667</a>
<a id='n668' href='#n668'>668</a>
<a id='n669' href='#n669'>669</a>
<a id='n670' href='#n670'>670</a>
<a id='n671' href='#n671'>671</a>
<a id='n672' href='#n672'>672</a>
<a id='n673' href='#n673'>673</a>
<a id='n674' href='#n674'>674</a>
<a id='n675' href='#n675'>675</a>
<a id='n676' href='#n676'>676</a>
<a id='n677' href='#n677'>677</a>
<a id='n678' href='#n678'>678</a>
<a id='n679' href='#n679'>679</a>
<a id='n680' href='#n680'>680</a>
<a id='n681' href='#n681'>681</a>
<a id='n682' href='#n682'>682</a>
<a id='n683' href='#n683'>683</a>
<a id='n684' href='#n684'>684</a>
<a id='n685' href='#n685'>685</a>
<a id='n686' href='#n686'>686</a>
<a id='n687' href='#n687'>687</a>
<a id='n688' href='#n688'>688</a>
<a id='n689' href='#n689'>689</a>
<a id='n690' href='#n690'>690</a>
<a id='n691' href='#n691'>691</a>
<a id='n692' href='#n692'>692</a>
<a id='n693' href='#n693'>693</a>
<a id='n694' href='#n694'>694</a>
<a id='n695' href='#n695'>695</a>
<a id='n696' href='#n696'>696</a>
<a id='n697' href='#n697'>697</a>
<a id='n698' href='#n698'>698</a>
<a id='n699' href='#n699'>699</a>
<a id='n700' href='#n700'>700</a>
<a id='n701' href='#n701'>701</a>
<a id='n702' href='#n702'>702</a>
<a id='n703' href='#n703'>703</a>
<a id='n704' href='#n704'>704</a>
<a id='n705' href='#n705'>705</a>
<a id='n706' href='#n706'>706</a>
<a id='n707' href='#n707'>707</a>
<a id='n708' href='#n708'>708</a>
<a id='n709' href='#n709'>709</a>
<a id='n710' href='#n710'>710</a>
<a id='n711' href='#n711'>711</a>
<a id='n712' href='#n712'>712</a>
<a id='n713' href='#n713'>713</a>
<a id='n714' href='#n714'>714</a>
<a id='n715' href='#n715'>715</a>
<a id='n716' href='#n716'>716</a>
<a id='n717' href='#n717'>717</a>
<a id='n718' href='#n718'>718</a>
<a id='n719' href='#n719'>719</a>
<a id='n720' href='#n720'>720</a>
<a id='n721' href='#n721'>721</a>
<a id='n722' href='#n722'>722</a>
<a id='n723' href='#n723'>723</a>
<a id='n724' href='#n724'>724</a>
<a id='n725' href='#n725'>725</a>
<a id='n726' href='#n726'>726</a>
<a id='n727' href='#n727'>727</a>
<a id='n728' href='#n728'>728</a>
<a id='n729' href='#n729'>729</a>
<a id='n730' href='#n730'>730</a>
<a id='n731' href='#n731'>731</a>
<a id='n732' href='#n732'>732</a>
<a id='n733' href='#n733'>733</a>
<a id='n734' href='#n734'>734</a>
<a id='n735' href='#n735'>735</a>
<a id='n736' href='#n736'>736</a>
<a id='n737' href='#n737'>737</a>
<a id='n738' href='#n738'>738</a>
<a id='n739' href='#n739'>739</a>
<a id='n740' href='#n740'>740</a>
<a id='n741' href='#n741'>741</a>
<a id='n742' href='#n742'>742</a>
<a id='n743' href='#n743'>743</a>
<a id='n744' href='#n744'>744</a>
<a id='n745' href='#n745'>745</a>
<a id='n746' href='#n746'>746</a>
<a id='n747' href='#n747'>747</a>
<a id='n748' href='#n748'>748</a>
<a id='n749' href='#n749'>749</a>
<a id='n750' href='#n750'>750</a>
<a id='n751' href='#n751'>751</a>
<a id='n752' href='#n752'>752</a>
<a id='n753' href='#n753'>753</a>
<a id='n754' href='#n754'>754</a>
<a id='n755' href='#n755'>755</a>
<a id='n756' href='#n756'>756</a>
<a id='n757' href='#n757'>757</a>
<a id='n758' href='#n758'>758</a>
<a id='n759' href='#n759'>759</a>
<a id='n760' href='#n760'>760</a>
<a id='n761' href='#n761'>761</a>
<a id='n762' href='#n762'>762</a>
<a id='n763' href='#n763'>763</a>
<a id='n764' href='#n764'>764</a>
<a id='n765' href='#n765'>765</a>
<a id='n766' href='#n766'>766</a>
<a id='n767' href='#n767'>767</a>
<a id='n768' href='#n768'>768</a>
<a id='n769' href='#n769'>769</a>
<a id='n770' href='#n770'>770</a>
<a id='n771' href='#n771'>771</a>
<a id='n772' href='#n772'>772</a>
<a id='n773' href='#n773'>773</a>
<a id='n774' href='#n774'>774</a>
<a id='n775' href='#n775'>775</a>
<a id='n776' href='#n776'>776</a>
<a id='n777' href='#n777'>777</a>
<a id='n778' href='#n778'>778</a>
<a id='n779' href='#n779'>779</a>
<a id='n780' href='#n780'>780</a>
<a id='n781' href='#n781'>781</a>
<a id='n782' href='#n782'>782</a>
<a id='n783' href='#n783'>783</a>
<a id='n784' href='#n784'>784</a>
<a id='n785' href='#n785'>785</a>
<a id='n786' href='#n786'>786</a>
<a id='n787' href='#n787'>787</a>
<a id='n788' href='#n788'>788</a>
<a id='n789' href='#n789'>789</a>
<a id='n790' href='#n790'>790</a>
<a id='n791' href='#n791'>791</a>
<a id='n792' href='#n792'>792</a>
<a id='n793' href='#n793'>793</a>
<a id='n794' href='#n794'>794</a>
<a id='n795' href='#n795'>795</a>
<a id='n796' href='#n796'>796</a>
<a id='n797' href='#n797'>797</a>
<a id='n798' href='#n798'>798</a>
<a id='n799' href='#n799'>799</a>
<a id='n800' href='#n800'>800</a>
<a id='n801' href='#n801'>801</a>
<a id='n802' href='#n802'>802</a>
<a id='n803' href='#n803'>803</a>
<a id='n804' href='#n804'>804</a>
<a id='n805' href='#n805'>805</a>
<a id='n806' href='#n806'>806</a>
<a id='n807' href='#n807'>807</a>
<a id='n808' href='#n808'>808</a>
<a id='n809' href='#n809'>809</a>
<a id='n810' href='#n810'>810</a>
<a id='n811' href='#n811'>811</a>
<a id='n812' href='#n812'>812</a>
<a id='n813' href='#n813'>813</a>
<a id='n814' href='#n814'>814</a>
<a id='n815' href='#n815'>815</a>
<a id='n816' href='#n816'>816</a>
<a id='n817' href='#n817'>817</a>
<a id='n818' href='#n818'>818</a>
<a id='n819' href='#n819'>819</a>
<a id='n820' href='#n820'>820</a>
<a id='n821' href='#n821'>821</a>
<a id='n822' href='#n822'>822</a>
<a id='n823' href='#n823'>823</a>
<a id='n824' href='#n824'>824</a>
<a id='n825' href='#n825'>825</a>
<a id='n826' href='#n826'>826</a>
<a id='n827' href='#n827'>827</a>
<a id='n828' href='#n828'>828</a>
<a id='n829' href='#n829'>829</a>
<a id='n830' href='#n830'>830</a>
<a id='n831' href='#n831'>831</a>
<a id='n832' href='#n832'>832</a>
<a id='n833' href='#n833'>833</a>
<a id='n834' href='#n834'>834</a>
<a id='n835' href='#n835'>835</a>
<a id='n836' href='#n836'>836</a>
<a id='n837' href='#n837'>837</a>
<a id='n838' href='#n838'>838</a>
<a id='n839' href='#n839'>839</a>
<a id='n840' href='#n840'>840</a>
<a id='n841' href='#n841'>841</a>
<a id='n842' href='#n842'>842</a>
<a id='n843' href='#n843'>843</a>
<a id='n844' href='#n844'>844</a>
<a id='n845' href='#n845'>845</a>
<a id='n846' href='#n846'>846</a>
<a id='n847' href='#n847'>847</a>
<a id='n848' href='#n848'>848</a>
<a id='n849' href='#n849'>849</a>
<a id='n850' href='#n850'>850</a>
<a id='n851' href='#n851'>851</a>
<a id='n852' href='#n852'>852</a>
<a id='n853' href='#n853'>853</a>
<a id='n854' href='#n854'>854</a>
<a id='n855' href='#n855'>855</a>
<a id='n856' href='#n856'>856</a>
<a id='n857' href='#n857'>857</a>
<a id='n858' href='#n858'>858</a>
<a id='n859' href='#n859'>859</a>
<a id='n860' href='#n860'>860</a>
<a id='n861' href='#n861'>861</a>
<a id='n862' href='#n862'>862</a>
<a id='n863' href='#n863'>863</a>
<a id='n864' href='#n864'>864</a>
<a id='n865' href='#n865'>865</a>
<a id='n866' href='#n866'>866</a>
<a id='n867' href='#n867'>867</a>
<a id='n868' href='#n868'>868</a>
<a id='n869' href='#n869'>869</a>
<a id='n870' href='#n870'>870</a>
<a id='n871' href='#n871'>871</a>
<a id='n872' href='#n872'>872</a>
<a id='n873' href='#n873'>873</a>
<a id='n874' href='#n874'>874</a>
<a id='n875' href='#n875'>875</a>
<a id='n876' href='#n876'>876</a>
<a id='n877' href='#n877'>877</a>
<a id='n878' href='#n878'>878</a>
<a id='n879' href='#n879'>879</a>
<a id='n880' href='#n880'>880</a>
<a id='n881' href='#n881'>881</a>
<a id='n882' href='#n882'>882</a>
<a id='n883' href='#n883'>883</a>
<a id='n884' href='#n884'>884</a>
<a id='n885' href='#n885'>885</a>
<a id='n886' href='#n886'>886</a>
<a id='n887' href='#n887'>887</a>
<a id='n888' href='#n888'>888</a>
<a id='n889' href='#n889'>889</a>
<a id='n890' href='#n890'>890</a>
<a id='n891' href='#n891'>891</a>
<a id='n892' href='#n892'>892</a>
<a id='n893' href='#n893'>893</a>
<a id='n894' href='#n894'>894</a>
<a id='n895' href='#n895'>895</a>
<a id='n896' href='#n896'>896</a>
<a id='n897' href='#n897'>897</a>
<a id='n898' href='#n898'>898</a>
<a id='n899' href='#n899'>899</a>
<a id='n900' href='#n900'>900</a>
<a id='n901' href='#n901'>901</a>
<a id='n902' href='#n902'>902</a>
<a id='n903' href='#n903'>903</a>
<a id='n904' href='#n904'>904</a>
<a id='n905' href='#n905'>905</a>
<a id='n906' href='#n906'>906</a>
<a id='n907' href='#n907'>907</a>
<a id='n908' href='#n908'>908</a>
<a id='n909' href='#n909'>909</a>
<a id='n910' href='#n910'>910</a>
<a id='n911' href='#n911'>911</a>
<a id='n912' href='#n912'>912</a>
<a id='n913' href='#n913'>913</a>
<a id='n914' href='#n914'>914</a>
<a id='n915' href='#n915'>915</a>
<a id='n916' href='#n916'>916</a>
<a id='n917' href='#n917'>917</a>
<a id='n918' href='#n918'>918</a>
<a id='n919' href='#n919'>919</a>
<a id='n920' href='#n920'>920</a>
<a id='n921' href='#n921'>921</a>
<a id='n922' href='#n922'>922</a>
<a id='n923' href='#n923'>923</a>
<a id='n924' href='#n924'>924</a>
<a id='n925' href='#n925'>925</a>
<a id='n926' href='#n926'>926</a>
<a id='n927' href='#n927'>927</a>
<a id='n928' href='#n928'>928</a>
<a id='n929' href='#n929'>929</a>
<a id='n930' href='#n930'>930</a>
<a id='n931' href='#n931'>931</a>
<a id='n932' href='#n932'>932</a>
<a id='n933' href='#n933'>933</a>
<a id='n934' href='#n934'>934</a>
<a id='n935' href='#n935'>935</a>
<a id='n936' href='#n936'>936</a>
<a id='n937' href='#n937'>937</a>
<a id='n938' href='#n938'>938</a>
<a id='n939' href='#n939'>939</a>
<a id='n940' href='#n940'>940</a>
<a id='n941' href='#n941'>941</a>
<a id='n942' href='#n942'>942</a>
<a id='n943' href='#n943'>943</a>
<a id='n944' href='#n944'>944</a>
<a id='n945' href='#n945'>945</a>
<a id='n946' href='#n946'>946</a>
<a id='n947' href='#n947'>947</a>
<a id='n948' href='#n948'>948</a>
<a id='n949' href='#n949'>949</a>
<a id='n950' href='#n950'>950</a>
<a id='n951' href='#n951'>951</a>
<a id='n952' href='#n952'>952</a>
<a id='n953' href='#n953'>953</a>
<a id='n954' href='#n954'>954</a>
<a id='n955' href='#n955'>955</a>
<a id='n956' href='#n956'>956</a>
<a id='n957' href='#n957'>957</a>
<a id='n958' href='#n958'>958</a>
<a id='n959' href='#n959'>959</a>
<a id='n960' href='#n960'>960</a>
<a id='n961' href='#n961'>961</a>
<a id='n962' href='#n962'>962</a>
<a id='n963' href='#n963'>963</a>
<a id='n964' href='#n964'>964</a>
<a id='n965' href='#n965'>965</a>
<a id='n966' href='#n966'>966</a>
<a id='n967' href='#n967'>967</a>
<a id='n968' href='#n968'>968</a>
<a id='n969' href='#n969'>969</a>
<a id='n970' href='#n970'>970</a>
<a id='n971' href='#n971'>971</a>
<a id='n972' href='#n972'>972</a>
<a id='n973' href='#n973'>973</a>
<a id='n974' href='#n974'>974</a>
<a id='n975' href='#n975'>975</a>
<a id='n976' href='#n976'>976</a>
<a id='n977' href='#n977'>977</a>
<a id='n978' href='#n978'>978</a>
<a id='n979' href='#n979'>979</a>
<a id='n980' href='#n980'>980</a>
<a id='n981' href='#n981'>981</a>
<a id='n982' href='#n982'>982</a>
<a id='n983' href='#n983'>983</a>
<a id='n984' href='#n984'>984</a>
<a id='n985' href='#n985'>985</a>
<a id='n986' href='#n986'>986</a>
<a id='n987' href='#n987'>987</a>
<a id='n988' href='#n988'>988</a>
<a id='n989' href='#n989'>989</a>
<a id='n990' href='#n990'>990</a>
<a id='n991' href='#n991'>991</a>
<a id='n992' href='#n992'>992</a>
<a id='n993' href='#n993'>993</a>
<a id='n994' href='#n994'>994</a>
<a id='n995' href='#n995'>995</a>
<a id='n996' href='#n996'>996</a>
<a id='n997' href='#n997'>997</a>
<a id='n998' href='#n998'>998</a>
<a id='n999' href='#n999'>999</a>
<a id='n1000' href='#n1000'>1000</a>
<a id='n1001' href='#n1001'>1001</a>
<a id='n1002' href='#n1002'>1002</a>
<a id='n1003' href='#n1003'>1003</a>
<a id='n1004' href='#n1004'>1004</a>
<a id='n1005' href='#n1005'>1005</a>
<a id='n1006' href='#n1006'>1006</a>
<a id='n1007' href='#n1007'>1007</a>
<a id='n1008' href='#n1008'>1008</a>
<a id='n1009' href='#n1009'>1009</a>
<a id='n1010' href='#n1010'>1010</a>
<a id='n1011' href='#n1011'>1011</a>
<a id='n1012' href='#n1012'>1012</a>
<a id='n1013' href='#n1013'>1013</a>
<a id='n1014' href='#n1014'>1014</a>
<a id='n1015' href='#n1015'>1015</a>
<a id='n1016' href='#n1016'>1016</a>
<a id='n1017' href='#n1017'>1017</a>
<a id='n1018' href='#n1018'>1018</a>
<a id='n1019' href='#n1019'>1019</a>
<a id='n1020' href='#n1020'>1020</a>
<a id='n1021' href='#n1021'>1021</a>
<a id='n1022' href='#n1022'>1022</a>
<a id='n1023' href='#n1023'>1023</a>
<a id='n1024' href='#n1024'>1024</a>
<a id='n1025' href='#n1025'>1025</a>
<a id='n1026' href='#n1026'>1026</a>
<a id='n1027' href='#n1027'>1027</a>
<a id='n1028' href='#n1028'>1028</a>
<a id='n1029' href='#n1029'>1029</a>
<a id='n1030' href='#n1030'>1030</a>
<a id='n1031' href='#n1031'>1031</a>
<a id='n1032' href='#n1032'>1032</a>
<a id='n1033' href='#n1033'>1033</a>
<a id='n1034' href='#n1034'>1034</a>
<a id='n1035' href='#n1035'>1035</a>
<a id='n1036' href='#n1036'>1036</a>
<a id='n1037' href='#n1037'>1037</a>
<a id='n1038' href='#n1038'>1038</a>
<a id='n1039' href='#n1039'>1039</a>
<a id='n1040' href='#n1040'>1040</a>
<a id='n1041' href='#n1041'>1041</a>
<a id='n1042' href='#n1042'>1042</a>
<a id='n1043' href='#n1043'>1043</a>
<a id='n1044' href='#n1044'>1044</a>
<a id='n1045' href='#n1045'>1045</a>
<a id='n1046' href='#n1046'>1046</a>
<a id='n1047' href='#n1047'>1047</a>
<a id='n1048' href='#n1048'>1048</a>
<a id='n1049' href='#n1049'>1049</a>
<a id='n1050' href='#n1050'>1050</a>
<a id='n1051' href='#n1051'>1051</a>
<a id='n1052' href='#n1052'>1052</a>
<a id='n1053' href='#n1053'>1053</a>
<a id='n1054' href='#n1054'>1054</a>
<a id='n1055' href='#n1055'>1055</a>
<a id='n1056' href='#n1056'>1056</a>
<a id='n1057' href='#n1057'>1057</a>
<a id='n1058' href='#n1058'>1058</a>
<a id='n1059' href='#n1059'>1059</a>
<a id='n1060' href='#n1060'>1060</a>
<a id='n1061' href='#n1061'>1061</a>
<a id='n1062' href='#n1062'>1062</a>
<a id='n1063' href='#n1063'>1063</a>
<a id='n1064' href='#n1064'>1064</a>
<a id='n1065' href='#n1065'>1065</a>
<a id='n1066' href='#n1066'>1066</a>
<a id='n1067' href='#n1067'>1067</a>
<a id='n1068' href='#n1068'>1068</a>
<a id='n1069' href='#n1069'>1069</a>
<a id='n1070' href='#n1070'>1070</a>
<a id='n1071' href='#n1071'>1071</a>
<a id='n1072' href='#n1072'>1072</a>
<a id='n1073' href='#n1073'>1073</a>
<a id='n1074' href='#n1074'>1074</a>
<a id='n1075' href='#n1075'>1075</a>
<a id='n1076' href='#n1076'>1076</a>
<a id='n1077' href='#n1077'>1077</a>
<a id='n1078' href='#n1078'>1078</a>
<a id='n1079' href='#n1079'>1079</a>
<a id='n1080' href='#n1080'>1080</a>
<a id='n1081' href='#n1081'>1081</a>
<a id='n1082' href='#n1082'>1082</a>
<a id='n1083' href='#n1083'>1083</a>
<a id='n1084' href='#n1084'>1084</a>
<a id='n1085' href='#n1085'>1085</a>
<a id='n1086' href='#n1086'>1086</a>
<a id='n1087' href='#n1087'>1087</a>
<a id='n1088' href='#n1088'>1088</a>
<a id='n1089' href='#n1089'>1089</a>
<a id='n1090' href='#n1090'>1090</a>
<a id='n1091' href='#n1091'>1091</a>
<a id='n1092' href='#n1092'>1092</a>
<a id='n1093' href='#n1093'>1093</a>
<a id='n1094' href='#n1094'>1094</a>
<a id='n1095' href='#n1095'>1095</a>
<a id='n1096' href='#n1096'>1096</a>
<a id='n1097' href='#n1097'>1097</a>
<a id='n1098' href='#n1098'>1098</a>
<a id='n1099' href='#n1099'>1099</a>
<a id='n1100' href='#n1100'>1100</a>
<a id='n1101' href='#n1101'>1101</a>
<a id='n1102' href='#n1102'>1102</a>
<a id='n1103' href='#n1103'>1103</a>
<a id='n1104' href='#n1104'>1104</a>
<a id='n1105' href='#n1105'>1105</a>
<a id='n1106' href='#n1106'>1106</a>
<a id='n1107' href='#n1107'>1107</a>
<a id='n1108' href='#n1108'>1108</a>
<a id='n1109' href='#n1109'>1109</a>
<a id='n1110' href='#n1110'>1110</a>
<a id='n1111' href='#n1111'>1111</a>
<a id='n1112' href='#n1112'>1112</a>
<a id='n1113' href='#n1113'>1113</a>
<a id='n1114' href='#n1114'>1114</a>
<a id='n1115' href='#n1115'>1115</a>
<a id='n1116' href='#n1116'>1116</a>
<a id='n1117' href='#n1117'>1117</a>
<a id='n1118' href='#n1118'>1118</a>
<a id='n1119' href='#n1119'>1119</a>
<a id='n1120' href='#n1120'>1120</a>
<a id='n1121' href='#n1121'>1121</a>
<a id='n1122' href='#n1122'>1122</a>
<a id='n1123' href='#n1123'>1123</a>
<a id='n1124' href='#n1124'>1124</a>
<a id='n1125' href='#n1125'>1125</a>
<a id='n1126' href='#n1126'>1126</a>
<a id='n1127' href='#n1127'>1127</a>
<a id='n1128' href='#n1128'>1128</a>
<a id='n1129' href='#n1129'>1129</a>
<a id='n1130' href='#n1130'>1130</a>
<a id='n1131' href='#n1131'>1131</a>
<a id='n1132' href='#n1132'>1132</a>
<a id='n1133' href='#n1133'>1133</a>
<a id='n1134' href='#n1134'>1134</a>
<a id='n1135' href='#n1135'>1135</a>
<a id='n1136' href='#n1136'>1136</a>
<a id='n1137' href='#n1137'>1137</a>
<a id='n1138' href='#n1138'>1138</a>
<a id='n1139' href='#n1139'>1139</a>
<a id='n1140' href='#n1140'>1140</a>
<a id='n1141' href='#n1141'>1141</a>
<a id='n1142' href='#n1142'>1142</a>
<a id='n1143' href='#n1143'>1143</a>
<a id='n1144' href='#n1144'>1144</a>
<a id='n1145' href='#n1145'>1145</a>
<a id='n1146' href='#n1146'>1146</a>
<a id='n1147' href='#n1147'>1147</a>
<a id='n1148' href='#n1148'>1148</a>
<a id='n1149' href='#n1149'>1149</a>
<a id='n1150' href='#n1150'>1150</a>
<a id='n1151' href='#n1151'>1151</a>
<a id='n1152' href='#n1152'>1152</a>
<a id='n1153' href='#n1153'>1153</a>
<a id='n1154' href='#n1154'>1154</a>
<a id='n1155' href='#n1155'>1155</a>
<a id='n1156' href='#n1156'>1156</a>
<a id='n1157' href='#n1157'>1157</a>
<a id='n1158' href='#n1158'>1158</a>
<a id='n1159' href='#n1159'>1159</a>
<a id='n1160' href='#n1160'>1160</a>
<a id='n1161' href='#n1161'>1161</a>
<a id='n1162' href='#n1162'>1162</a>
<a id='n1163' href='#n1163'>1163</a>
<a id='n1164' href='#n1164'>1164</a>
<a id='n1165' href='#n1165'>1165</a>
<a id='n1166' href='#n1166'>1166</a>
<a id='n1167' href='#n1167'>1167</a>
<a id='n1168' href='#n1168'>1168</a>
<a id='n1169' href='#n1169'>1169</a>
<a id='n1170' href='#n1170'>1170</a>
<a id='n1171' href='#n1171'>1171</a>
<a id='n1172' href='#n1172'>1172</a>
<a id='n1173' href='#n1173'>1173</a>
<a id='n1174' href='#n1174'>1174</a>
<a id='n1175' href='#n1175'>1175</a>
<a id='n1176' href='#n1176'>1176</a>
<a id='n1177' href='#n1177'>1177</a>
<a id='n1178' href='#n1178'>1178</a>
<a id='n1179' href='#n1179'>1179</a>
<a id='n1180' href='#n1180'>1180</a>
<a id='n1181' href='#n1181'>1181</a>
<a id='n1182' href='#n1182'>1182</a>
<a id='n1183' href='#n1183'>1183</a>
<a id='n1184' href='#n1184'>1184</a>
<a id='n1185' href='#n1185'>1185</a>
<a id='n1186' href='#n1186'>1186</a>
<a id='n1187' href='#n1187'>1187</a>
<a id='n1188' href='#n1188'>1188</a>
<a id='n1189' href='#n1189'>1189</a>
<a id='n1190' href='#n1190'>1190</a>
<a id='n1191' href='#n1191'>1191</a>
<a id='n1192' href='#n1192'>1192</a>
<a id='n1193' href='#n1193'>1193</a>
<a id='n1194' href='#n1194'>1194</a>
<a id='n1195' href='#n1195'>1195</a>
<a id='n1196' href='#n1196'>1196</a>
<a id='n1197' href='#n1197'>1197</a>
<a id='n1198' href='#n1198'>1198</a>
<a id='n1199' href='#n1199'>1199</a>
<a id='n1200' href='#n1200'>1200</a>
<a id='n1201' href='#n1201'>1201</a>
<a id='n1202' href='#n1202'>1202</a>
<a id='n1203' href='#n1203'>1203</a>
<a id='n1204' href='#n1204'>1204</a>
<a id='n1205' href='#n1205'>1205</a>
<a id='n1206' href='#n1206'>1206</a>
<a id='n1207' href='#n1207'>1207</a>
<a id='n1208' href='#n1208'>1208</a>
<a id='n1209' href='#n1209'>1209</a>
<a id='n1210' href='#n1210'>1210</a>
<a id='n1211' href='#n1211'>1211</a>
<a id='n1212' href='#n1212'>1212</a>
<a id='n1213' href='#n1213'>1213</a>
<a id='n1214' href='#n1214'>1214</a>
<a id='n1215' href='#n1215'>1215</a>
<a id='n1216' href='#n1216'>1216</a>
<a id='n1217' href='#n1217'>1217</a>
<a id='n1218' href='#n1218'>1218</a>
<a id='n1219' href='#n1219'>1219</a>
<a id='n1220' href='#n1220'>1220</a>
<a id='n1221' href='#n1221'>1221</a>
<a id='n1222' href='#n1222'>1222</a>
<a id='n1223' href='#n1223'>1223</a>
<a id='n1224' href='#n1224'>1224</a>
<a id='n1225' href='#n1225'>1225</a>
<a id='n1226' href='#n1226'>1226</a>
<a id='n1227' href='#n1227'>1227</a>
<a id='n1228' href='#n1228'>1228</a>
<a id='n1229' href='#n1229'>1229</a>
<a id='n1230' href='#n1230'>1230</a>
<a id='n1231' href='#n1231'>1231</a>
<a id='n1232' href='#n1232'>1232</a>
<a id='n1233' href='#n1233'>1233</a>
<a id='n1234' href='#n1234'>1234</a>
<a id='n1235' href='#n1235'>1235</a>
<a id='n1236' href='#n1236'>1236</a>
<a id='n1237' href='#n1237'>1237</a>
<a id='n1238' href='#n1238'>1238</a>
<a id='n1239' href='#n1239'>1239</a>
<a id='n1240' href='#n1240'>1240</a>
<a id='n1241' href='#n1241'>1241</a>
<a id='n1242' href='#n1242'>1242</a>
<a id='n1243' href='#n1243'>1243</a>
<a id='n1244' href='#n1244'>1244</a>
<a id='n1245' href='#n1245'>1245</a>
<a id='n1246' href='#n1246'>1246</a>
<a id='n1247' href='#n1247'>1247</a>
<a id='n1248' href='#n1248'>1248</a>
<a id='n1249' href='#n1249'>1249</a>
<a id='n1250' href='#n1250'>1250</a>
<a id='n1251' href='#n1251'>1251</a>
<a id='n1252' href='#n1252'>1252</a>
<a id='n1253' href='#n1253'>1253</a>
<a id='n1254' href='#n1254'>1254</a>
<a id='n1255' href='#n1255'>1255</a>
<a id='n1256' href='#n1256'>1256</a>
<a id='n1257' href='#n1257'>1257</a>
<a id='n1258' href='#n1258'>1258</a>
<a id='n1259' href='#n1259'>1259</a>
<a id='n1260' href='#n1260'>1260</a>
<a id='n1261' href='#n1261'>1261</a>
<a id='n1262' href='#n1262'>1262</a>
<a id='n1263' href='#n1263'>1263</a>
<a id='n1264' href='#n1264'>1264</a>
<a id='n1265' href='#n1265'>1265</a>
<a id='n1266' href='#n1266'>1266</a>
<a id='n1267' href='#n1267'>1267</a>
<a id='n1268' href='#n1268'>1268</a>
<a id='n1269' href='#n1269'>1269</a>
<a id='n1270' href='#n1270'>1270</a>
<a id='n1271' href='#n1271'>1271</a>
<a id='n1272' href='#n1272'>1272</a>
<a id='n1273' href='#n1273'>1273</a>
<a id='n1274' href='#n1274'>1274</a>
<a id='n1275' href='#n1275'>1275</a>
<a id='n1276' href='#n1276'>1276</a>
<a id='n1277' href='#n1277'>1277</a>
<a id='n1278' href='#n1278'>1278</a>
<a id='n1279' href='#n1279'>1279</a>
<a id='n1280' href='#n1280'>1280</a>
<a id='n1281' href='#n1281'>1281</a>
<a id='n1282' href='#n1282'>1282</a>
<a id='n1283' href='#n1283'>1283</a>
<a id='n1284' href='#n1284'>1284</a>
<a id='n1285' href='#n1285'>1285</a>
<a id='n1286' href='#n1286'>1286</a>
<a id='n1287' href='#n1287'>1287</a>
<a id='n1288' href='#n1288'>1288</a>
<a id='n1289' href='#n1289'>1289</a>
<a id='n1290' href='#n1290'>1290</a>
<a id='n1291' href='#n1291'>1291</a>
<a id='n1292' href='#n1292'>1292</a>
<a id='n1293' href='#n1293'>1293</a>
<a id='n1294' href='#n1294'>1294</a>
<a id='n1295' href='#n1295'>1295</a>
<a id='n1296' href='#n1296'>1296</a>
<a id='n1297' href='#n1297'>1297</a>
<a id='n1298' href='#n1298'>1298</a>
<a id='n1299' href='#n1299'>1299</a>
<a id='n1300' href='#n1300'>1300</a>
<a id='n1301' href='#n1301'>1301</a>
<a id='n1302' href='#n1302'>1302</a>
<a id='n1303' href='#n1303'>1303</a>
<a id='n1304' href='#n1304'>1304</a>
<a id='n1305' href='#n1305'>1305</a>
<a id='n1306' href='#n1306'>1306</a>
<a id='n1307' href='#n1307'>1307</a>
<a id='n1308' href='#n1308'>1308</a>
<a id='n1309' href='#n1309'>1309</a>
<a id='n1310' href='#n1310'>1310</a>
<a id='n1311' href='#n1311'>1311</a>
<a id='n1312' href='#n1312'>1312</a>
<a id='n1313' href='#n1313'>1313</a>
<a id='n1314' href='#n1314'>1314</a>
<a id='n1315' href='#n1315'>1315</a>
<a id='n1316' href='#n1316'>1316</a>
<a id='n1317' href='#n1317'>1317</a>
<a id='n1318' href='#n1318'>1318</a>
<a id='n1319' href='#n1319'>1319</a>
<a id='n1320' href='#n1320'>1320</a>
<a id='n1321' href='#n1321'>1321</a>
<a id='n1322' href='#n1322'>1322</a>
<a id='n1323' href='#n1323'>1323</a>
<a id='n1324' href='#n1324'>1324</a>
<a id='n1325' href='#n1325'>1325</a>
<a id='n1326' href='#n1326'>1326</a>
<a id='n1327' href='#n1327'>1327</a>
<a id='n1328' href='#n1328'>1328</a>
<a id='n1329' href='#n1329'>1329</a>
<a id='n1330' href='#n1330'>1330</a>
<a id='n1331' href='#n1331'>1331</a>
<a id='n1332' href='#n1332'>1332</a>
<a id='n1333' href='#n1333'>1333</a>
<a id='n1334' href='#n1334'>1334</a>
<a id='n1335' href='#n1335'>1335</a>
<a id='n1336' href='#n1336'>1336</a>
<a id='n1337' href='#n1337'>1337</a>
<a id='n1338' href='#n1338'>1338</a>
<a id='n1339' href='#n1339'>1339</a>
<a id='n1340' href='#n1340'>1340</a>
<a id='n1341' href='#n1341'>1341</a>
<a id='n1342' href='#n1342'>1342</a>
<a id='n1343' href='#n1343'>1343</a>
<a id='n1344' href='#n1344'>1344</a>
<a id='n1345' href='#n1345'>1345</a>
<a id='n1346' href='#n1346'>1346</a>
<a id='n1347' href='#n1347'>1347</a>
<a id='n1348' href='#n1348'>1348</a>
<a id='n1349' href='#n1349'>1349</a>
<a id='n1350' href='#n1350'>1350</a>
<a id='n1351' href='#n1351'>1351</a>
<a id='n1352' href='#n1352'>1352</a>
<a id='n1353' href='#n1353'>1353</a>
<a id='n1354' href='#n1354'>1354</a>
<a id='n1355' href='#n1355'>1355</a>
<a id='n1356' href='#n1356'>1356</a>
<a id='n1357' href='#n1357'>1357</a>
<a id='n1358' href='#n1358'>1358</a>
<a id='n1359' href='#n1359'>1359</a>
<a id='n1360' href='#n1360'>1360</a>
<a id='n1361' href='#n1361'>1361</a>
<a id='n1362' href='#n1362'>1362</a>
<a id='n1363' href='#n1363'>1363</a>
<a id='n1364' href='#n1364'>1364</a>
<a id='n1365' href='#n1365'>1365</a>
<a id='n1366' href='#n1366'>1366</a>
<a id='n1367' href='#n1367'>1367</a>
<a id='n1368' href='#n1368'>1368</a>
<a id='n1369' href='#n1369'>1369</a>
<a id='n1370' href='#n1370'>1370</a>
<a id='n1371' href='#n1371'>1371</a>
<a id='n1372' href='#n1372'>1372</a>
<a id='n1373' href='#n1373'>1373</a>
<a id='n1374' href='#n1374'>1374</a>
<a id='n1375' href='#n1375'>1375</a>
<a id='n1376' href='#n1376'>1376</a>
<a id='n1377' href='#n1377'>1377</a>
<a id='n1378' href='#n1378'>1378</a>
<a id='n1379' href='#n1379'>1379</a>
<a id='n1380' href='#n1380'>1380</a>
<a id='n1381' href='#n1381'>1381</a>
<a id='n1382' href='#n1382'>1382</a>
<a id='n1383' href='#n1383'>1383</a>
<a id='n1384' href='#n1384'>1384</a>
<a id='n1385' href='#n1385'>1385</a>
<a id='n1386' href='#n1386'>1386</a>
<a id='n1387' href='#n1387'>1387</a>
<a id='n1388' href='#n1388'>1388</a>
<a id='n1389' href='#n1389'>1389</a>
<a id='n1390' href='#n1390'>1390</a>
<a id='n1391' href='#n1391'>1391</a>
<a id='n1392' href='#n1392'>1392</a>
<a id='n1393' href='#n1393'>1393</a>
<a id='n1394' href='#n1394'>1394</a>
<a id='n1395' href='#n1395'>1395</a>
<a id='n1396' href='#n1396'>1396</a>
<a id='n1397' href='#n1397'>1397</a>
<a id='n1398' href='#n1398'>1398</a>
<a id='n1399' href='#n1399'>1399</a>
<a id='n1400' href='#n1400'>1400</a>
<a id='n1401' href='#n1401'>1401</a>
<a id='n1402' href='#n1402'>1402</a>
<a id='n1403' href='#n1403'>1403</a>
<a id='n1404' href='#n1404'>1404</a>
<a id='n1405' href='#n1405'>1405</a>
<a id='n1406' href='#n1406'>1406</a>
<a id='n1407' href='#n1407'>1407</a>
<a id='n1408' href='#n1408'>1408</a>
<a id='n1409' href='#n1409'>1409</a>
<a id='n1410' href='#n1410'>1410</a>
<a id='n1411' href='#n1411'>1411</a>
<a id='n1412' href='#n1412'>1412</a>
<a id='n1413' href='#n1413'>1413</a>
<a id='n1414' href='#n1414'>1414</a>
<a id='n1415' href='#n1415'>1415</a>
<a id='n1416' href='#n1416'>1416</a>
<a id='n1417' href='#n1417'>1417</a>
<a id='n1418' href='#n1418'>1418</a>
<a id='n1419' href='#n1419'>1419</a>
<a id='n1420' href='#n1420'>1420</a>
<a id='n1421' href='#n1421'>1421</a>
<a id='n1422' href='#n1422'>1422</a>
<a id='n1423' href='#n1423'>1423</a>
<a id='n1424' href='#n1424'>1424</a>
<a id='n1425' href='#n1425'>1425</a>
<a id='n1426' href='#n1426'>1426</a>
<a id='n1427' href='#n1427'>1427</a>
<a id='n1428' href='#n1428'>1428</a>
<a id='n1429' href='#n1429'>1429</a>
<a id='n1430' href='#n1430'>1430</a>
<a id='n1431' href='#n1431'>1431</a>
<a id='n1432' href='#n1432'>1432</a>
<a id='n1433' href='#n1433'>1433</a>
<a id='n1434' href='#n1434'>1434</a>
<a id='n1435' href='#n1435'>1435</a>
<a id='n1436' href='#n1436'>1436</a>
<a id='n1437' href='#n1437'>1437</a>
<a id='n1438' href='#n1438'>1438</a>
<a id='n1439' href='#n1439'>1439</a>
<a id='n1440' href='#n1440'>1440</a>
<a id='n1441' href='#n1441'>1441</a>
<a id='n1442' href='#n1442'>1442</a>
<a id='n1443' href='#n1443'>1443</a>
<a id='n1444' href='#n1444'>1444</a>
<a id='n1445' href='#n1445'>1445</a>
<a id='n1446' href='#n1446'>1446</a>
<a id='n1447' href='#n1447'>1447</a>
<a id='n1448' href='#n1448'>1448</a>
<a id='n1449' href='#n1449'>1449</a>
<a id='n1450' href='#n1450'>1450</a>
<a id='n1451' href='#n1451'>1451</a>
<a id='n1452' href='#n1452'>1452</a>
<a id='n1453' href='#n1453'>1453</a>
<a id='n1454' href='#n1454'>1454</a>
<a id='n1455' href='#n1455'>1455</a>
<a id='n1456' href='#n1456'>1456</a>
<a id='n1457' href='#n1457'>1457</a>
<a id='n1458' href='#n1458'>1458</a>
<a id='n1459' href='#n1459'>1459</a>
<a id='n1460' href='#n1460'>1460</a>
<a id='n1461' href='#n1461'>1461</a>
<a id='n1462' href='#n1462'>1462</a>
<a id='n1463' href='#n1463'>1463</a>
<a id='n1464' href='#n1464'>1464</a>
<a id='n1465' href='#n1465'>1465</a>
<a id='n1466' href='#n1466'>1466</a>
<a id='n1467' href='#n1467'>1467</a>
<a id='n1468' href='#n1468'>1468</a>
<a id='n1469' href='#n1469'>1469</a>
<a id='n1470' href='#n1470'>1470</a>
<a id='n1471' href='#n1471'>1471</a>
<a id='n1472' href='#n1472'>1472</a>
<a id='n1473' href='#n1473'>1473</a>
<a id='n1474' href='#n1474'>1474</a>
<a id='n1475' href='#n1475'>1475</a>
<a id='n1476' href='#n1476'>1476</a>
<a id='n1477' href='#n1477'>1477</a>
<a id='n1478' href='#n1478'>1478</a>
<a id='n1479' href='#n1479'>1479</a>
<a id='n1480' href='#n1480'>1480</a>
<a id='n1481' href='#n1481'>1481</a>
<a id='n1482' href='#n1482'>1482</a>
<a id='n1483' href='#n1483'>1483</a>
<a id='n1484' href='#n1484'>1484</a>
<a id='n1485' href='#n1485'>1485</a>
<a id='n1486' href='#n1486'>1486</a>
<a id='n1487' href='#n1487'>1487</a>
<a id='n1488' href='#n1488'>1488</a>
<a id='n1489' href='#n1489'>1489</a>
<a id='n1490' href='#n1490'>1490</a>
<a id='n1491' href='#n1491'>1491</a>
<a id='n1492' href='#n1492'>1492</a>
<a id='n1493' href='#n1493'>1493</a>
<a id='n1494' href='#n1494'>1494</a>
<a id='n1495' href='#n1495'>1495</a>
<a id='n1496' href='#n1496'>1496</a>
<a id='n1497' href='#n1497'>1497</a>
<a id='n1498' href='#n1498'>1498</a>
<a id='n1499' href='#n1499'>1499</a>
<a id='n1500' href='#n1500'>1500</a>
<a id='n1501' href='#n1501'>1501</a>
<a id='n1502' href='#n1502'>1502</a>
<a id='n1503' href='#n1503'>1503</a>
<a id='n1504' href='#n1504'>1504</a>
<a id='n1505' href='#n1505'>1505</a>
<a id='n1506' href='#n1506'>1506</a>
<a id='n1507' href='#n1507'>1507</a>
<a id='n1508' href='#n1508'>1508</a>
<a id='n1509' href='#n1509'>1509</a>
<a id='n1510' href='#n1510'>1510</a>
<a id='n1511' href='#n1511'>1511</a>
<a id='n1512' href='#n1512'>1512</a>
<a id='n1513' href='#n1513'>1513</a>
<a id='n1514' href='#n1514'>1514</a>
<a id='n1515' href='#n1515'>1515</a>
<a id='n1516' href='#n1516'>1516</a>
<a id='n1517' href='#n1517'>1517</a>
<a id='n1518' href='#n1518'>1518</a>
<a id='n1519' href='#n1519'>1519</a>
<a id='n1520' href='#n1520'>1520</a>
<a id='n1521' href='#n1521'>1521</a>
<a id='n1522' href='#n1522'>1522</a>
<a id='n1523' href='#n1523'>1523</a>
<a id='n1524' href='#n1524'>1524</a>
<a id='n1525' href='#n1525'>1525</a>
<a id='n1526' href='#n1526'>1526</a>
<a id='n1527' href='#n1527'>1527</a>
<a id='n1528' href='#n1528'>1528</a>
<a id='n1529' href='#n1529'>1529</a>
<a id='n1530' href='#n1530'>1530</a>
<a id='n1531' href='#n1531'>1531</a>
<a id='n1532' href='#n1532'>1532</a>
<a id='n1533' href='#n1533'>1533</a>
<a id='n1534' href='#n1534'>1534</a>
<a id='n1535' href='#n1535'>1535</a>
<a id='n1536' href='#n1536'>1536</a>
<a id='n1537' href='#n1537'>1537</a>
<a id='n1538' href='#n1538'>1538</a>
<a id='n1539' href='#n1539'>1539</a>
<a id='n1540' href='#n1540'>1540</a>
<a id='n1541' href='#n1541'>1541</a>
<a id='n1542' href='#n1542'>1542</a>
<a id='n1543' href='#n1543'>1543</a>
<a id='n1544' href='#n1544'>1544</a>
<a id='n1545' href='#n1545'>1545</a>
<a id='n1546' href='#n1546'>1546</a>
<a id='n1547' href='#n1547'>1547</a>
<a id='n1548' href='#n1548'>1548</a>
<a id='n1549' href='#n1549'>1549</a>
<a id='n1550' href='#n1550'>1550</a>
<a id='n1551' href='#n1551'>1551</a>
<a id='n1552' href='#n1552'>1552</a>
<a id='n1553' href='#n1553'>1553</a>
<a id='n1554' href='#n1554'>1554</a>
<a id='n1555' href='#n1555'>1555</a>
<a id='n1556' href='#n1556'>1556</a>
<a id='n1557' href='#n1557'>1557</a>
<a id='n1558' href='#n1558'>1558</a>
<a id='n1559' href='#n1559'>1559</a>
<a id='n1560' href='#n1560'>1560</a>
<a id='n1561' href='#n1561'>1561</a>
<a id='n1562' href='#n1562'>1562</a>
<a id='n1563' href='#n1563'>1563</a>
<a id='n1564' href='#n1564'>1564</a>
<a id='n1565' href='#n1565'>1565</a>
<a id='n1566' href='#n1566'>1566</a>
<a id='n1567' href='#n1567'>1567</a>
<a id='n1568' href='#n1568'>1568</a>
<a id='n1569' href='#n1569'>1569</a>
<a id='n1570' href='#n1570'>1570</a>
<a id='n1571' href='#n1571'>1571</a>
<a id='n1572' href='#n1572'>1572</a>
<a id='n1573' href='#n1573'>1573</a>
<a id='n1574' href='#n1574'>1574</a>
<a id='n1575' href='#n1575'>1575</a>
<a id='n1576' href='#n1576'>1576</a>
<a id='n1577' href='#n1577'>1577</a>
<a id='n1578' href='#n1578'>1578</a>
<a id='n1579' href='#n1579'>1579</a>
<a id='n1580' href='#n1580'>1580</a>
<a id='n1581' href='#n1581'>1581</a>
<a id='n1582' href='#n1582'>1582</a>
<a id='n1583' href='#n1583'>1583</a>
<a id='n1584' href='#n1584'>1584</a>
<a id='n1585' href='#n1585'>1585</a>
<a id='n1586' href='#n1586'>1586</a>
<a id='n1587' href='#n1587'>1587</a>
<a id='n1588' href='#n1588'>1588</a>
<a id='n1589' href='#n1589'>1589</a>
<a id='n1590' href='#n1590'>1590</a>
<a id='n1591' href='#n1591'>1591</a>
<a id='n1592' href='#n1592'>1592</a>
<a id='n1593' href='#n1593'>1593</a>
<a id='n1594' href='#n1594'>1594</a>
<a id='n1595' href='#n1595'>1595</a>
<a id='n1596' href='#n1596'>1596</a>
<a id='n1597' href='#n1597'>1597</a>
<a id='n1598' href='#n1598'>1598</a>
<a id='n1599' href='#n1599'>1599</a>
<a id='n1600' href='#n1600'>1600</a>
<a id='n1601' href='#n1601'>1601</a>
<a id='n1602' href='#n1602'>1602</a>
<a id='n1603' href='#n1603'>1603</a>
<a id='n1604' href='#n1604'>1604</a>
<a id='n1605' href='#n1605'>1605</a>
<a id='n1606' href='#n1606'>1606</a>
<a id='n1607' href='#n1607'>1607</a>
<a id='n1608' href='#n1608'>1608</a>
<a id='n1609' href='#n1609'>1609</a>
<a id='n1610' href='#n1610'>1610</a>
<a id='n1611' href='#n1611'>1611</a>
<a id='n1612' href='#n1612'>1612</a>
<a id='n1613' href='#n1613'>1613</a>
<a id='n1614' href='#n1614'>1614</a>
<a id='n1615' href='#n1615'>1615</a>
<a id='n1616' href='#n1616'>1616</a>
<a id='n1617' href='#n1617'>1617</a>
<a id='n1618' href='#n1618'>1618</a>
<a id='n1619' href='#n1619'>1619</a>
<a id='n1620' href='#n1620'>1620</a>
<a id='n1621' href='#n1621'>1621</a>
<a id='n1622' href='#n1622'>1622</a>
<a id='n1623' href='#n1623'>1623</a>
<a id='n1624' href='#n1624'>1624</a>
<a id='n1625' href='#n1625'>1625</a>
<a id='n1626' href='#n1626'>1626</a>
<a id='n1627' href='#n1627'>1627</a>
<a id='n1628' href='#n1628'>1628</a>
<a id='n1629' href='#n1629'>1629</a>
<a id='n1630' href='#n1630'>1630</a>
<a id='n1631' href='#n1631'>1631</a>
<a id='n1632' href='#n1632'>1632</a>
<a id='n1633' href='#n1633'>1633</a>
<a id='n1634' href='#n1634'>1634</a>
<a id='n1635' href='#n1635'>1635</a>
<a id='n1636' href='#n1636'>1636</a>
<a id='n1637' href='#n1637'>1637</a>
<a id='n1638' href='#n1638'>1638</a>
<a id='n1639' href='#n1639'>1639</a>
<a id='n1640' href='#n1640'>1640</a>
<a id='n1641' href='#n1641'>1641</a>
<a id='n1642' href='#n1642'>1642</a>
<a id='n1643' href='#n1643'>1643</a>
<a id='n1644' href='#n1644'>1644</a>
<a id='n1645' href='#n1645'>1645</a>
<a id='n1646' href='#n1646'>1646</a>
<a id='n1647' href='#n1647'>1647</a>
<a id='n1648' href='#n1648'>1648</a>
<a id='n1649' href='#n1649'>1649</a>
<a id='n1650' href='#n1650'>1650</a>
<a id='n1651' href='#n1651'>1651</a>
<a id='n1652' href='#n1652'>1652</a>
<a id='n1653' href='#n1653'>1653</a>
<a id='n1654' href='#n1654'>1654</a>
<a id='n1655' href='#n1655'>1655</a>
<a id='n1656' href='#n1656'>1656</a>
<a id='n1657' href='#n1657'>1657</a>
<a id='n1658' href='#n1658'>1658</a>
<a id='n1659' href='#n1659'>1659</a>
<a id='n1660' href='#n1660'>1660</a>
<a id='n1661' href='#n1661'>1661</a>
<a id='n1662' href='#n1662'>1662</a>
<a id='n1663' href='#n1663'>1663</a>
<a id='n1664' href='#n1664'>1664</a>
<a id='n1665' href='#n1665'>1665</a>
<a id='n1666' href='#n1666'>1666</a>
<a id='n1667' href='#n1667'>1667</a>
<a id='n1668' href='#n1668'>1668</a>
<a id='n1669' href='#n1669'>1669</a>
<a id='n1670' href='#n1670'>1670</a>
<a id='n1671' href='#n1671'>1671</a>
<a id='n1672' href='#n1672'>1672</a>
<a id='n1673' href='#n1673'>1673</a>
<a id='n1674' href='#n1674'>1674</a>
<a id='n1675' href='#n1675'>1675</a>
<a id='n1676' href='#n1676'>1676</a>
<a id='n1677' href='#n1677'>1677</a>
<a id='n1678' href='#n1678'>1678</a>
<a id='n1679' href='#n1679'>1679</a>
<a id='n1680' href='#n1680'>1680</a>
<a id='n1681' href='#n1681'>1681</a>
<a id='n1682' href='#n1682'>1682</a>
<a id='n1683' href='#n1683'>1683</a>
<a id='n1684' href='#n1684'>1684</a>
<a id='n1685' href='#n1685'>1685</a>
<a id='n1686' href='#n1686'>1686</a>
<a id='n1687' href='#n1687'>1687</a>
<a id='n1688' href='#n1688'>1688</a>
<a id='n1689' href='#n1689'>1689</a>
<a id='n1690' href='#n1690'>1690</a>
<a id='n1691' href='#n1691'>1691</a>
<a id='n1692' href='#n1692'>1692</a>
<a id='n1693' href='#n1693'>1693</a>
<a id='n1694' href='#n1694'>1694</a>
<a id='n1695' href='#n1695'>1695</a>
<a id='n1696' href='#n1696'>1696</a>
<a id='n1697' href='#n1697'>1697</a>
<a id='n1698' href='#n1698'>1698</a>
<a id='n1699' href='#n1699'>1699</a>
<a id='n1700' href='#n1700'>1700</a>
<a id='n1701' href='#n1701'>1701</a>
<a id='n1702' href='#n1702'>1702</a>
<a id='n1703' href='#n1703'>1703</a>
<a id='n1704' href='#n1704'>1704</a>
<a id='n1705' href='#n1705'>1705</a>
<a id='n1706' href='#n1706'>1706</a>
<a id='n1707' href='#n1707'>1707</a>
<a id='n1708' href='#n1708'>1708</a>
<a id='n1709' href='#n1709'>1709</a>
<a id='n1710' href='#n1710'>1710</a>
<a id='n1711' href='#n1711'>1711</a>
<a id='n1712' href='#n1712'>1712</a>
<a id='n1713' href='#n1713'>1713</a>
<a id='n1714' href='#n1714'>1714</a>
<a id='n1715' href='#n1715'>1715</a>
<a id='n1716' href='#n1716'>1716</a>
<a id='n1717' href='#n1717'>1717</a>
<a id='n1718' href='#n1718'>1718</a>
<a id='n1719' href='#n1719'>1719</a>
<a id='n1720' href='#n1720'>1720</a>
<a id='n1721' href='#n1721'>1721</a>
<a id='n1722' href='#n1722'>1722</a>
<a id='n1723' href='#n1723'>1723</a>
<a id='n1724' href='#n1724'>1724</a>
<a id='n1725' href='#n1725'>1725</a>
<a id='n1726' href='#n1726'>1726</a>
<a id='n1727' href='#n1727'>1727</a>
<a id='n1728' href='#n1728'>1728</a>
<a id='n1729' href='#n1729'>1729</a>
<a id='n1730' href='#n1730'>1730</a>
<a id='n1731' href='#n1731'>1731</a>
<a id='n1732' href='#n1732'>1732</a>
<a id='n1733' href='#n1733'>1733</a>
<a id='n1734' href='#n1734'>1734</a>
<a id='n1735' href='#n1735'>1735</a>
<a id='n1736' href='#n1736'>1736</a>
<a id='n1737' href='#n1737'>1737</a>
<a id='n1738' href='#n1738'>1738</a>
<a id='n1739' href='#n1739'>1739</a>
<a id='n1740' href='#n1740'>1740</a>
<a id='n1741' href='#n1741'>1741</a>
<a id='n1742' href='#n1742'>1742</a>
<a id='n1743' href='#n1743'>1743</a>
<a id='n1744' href='#n1744'>1744</a>
<a id='n1745' href='#n1745'>1745</a>
<a id='n1746' href='#n1746'>1746</a>
<a id='n1747' href='#n1747'>1747</a>
<a id='n1748' href='#n1748'>1748</a>
<a id='n1749' href='#n1749'>1749</a>
<a id='n1750' href='#n1750'>1750</a>
<a id='n1751' href='#n1751'>1751</a>
<a id='n1752' href='#n1752'>1752</a>
<a id='n1753' href='#n1753'>1753</a>
<a id='n1754' href='#n1754'>1754</a>
<a id='n1755' href='#n1755'>1755</a>
<a id='n1756' href='#n1756'>1756</a>
<a id='n1757' href='#n1757'>1757</a>
<a id='n1758' href='#n1758'>1758</a>
<a id='n1759' href='#n1759'>1759</a>
<a id='n1760' href='#n1760'>1760</a>
<a id='n1761' href='#n1761'>1761</a>
<a id='n1762' href='#n1762'>1762</a>
<a id='n1763' href='#n1763'>1763</a>
<a id='n1764' href='#n1764'>1764</a>
<a id='n1765' href='#n1765'>1765</a>
<a id='n1766' href='#n1766'>1766</a>
<a id='n1767' href='#n1767'>1767</a>
<a id='n1768' href='#n1768'>1768</a>
<a id='n1769' href='#n1769'>1769</a>
<a id='n1770' href='#n1770'>1770</a>
<a id='n1771' href='#n1771'>1771</a>
<a id='n1772' href='#n1772'>1772</a>
<a id='n1773' href='#n1773'>1773</a>
<a id='n1774' href='#n1774'>1774</a>
<a id='n1775' href='#n1775'>1775</a>
<a id='n1776' href='#n1776'>1776</a>
<a id='n1777' href='#n1777'>1777</a>
<a id='n1778' href='#n1778'>1778</a>
<a id='n1779' href='#n1779'>1779</a>
<a id='n1780' href='#n1780'>1780</a>
<a id='n1781' href='#n1781'>1781</a>
<a id='n1782' href='#n1782'>1782</a>
<a id='n1783' href='#n1783'>1783</a>
<a id='n1784' href='#n1784'>1784</a>
<a id='n1785' href='#n1785'>1785</a>
<a id='n1786' href='#n1786'>1786</a>
<a id='n1787' href='#n1787'>1787</a>
<a id='n1788' href='#n1788'>1788</a>
<a id='n1789' href='#n1789'>1789</a>
<a id='n1790' href='#n1790'>1790</a>
<a id='n1791' href='#n1791'>1791</a>
<a id='n1792' href='#n1792'>1792</a>
<a id='n1793' href='#n1793'>1793</a>
<a id='n1794' href='#n1794'>1794</a>
<a id='n1795' href='#n1795'>1795</a>
<a id='n1796' href='#n1796'>1796</a>
<a id='n1797' href='#n1797'>1797</a>
<a id='n1798' href='#n1798'>1798</a>
<a id='n1799' href='#n1799'>1799</a>
<a id='n1800' href='#n1800'>1800</a>
<a id='n1801' href='#n1801'>1801</a>
<a id='n1802' href='#n1802'>1802</a>
<a id='n1803' href='#n1803'>1803</a>
<a id='n1804' href='#n1804'>1804</a>
<a id='n1805' href='#n1805'>1805</a>
<a id='n1806' href='#n1806'>1806</a>
<a id='n1807' href='#n1807'>1807</a>
<a id='n1808' href='#n1808'>1808</a>
<a id='n1809' href='#n1809'>1809</a>
<a id='n1810' href='#n1810'>1810</a>
<a id='n1811' href='#n1811'>1811</a>
<a id='n1812' href='#n1812'>1812</a>
<a id='n1813' href='#n1813'>1813</a>
<a id='n1814' href='#n1814'>1814</a>
<a id='n1815' href='#n1815'>1815</a>
<a id='n1816' href='#n1816'>1816</a>
<a id='n1817' href='#n1817'>1817</a>
<a id='n1818' href='#n1818'>1818</a>
<a id='n1819' href='#n1819'>1819</a>
<a id='n1820' href='#n1820'>1820</a>
<a id='n1821' href='#n1821'>1821</a>
<a id='n1822' href='#n1822'>1822</a>
<a id='n1823' href='#n1823'>1823</a>
<a id='n1824' href='#n1824'>1824</a>
<a id='n1825' href='#n1825'>1825</a>
<a id='n1826' href='#n1826'>1826</a>
<a id='n1827' href='#n1827'>1827</a>
<a id='n1828' href='#n1828'>1828</a>
<a id='n1829' href='#n1829'>1829</a>
<a id='n1830' href='#n1830'>1830</a>
<a id='n1831' href='#n1831'>1831</a>
<a id='n1832' href='#n1832'>1832</a>
<a id='n1833' href='#n1833'>1833</a>
<a id='n1834' href='#n1834'>1834</a>
<a id='n1835' href='#n1835'>1835</a>
<a id='n1836' href='#n1836'>1836</a>
<a id='n1837' href='#n1837'>1837</a>
<a id='n1838' href='#n1838'>1838</a>
<a id='n1839' href='#n1839'>1839</a>
<a id='n1840' href='#n1840'>1840</a>
<a id='n1841' href='#n1841'>1841</a>
<a id='n1842' href='#n1842'>1842</a>
<a id='n1843' href='#n1843'>1843</a>
<a id='n1844' href='#n1844'>1844</a>
<a id='n1845' href='#n1845'>1845</a>
<a id='n1846' href='#n1846'>1846</a>
<a id='n1847' href='#n1847'>1847</a>
<a id='n1848' href='#n1848'>1848</a>
<a id='n1849' href='#n1849'>1849</a>
<a id='n1850' href='#n1850'>1850</a>
<a id='n1851' href='#n1851'>1851</a>
<a id='n1852' href='#n1852'>1852</a>
<a id='n1853' href='#n1853'>1853</a>
<a id='n1854' href='#n1854'>1854</a>
<a id='n1855' href='#n1855'>1855</a>
<a id='n1856' href='#n1856'>1856</a>
<a id='n1857' href='#n1857'>1857</a>
<a id='n1858' href='#n1858'>1858</a>
<a id='n1859' href='#n1859'>1859</a>
<a id='n1860' href='#n1860'>1860</a>
<a id='n1861' href='#n1861'>1861</a>
<a id='n1862' href='#n1862'>1862</a>
<a id='n1863' href='#n1863'>1863</a>
<a id='n1864' href='#n1864'>1864</a>
<a id='n1865' href='#n1865'>1865</a>
<a id='n1866' href='#n1866'>1866</a>
<a id='n1867' href='#n1867'>1867</a>
<a id='n1868' href='#n1868'>1868</a>
<a id='n1869' href='#n1869'>1869</a>
<a id='n1870' href='#n1870'>1870</a>
<a id='n1871' href='#n1871'>1871</a>
<a id='n1872' href='#n1872'>1872</a>
<a id='n1873' href='#n1873'>1873</a>
<a id='n1874' href='#n1874'>1874</a>
<a id='n1875' href='#n1875'>1875</a>
<a id='n1876' href='#n1876'>1876</a>
<a id='n1877' href='#n1877'>1877</a>
<a id='n1878' href='#n1878'>1878</a>
<a id='n1879' href='#n1879'>1879</a>
<a id='n1880' href='#n1880'>1880</a>
<a id='n1881' href='#n1881'>1881</a>
<a id='n1882' href='#n1882'>1882</a>
<a id='n1883' href='#n1883'>1883</a>
<a id='n1884' href='#n1884'>1884</a>
<a id='n1885' href='#n1885'>1885</a>
<a id='n1886' href='#n1886'>1886</a>
<a id='n1887' href='#n1887'>1887</a>
<a id='n1888' href='#n1888'>1888</a>
<a id='n1889' href='#n1889'>1889</a>
<a id='n1890' href='#n1890'>1890</a>
<a id='n1891' href='#n1891'>1891</a>
<a id='n1892' href='#n1892'>1892</a>
<a id='n1893' href='#n1893'>1893</a>
<a id='n1894' href='#n1894'>1894</a>
<a id='n1895' href='#n1895'>1895</a>
<a id='n1896' href='#n1896'>1896</a>
<a id='n1897' href='#n1897'>1897</a>
<a id='n1898' href='#n1898'>1898</a>
<a id='n1899' href='#n1899'>1899</a>
<a id='n1900' href='#n1900'>1900</a>
<a id='n1901' href='#n1901'>1901</a>
<a id='n1902' href='#n1902'>1902</a>
<a id='n1903' href='#n1903'>1903</a>
<a id='n1904' href='#n1904'>1904</a>
<a id='n1905' href='#n1905'>1905</a>
<a id='n1906' href='#n1906'>1906</a>
<a id='n1907' href='#n1907'>1907</a>
<a id='n1908' href='#n1908'>1908</a>
<a id='n1909' href='#n1909'>1909</a>
<a id='n1910' href='#n1910'>1910</a>
<a id='n1911' href='#n1911'>1911</a>
<a id='n1912' href='#n1912'>1912</a>
<a id='n1913' href='#n1913'>1913</a>
<a id='n1914' href='#n1914'>1914</a>
<a id='n1915' href='#n1915'>1915</a>
<a id='n1916' href='#n1916'>1916</a>
<a id='n1917' href='#n1917'>1917</a>
<a id='n1918' href='#n1918'>1918</a>
<a id='n1919' href='#n1919'>1919</a>
<a id='n1920' href='#n1920'>1920</a>
<a id='n1921' href='#n1921'>1921</a>
<a id='n1922' href='#n1922'>1922</a>
<a id='n1923' href='#n1923'>1923</a>
<a id='n1924' href='#n1924'>1924</a>
<a id='n1925' href='#n1925'>1925</a>
<a id='n1926' href='#n1926'>1926</a>
<a id='n1927' href='#n1927'>1927</a>
<a id='n1928' href='#n1928'>1928</a>
<a id='n1929' href='#n1929'>1929</a>
<a id='n1930' href='#n1930'>1930</a>
<a id='n1931' href='#n1931'>1931</a>
<a id='n1932' href='#n1932'>1932</a>
<a id='n1933' href='#n1933'>1933</a>
<a id='n1934' href='#n1934'>1934</a>
<a id='n1935' href='#n1935'>1935</a>
<a id='n1936' href='#n1936'>1936</a>
<a id='n1937' href='#n1937'>1937</a>
<a id='n1938' href='#n1938'>1938</a>
<a id='n1939' href='#n1939'>1939</a>
<a id='n1940' href='#n1940'>1940</a>
<a id='n1941' href='#n1941'>1941</a>
<a id='n1942' href='#n1942'>1942</a>
<a id='n1943' href='#n1943'>1943</a>
<a id='n1944' href='#n1944'>1944</a>
<a id='n1945' href='#n1945'>1945</a>
<a id='n1946' href='#n1946'>1946</a>
<a id='n1947' href='#n1947'>1947</a>
<a id='n1948' href='#n1948'>1948</a>
<a id='n1949' href='#n1949'>1949</a>
<a id='n1950' href='#n1950'>1950</a>
<a id='n1951' href='#n1951'>1951</a>
<a id='n1952' href='#n1952'>1952</a>
<a id='n1953' href='#n1953'>1953</a>
<a id='n1954' href='#n1954'>1954</a>
<a id='n1955' href='#n1955'>1955</a>
<a id='n1956' href='#n1956'>1956</a>
<a id='n1957' href='#n1957'>1957</a>
<a id='n1958' href='#n1958'>1958</a>
<a id='n1959' href='#n1959'>1959</a>
<a id='n1960' href='#n1960'>1960</a>
<a id='n1961' href='#n1961'>1961</a>
<a id='n1962' href='#n1962'>1962</a>
<a id='n1963' href='#n1963'>1963</a>
<a id='n1964' href='#n1964'>1964</a>
<a id='n1965' href='#n1965'>1965</a>
<a id='n1966' href='#n1966'>1966</a>
<a id='n1967' href='#n1967'>1967</a>
<a id='n1968' href='#n1968'>1968</a>
<a id='n1969' href='#n1969'>1969</a>
<a id='n1970' href='#n1970'>1970</a>
<a id='n1971' href='#n1971'>1971</a>
<a id='n1972' href='#n1972'>1972</a>
<a id='n1973' href='#n1973'>1973</a>
<a id='n1974' href='#n1974'>1974</a>
<a id='n1975' href='#n1975'>1975</a>
<a id='n1976' href='#n1976'>1976</a>
<a id='n1977' href='#n1977'>1977</a>
<a id='n1978' href='#n1978'>1978</a>
<a id='n1979' href='#n1979'>1979</a>
<a id='n1980' href='#n1980'>1980</a>
<a id='n1981' href='#n1981'>1981</a>
<a id='n1982' href='#n1982'>1982</a>
<a id='n1983' href='#n1983'>1983</a>
<a id='n1984' href='#n1984'>1984</a>
<a id='n1985' href='#n1985'>1985</a>
<a id='n1986' href='#n1986'>1986</a>
<a id='n1987' href='#n1987'>1987</a>
<a id='n1988' href='#n1988'>1988</a>
<a id='n1989' href='#n1989'>1989</a>
<a id='n1990' href='#n1990'>1990</a>
<a id='n1991' href='#n1991'>1991</a>
<a id='n1992' href='#n1992'>1992</a>
<a id='n1993' href='#n1993'>1993</a>
<a id='n1994' href='#n1994'>1994</a>
<a id='n1995' href='#n1995'>1995</a>
<a id='n1996' href='#n1996'>1996</a>
<a id='n1997' href='#n1997'>1997</a>
<a id='n1998' href='#n1998'>1998</a>
<a id='n1999' href='#n1999'>1999</a>
<a id='n2000' href='#n2000'>2000</a>
<a id='n2001' href='#n2001'>2001</a>
<a id='n2002' href='#n2002'>2002</a>
<a id='n2003' href='#n2003'>2003</a>
<a id='n2004' href='#n2004'>2004</a>
<a id='n2005' href='#n2005'>2005</a>
<a id='n2006' href='#n2006'>2006</a>
<a id='n2007' href='#n2007'>2007</a>
<a id='n2008' href='#n2008'>2008</a>
<a id='n2009' href='#n2009'>2009</a>
<a id='n2010' href='#n2010'>2010</a>
<a id='n2011' href='#n2011'>2011</a>
<a id='n2012' href='#n2012'>2012</a>
<a id='n2013' href='#n2013'>2013</a>
<a id='n2014' href='#n2014'>2014</a>
<a id='n2015' href='#n2015'>2015</a>
<a id='n2016' href='#n2016'>2016</a>
<a id='n2017' href='#n2017'>2017</a>
<a id='n2018' href='#n2018'>2018</a>
<a id='n2019' href='#n2019'>2019</a>
<a id='n2020' href='#n2020'>2020</a>
<a id='n2021' href='#n2021'>2021</a>
<a id='n2022' href='#n2022'>2022</a>
<a id='n2023' href='#n2023'>2023</a>
<a id='n2024' href='#n2024'>2024</a>
<a id='n2025' href='#n2025'>2025</a>
<a id='n2026' href='#n2026'>2026</a>
<a id='n2027' href='#n2027'>2027</a>
<a id='n2028' href='#n2028'>2028</a>
<a id='n2029' href='#n2029'>2029</a>
<a id='n2030' href='#n2030'>2030</a>
<a id='n2031' href='#n2031'>2031</a>
<a id='n2032' href='#n2032'>2032</a>
<a id='n2033' href='#n2033'>2033</a>
<a id='n2034' href='#n2034'>2034</a>
<a id='n2035' href='#n2035'>2035</a>
<a id='n2036' href='#n2036'>2036</a>
<a id='n2037' href='#n2037'>2037</a>
<a id='n2038' href='#n2038'>2038</a>
<a id='n2039' href='#n2039'>2039</a>
<a id='n2040' href='#n2040'>2040</a>
<a id='n2041' href='#n2041'>2041</a>
<a id='n2042' href='#n2042'>2042</a>
<a id='n2043' href='#n2043'>2043</a>
<a id='n2044' href='#n2044'>2044</a>
<a id='n2045' href='#n2045'>2045</a>
<a id='n2046' href='#n2046'>2046</a>
<a id='n2047' href='#n2047'>2047</a>
<a id='n2048' href='#n2048'>2048</a>
<a id='n2049' href='#n2049'>2049</a>
<a id='n2050' href='#n2050'>2050</a>
<a id='n2051' href='#n2051'>2051</a>
<a id='n2052' href='#n2052'>2052</a>
<a id='n2053' href='#n2053'>2053</a>
<a id='n2054' href='#n2054'>2054</a>
<a id='n2055' href='#n2055'>2055</a>
<a id='n2056' href='#n2056'>2056</a>
<a id='n2057' href='#n2057'>2057</a>
<a id='n2058' href='#n2058'>2058</a>
<a id='n2059' href='#n2059'>2059</a>
<a id='n2060' href='#n2060'>2060</a>
<a id='n2061' href='#n2061'>2061</a>
<a id='n2062' href='#n2062'>2062</a>
<a id='n2063' href='#n2063'>2063</a>
<a id='n2064' href='#n2064'>2064</a>
<a id='n2065' href='#n2065'>2065</a>
<a id='n2066' href='#n2066'>2066</a>
<a id='n2067' href='#n2067'>2067</a>
<a id='n2068' href='#n2068'>2068</a>
<a id='n2069' href='#n2069'>2069</a>
<a id='n2070' href='#n2070'>2070</a>
<a id='n2071' href='#n2071'>2071</a>
<a id='n2072' href='#n2072'>2072</a>
<a id='n2073' href='#n2073'>2073</a>
<a id='n2074' href='#n2074'>2074</a>
<a id='n2075' href='#n2075'>2075</a>
<a id='n2076' href='#n2076'>2076</a>
<a id='n2077' href='#n2077'>2077</a>
<a id='n2078' href='#n2078'>2078</a>
<a id='n2079' href='#n2079'>2079</a>
<a id='n2080' href='#n2080'>2080</a>
<a id='n2081' href='#n2081'>2081</a>
<a id='n2082' href='#n2082'>2082</a>
<a id='n2083' href='#n2083'>2083</a>
<a id='n2084' href='#n2084'>2084</a>
<a id='n2085' href='#n2085'>2085</a>
<a id='n2086' href='#n2086'>2086</a>
<a id='n2087' href='#n2087'>2087</a>
<a id='n2088' href='#n2088'>2088</a>
<a id='n2089' href='#n2089'>2089</a>
<a id='n2090' href='#n2090'>2090</a>
<a id='n2091' href='#n2091'>2091</a>
<a id='n2092' href='#n2092'>2092</a>
<a id='n2093' href='#n2093'>2093</a>
<a id='n2094' href='#n2094'>2094</a>
<a id='n2095' href='#n2095'>2095</a>
<a id='n2096' href='#n2096'>2096</a>
<a id='n2097' href='#n2097'>2097</a>
<a id='n2098' href='#n2098'>2098</a>
<a id='n2099' href='#n2099'>2099</a>
<a id='n2100' href='#n2100'>2100</a>
<a id='n2101' href='#n2101'>2101</a>
<a id='n2102' href='#n2102'>2102</a>
<a id='n2103' href='#n2103'>2103</a>
<a id='n2104' href='#n2104'>2104</a>
<a id='n2105' href='#n2105'>2105</a>
<a id='n2106' href='#n2106'>2106</a>
<a id='n2107' href='#n2107'>2107</a>
<a id='n2108' href='#n2108'>2108</a>
<a id='n2109' href='#n2109'>2109</a>
<a id='n2110' href='#n2110'>2110</a>
<a id='n2111' href='#n2111'>2111</a>
<a id='n2112' href='#n2112'>2112</a>
<a id='n2113' href='#n2113'>2113</a>
<a id='n2114' href='#n2114'>2114</a>
<a id='n2115' href='#n2115'>2115</a>
<a id='n2116' href='#n2116'>2116</a>
<a id='n2117' href='#n2117'>2117</a>
<a id='n2118' href='#n2118'>2118</a>
<a id='n2119' href='#n2119'>2119</a>
<a id='n2120' href='#n2120'>2120</a>
<a id='n2121' href='#n2121'>2121</a>
<a id='n2122' href='#n2122'>2122</a>
<a id='n2123' href='#n2123'>2123</a>
<a id='n2124' href='#n2124'>2124</a>
<a id='n2125' href='#n2125'>2125</a>
<a id='n2126' href='#n2126'>2126</a>
<a id='n2127' href='#n2127'>2127</a>
<a id='n2128' href='#n2128'>2128</a>
<a id='n2129' href='#n2129'>2129</a>
<a id='n2130' href='#n2130'>2130</a>
<a id='n2131' href='#n2131'>2131</a>
<a id='n2132' href='#n2132'>2132</a>
<a id='n2133' href='#n2133'>2133</a>
<a id='n2134' href='#n2134'>2134</a>
<a id='n2135' href='#n2135'>2135</a>
<a id='n2136' href='#n2136'>2136</a>
<a id='n2137' href='#n2137'>2137</a>
<a id='n2138' href='#n2138'>2138</a>
<a id='n2139' href='#n2139'>2139</a>
<a id='n2140' href='#n2140'>2140</a>
<a id='n2141' href='#n2141'>2141</a>
<a id='n2142' href='#n2142'>2142</a>
<a id='n2143' href='#n2143'>2143</a>
<a id='n2144' href='#n2144'>2144</a>
<a id='n2145' href='#n2145'>2145</a>
<a id='n2146' href='#n2146'>2146</a>
<a id='n2147' href='#n2147'>2147</a>
<a id='n2148' href='#n2148'>2148</a>
<a id='n2149' href='#n2149'>2149</a>
<a id='n2150' href='#n2150'>2150</a>
<a id='n2151' href='#n2151'>2151</a>
<a id='n2152' href='#n2152'>2152</a>
<a id='n2153' href='#n2153'>2153</a>
<a id='n2154' href='#n2154'>2154</a>
<a id='n2155' href='#n2155'>2155</a>
<a id='n2156' href='#n2156'>2156</a>
<a id='n2157' href='#n2157'>2157</a>
<a id='n2158' href='#n2158'>2158</a>
<a id='n2159' href='#n2159'>2159</a>
<a id='n2160' href='#n2160'>2160</a>
<a id='n2161' href='#n2161'>2161</a>
<a id='n2162' href='#n2162'>2162</a>
<a id='n2163' href='#n2163'>2163</a>
<a id='n2164' href='#n2164'>2164</a>
<a id='n2165' href='#n2165'>2165</a>
<a id='n2166' href='#n2166'>2166</a>
<a id='n2167' href='#n2167'>2167</a>
<a id='n2168' href='#n2168'>2168</a>
<a id='n2169' href='#n2169'>2169</a>
<a id='n2170' href='#n2170'>2170</a>
<a id='n2171' href='#n2171'>2171</a>
<a id='n2172' href='#n2172'>2172</a>
<a id='n2173' href='#n2173'>2173</a>
<a id='n2174' href='#n2174'>2174</a>
<a id='n2175' href='#n2175'>2175</a>
<a id='n2176' href='#n2176'>2176</a>
<a id='n2177' href='#n2177'>2177</a>
<a id='n2178' href='#n2178'>2178</a>
<a id='n2179' href='#n2179'>2179</a>
<a id='n2180' href='#n2180'>2180</a>
<a id='n2181' href='#n2181'>2181</a>
<a id='n2182' href='#n2182'>2182</a>
<a id='n2183' href='#n2183'>2183</a>
<a id='n2184' href='#n2184'>2184</a>
<a id='n2185' href='#n2185'>2185</a>
<a id='n2186' href='#n2186'>2186</a>
<a id='n2187' href='#n2187'>2187</a>
<a id='n2188' href='#n2188'>2188</a>
<a id='n2189' href='#n2189'>2189</a>
<a id='n2190' href='#n2190'>2190</a>
<a id='n2191' href='#n2191'>2191</a>
<a id='n2192' href='#n2192'>2192</a>
<a id='n2193' href='#n2193'>2193</a>
<a id='n2194' href='#n2194'>2194</a>
<a id='n2195' href='#n2195'>2195</a>
<a id='n2196' href='#n2196'>2196</a>
<a id='n2197' href='#n2197'>2197</a>
<a id='n2198' href='#n2198'>2198</a>
<a id='n2199' href='#n2199'>2199</a>
<a id='n2200' href='#n2200'>2200</a>
<a id='n2201' href='#n2201'>2201</a>
<a id='n2202' href='#n2202'>2202</a>
<a id='n2203' href='#n2203'>2203</a>
<a id='n2204' href='#n2204'>2204</a>
<a id='n2205' href='#n2205'>2205</a>
<a id='n2206' href='#n2206'>2206</a>
<a id='n2207' href='#n2207'>2207</a>
<a id='n2208' href='#n2208'>2208</a>
<a id='n2209' href='#n2209'>2209</a>
<a id='n2210' href='#n2210'>2210</a>
<a id='n2211' href='#n2211'>2211</a>
<a id='n2212' href='#n2212'>2212</a>
<a id='n2213' href='#n2213'>2213</a>
<a id='n2214' href='#n2214'>2214</a>
<a id='n2215' href='#n2215'>2215</a>
<a id='n2216' href='#n2216'>2216</a>
<a id='n2217' href='#n2217'>2217</a>
<a id='n2218' href='#n2218'>2218</a>
<a id='n2219' href='#n2219'>2219</a>
<a id='n2220' href='#n2220'>2220</a>
<a id='n2221' href='#n2221'>2221</a>
<a id='n2222' href='#n2222'>2222</a>
<a id='n2223' href='#n2223'>2223</a>
<a id='n2224' href='#n2224'>2224</a>
<a id='n2225' href='#n2225'>2225</a>
<a id='n2226' href='#n2226'>2226</a>
<a id='n2227' href='#n2227'>2227</a>
<a id='n2228' href='#n2228'>2228</a>
<a id='n2229' href='#n2229'>2229</a>
<a id='n2230' href='#n2230'>2230</a>
<a id='n2231' href='#n2231'>2231</a>
<a id='n2232' href='#n2232'>2232</a>
<a id='n2233' href='#n2233'>2233</a>
<a id='n2234' href='#n2234'>2234</a>
<a id='n2235' href='#n2235'>2235</a>
<a id='n2236' href='#n2236'>2236</a>
<a id='n2237' href='#n2237'>2237</a>
<a id='n2238' href='#n2238'>2238</a>
<a id='n2239' href='#n2239'>2239</a>
<a id='n2240' href='#n2240'>2240</a>
<a id='n2241' href='#n2241'>2241</a>
<a id='n2242' href='#n2242'>2242</a>
<a id='n2243' href='#n2243'>2243</a>
<a id='n2244' href='#n2244'>2244</a>
<a id='n2245' href='#n2245'>2245</a>
<a id='n2246' href='#n2246'>2246</a>
<a id='n2247' href='#n2247'>2247</a>
<a id='n2248' href='#n2248'>2248</a>
<a id='n2249' href='#n2249'>2249</a>
<a id='n2250' href='#n2250'>2250</a>
<a id='n2251' href='#n2251'>2251</a>
<a id='n2252' href='#n2252'>2252</a>
<a id='n2253' href='#n2253'>2253</a>
<a id='n2254' href='#n2254'>2254</a>
<a id='n2255' href='#n2255'>2255</a>
<a id='n2256' href='#n2256'>2256</a>
<a id='n2257' href='#n2257'>2257</a>
<a id='n2258' href='#n2258'>2258</a>
<a id='n2259' href='#n2259'>2259</a>
<a id='n2260' href='#n2260'>2260</a>
<a id='n2261' href='#n2261'>2261</a>
<a id='n2262' href='#n2262'>2262</a>
<a id='n2263' href='#n2263'>2263</a>
<a id='n2264' href='#n2264'>2264</a>
<a id='n2265' href='#n2265'>2265</a>
<a id='n2266' href='#n2266'>2266</a>
<a id='n2267' href='#n2267'>2267</a>
<a id='n2268' href='#n2268'>2268</a>
<a id='n2269' href='#n2269'>2269</a>
<a id='n2270' href='#n2270'>2270</a>
<a id='n2271' href='#n2271'>2271</a>
<a id='n2272' href='#n2272'>2272</a>
<a id='n2273' href='#n2273'>2273</a>
<a id='n2274' href='#n2274'>2274</a>
<a id='n2275' href='#n2275'>2275</a>
<a id='n2276' href='#n2276'>2276</a>
<a id='n2277' href='#n2277'>2277</a>
<a id='n2278' href='#n2278'>2278</a>
<a id='n2279' href='#n2279'>2279</a>
<a id='n2280' href='#n2280'>2280</a>
<a id='n2281' href='#n2281'>2281</a>
<a id='n2282' href='#n2282'>2282</a>
<a id='n2283' href='#n2283'>2283</a>
<a id='n2284' href='#n2284'>2284</a>
<a id='n2285' href='#n2285'>2285</a>
<a id='n2286' href='#n2286'>2286</a>
<a id='n2287' href='#n2287'>2287</a>
<a id='n2288' href='#n2288'>2288</a>
<a id='n2289' href='#n2289'>2289</a>
<a id='n2290' href='#n2290'>2290</a>
<a id='n2291' href='#n2291'>2291</a>
<a id='n2292' href='#n2292'>2292</a>
<a id='n2293' href='#n2293'>2293</a>
<a id='n2294' href='#n2294'>2294</a>
<a id='n2295' href='#n2295'>2295</a>
<a id='n2296' href='#n2296'>2296</a>
<a id='n2297' href='#n2297'>2297</a>
<a id='n2298' href='#n2298'>2298</a>
<a id='n2299' href='#n2299'>2299</a>
<a id='n2300' href='#n2300'>2300</a>
<a id='n2301' href='#n2301'>2301</a>
<a id='n2302' href='#n2302'>2302</a>
<a id='n2303' href='#n2303'>2303</a>
<a id='n2304' href='#n2304'>2304</a>
<a id='n2305' href='#n2305'>2305</a>
<a id='n2306' href='#n2306'>2306</a>
<a id='n2307' href='#n2307'>2307</a>
<a id='n2308' href='#n2308'>2308</a>
<a id='n2309' href='#n2309'>2309</a>
<a id='n2310' href='#n2310'>2310</a>
<a id='n2311' href='#n2311'>2311</a>
<a id='n2312' href='#n2312'>2312</a>
<a id='n2313' href='#n2313'>2313</a>
<a id='n2314' href='#n2314'>2314</a>
<a id='n2315' href='#n2315'>2315</a>
<a id='n2316' href='#n2316'>2316</a>
<a id='n2317' href='#n2317'>2317</a>
<a id='n2318' href='#n2318'>2318</a>
<a id='n2319' href='#n2319'>2319</a>
<a id='n2320' href='#n2320'>2320</a>
<a id='n2321' href='#n2321'>2321</a>
<a id='n2322' href='#n2322'>2322</a>
<a id='n2323' href='#n2323'>2323</a>
<a id='n2324' href='#n2324'>2324</a>
<a id='n2325' href='#n2325'>2325</a>
<a id='n2326' href='#n2326'>2326</a>
<a id='n2327' href='#n2327'>2327</a>
<a id='n2328' href='#n2328'>2328</a>
<a id='n2329' href='#n2329'>2329</a>
<a id='n2330' href='#n2330'>2330</a>
<a id='n2331' href='#n2331'>2331</a>
<a id='n2332' href='#n2332'>2332</a>
<a id='n2333' href='#n2333'>2333</a>
<a id='n2334' href='#n2334'>2334</a>
<a id='n2335' href='#n2335'>2335</a>
<a id='n2336' href='#n2336'>2336</a>
<a id='n2337' href='#n2337'>2337</a>
<a id='n2338' href='#n2338'>2338</a>
<a id='n2339' href='#n2339'>2339</a>
<a id='n2340' href='#n2340'>2340</a>
<a id='n2341' href='#n2341'>2341</a>
<a id='n2342' href='#n2342'>2342</a>
<a id='n2343' href='#n2343'>2343</a>
<a id='n2344' href='#n2344'>2344</a>
<a id='n2345' href='#n2345'>2345</a>
<a id='n2346' href='#n2346'>2346</a>
<a id='n2347' href='#n2347'>2347</a>
<a id='n2348' href='#n2348'>2348</a>
<a id='n2349' href='#n2349'>2349</a>
<a id='n2350' href='#n2350'>2350</a>
<a id='n2351' href='#n2351'>2351</a>
<a id='n2352' href='#n2352'>2352</a>
<a id='n2353' href='#n2353'>2353</a>
<a id='n2354' href='#n2354'>2354</a>
<a id='n2355' href='#n2355'>2355</a>
<a id='n2356' href='#n2356'>2356</a>
<a id='n2357' href='#n2357'>2357</a>
<a id='n2358' href='#n2358'>2358</a>
<a id='n2359' href='#n2359'>2359</a>
<a id='n2360' href='#n2360'>2360</a>
<a id='n2361' href='#n2361'>2361</a>
<a id='n2362' href='#n2362'>2362</a>
<a id='n2363' href='#n2363'>2363</a>
<a id='n2364' href='#n2364'>2364</a>
<a id='n2365' href='#n2365'>2365</a>
<a id='n2366' href='#n2366'>2366</a>
<a id='n2367' href='#n2367'>2367</a>
<a id='n2368' href='#n2368'>2368</a>
<a id='n2369' href='#n2369'>2369</a>
<a id='n2370' href='#n2370'>2370</a>
<a id='n2371' href='#n2371'>2371</a>
<a id='n2372' href='#n2372'>2372</a>
<a id='n2373' href='#n2373'>2373</a>
<a id='n2374' href='#n2374'>2374</a>
<a id='n2375' href='#n2375'>2375</a>
<a id='n2376' href='#n2376'>2376</a>
<a id='n2377' href='#n2377'>2377</a>
<a id='n2378' href='#n2378'>2378</a>
<a id='n2379' href='#n2379'>2379</a>
<a id='n2380' href='#n2380'>2380</a>
<a id='n2381' href='#n2381'>2381</a>
<a id='n2382' href='#n2382'>2382</a>
<a id='n2383' href='#n2383'>2383</a>
<a id='n2384' href='#n2384'>2384</a>
<a id='n2385' href='#n2385'>2385</a>
<a id='n2386' href='#n2386'>2386</a>
<a id='n2387' href='#n2387'>2387</a>
<a id='n2388' href='#n2388'>2388</a>
<a id='n2389' href='#n2389'>2389</a>
<a id='n2390' href='#n2390'>2390</a>
<a id='n2391' href='#n2391'>2391</a>
<a id='n2392' href='#n2392'>2392</a>
<a id='n2393' href='#n2393'>2393</a>
<a id='n2394' href='#n2394'>2394</a>
<a id='n2395' href='#n2395'>2395</a>
<a id='n2396' href='#n2396'>2396</a>
<a id='n2397' href='#n2397'>2397</a>
<a id='n2398' href='#n2398'>2398</a>
<a id='n2399' href='#n2399'>2399</a>
<a id='n2400' href='#n2400'>2400</a>
<a id='n2401' href='#n2401'>2401</a>
<a id='n2402' href='#n2402'>2402</a>
<a id='n2403' href='#n2403'>2403</a>
<a id='n2404' href='#n2404'>2404</a>
<a id='n2405' href='#n2405'>2405</a>
<a id='n2406' href='#n2406'>2406</a>
<a id='n2407' href='#n2407'>2407</a>
<a id='n2408' href='#n2408'>2408</a>
<a id='n2409' href='#n2409'>2409</a>
<a id='n2410' href='#n2410'>2410</a>
<a id='n2411' href='#n2411'>2411</a>
<a id='n2412' href='#n2412'>2412</a>
<a id='n2413' href='#n2413'>2413</a>
<a id='n2414' href='#n2414'>2414</a>
<a id='n2415' href='#n2415'>2415</a>
<a id='n2416' href='#n2416'>2416</a>
<a id='n2417' href='#n2417'>2417</a>
<a id='n2418' href='#n2418'>2418</a>
<a id='n2419' href='#n2419'>2419</a>
<a id='n2420' href='#n2420'>2420</a>
<a id='n2421' href='#n2421'>2421</a>
<a id='n2422' href='#n2422'>2422</a>
<a id='n2423' href='#n2423'>2423</a>
<a id='n2424' href='#n2424'>2424</a>
<a id='n2425' href='#n2425'>2425</a>
<a id='n2426' href='#n2426'>2426</a>
<a id='n2427' href='#n2427'>2427</a>
<a id='n2428' href='#n2428'>2428</a>
<a id='n2429' href='#n2429'>2429</a>
<a id='n2430' href='#n2430'>2430</a>
<a id='n2431' href='#n2431'>2431</a>
<a id='n2432' href='#n2432'>2432</a>
<a id='n2433' href='#n2433'>2433</a>
<a id='n2434' href='#n2434'>2434</a>
<a id='n2435' href='#n2435'>2435</a>
<a id='n2436' href='#n2436'>2436</a>
<a id='n2437' href='#n2437'>2437</a>
<a id='n2438' href='#n2438'>2438</a>
<a id='n2439' href='#n2439'>2439</a>
<a id='n2440' href='#n2440'>2440</a>
<a id='n2441' href='#n2441'>2441</a>
<a id='n2442' href='#n2442'>2442</a>
<a id='n2443' href='#n2443'>2443</a>
<a id='n2444' href='#n2444'>2444</a>
<a id='n2445' href='#n2445'>2445</a>
<a id='n2446' href='#n2446'>2446</a>
<a id='n2447' href='#n2447'>2447</a>
<a id='n2448' href='#n2448'>2448</a>
<a id='n2449' href='#n2449'>2449</a>
<a id='n2450' href='#n2450'>2450</a>
<a id='n2451' href='#n2451'>2451</a>
<a id='n2452' href='#n2452'>2452</a>
<a id='n2453' href='#n2453'>2453</a>
<a id='n2454' href='#n2454'>2454</a>
<a id='n2455' href='#n2455'>2455</a>
<a id='n2456' href='#n2456'>2456</a>
<a id='n2457' href='#n2457'>2457</a>
<a id='n2458' href='#n2458'>2458</a>
<a id='n2459' href='#n2459'>2459</a>
<a id='n2460' href='#n2460'>2460</a>
<a id='n2461' href='#n2461'>2461</a>
<a id='n2462' href='#n2462'>2462</a>
<a id='n2463' href='#n2463'>2463</a>
<a id='n2464' href='#n2464'>2464</a>
<a id='n2465' href='#n2465'>2465</a>
<a id='n2466' href='#n2466'>2466</a>
<a id='n2467' href='#n2467'>2467</a>
<a id='n2468' href='#n2468'>2468</a>
<a id='n2469' href='#n2469'>2469</a>
<a id='n2470' href='#n2470'>2470</a>
<a id='n2471' href='#n2471'>2471</a>
<a id='n2472' href='#n2472'>2472</a>
<a id='n2473' href='#n2473'>2473</a>
<a id='n2474' href='#n2474'>2474</a>
<a id='n2475' href='#n2475'>2475</a>
<a id='n2476' href='#n2476'>2476</a>
<a id='n2477' href='#n2477'>2477</a>
<a id='n2478' href='#n2478'>2478</a>
<a id='n2479' href='#n2479'>2479</a>
<a id='n2480' href='#n2480'>2480</a>
<a id='n2481' href='#n2481'>2481</a>
<a id='n2482' href='#n2482'>2482</a>
<a id='n2483' href='#n2483'>2483</a>
<a id='n2484' href='#n2484'>2484</a>
<a id='n2485' href='#n2485'>2485</a>
<a id='n2486' href='#n2486'>2486</a>
<a id='n2487' href='#n2487'>2487</a>
<a id='n2488' href='#n2488'>2488</a>
<a id='n2489' href='#n2489'>2489</a>
<a id='n2490' href='#n2490'>2490</a>
<a id='n2491' href='#n2491'>2491</a>
<a id='n2492' href='#n2492'>2492</a>
<a id='n2493' href='#n2493'>2493</a>
<a id='n2494' href='#n2494'>2494</a>
<a id='n2495' href='#n2495'>2495</a>
<a id='n2496' href='#n2496'>2496</a>
<a id='n2497' href='#n2497'>2497</a>
<a id='n2498' href='#n2498'>2498</a>
<a id='n2499' href='#n2499'>2499</a>
<a id='n2500' href='#n2500'>2500</a>
<a id='n2501' href='#n2501'>2501</a>
<a id='n2502' href='#n2502'>2502</a>
<a id='n2503' href='#n2503'>2503</a>
<a id='n2504' href='#n2504'>2504</a>
<a id='n2505' href='#n2505'>2505</a>
<a id='n2506' href='#n2506'>2506</a>
<a id='n2507' href='#n2507'>2507</a>
<a id='n2508' href='#n2508'>2508</a>
<a id='n2509' href='#n2509'>2509</a>
<a id='n2510' href='#n2510'>2510</a>
<a id='n2511' href='#n2511'>2511</a>
<a id='n2512' href='#n2512'>2512</a>
<a id='n2513' href='#n2513'>2513</a>
<a id='n2514' href='#n2514'>2514</a>
<a id='n2515' href='#n2515'>2515</a>
<a id='n2516' href='#n2516'>2516</a>
<a id='n2517' href='#n2517'>2517</a>
<a id='n2518' href='#n2518'>2518</a>
<a id='n2519' href='#n2519'>2519</a>
<a id='n2520' href='#n2520'>2520</a>
<a id='n2521' href='#n2521'>2521</a>
<a id='n2522' href='#n2522'>2522</a>
<a id='n2523' href='#n2523'>2523</a>
<a id='n2524' href='#n2524'>2524</a>
<a id='n2525' href='#n2525'>2525</a>
<a id='n2526' href='#n2526'>2526</a>
<a id='n2527' href='#n2527'>2527</a>
<a id='n2528' href='#n2528'>2528</a>
<a id='n2529' href='#n2529'>2529</a>
<a id='n2530' href='#n2530'>2530</a>
<a id='n2531' href='#n2531'>2531</a>
<a id='n2532' href='#n2532'>2532</a>
<a id='n2533' href='#n2533'>2533</a>
<a id='n2534' href='#n2534'>2534</a>
<a id='n2535' href='#n2535'>2535</a>
<a id='n2536' href='#n2536'>2536</a>
<a id='n2537' href='#n2537'>2537</a>
<a id='n2538' href='#n2538'>2538</a>
<a id='n2539' href='#n2539'>2539</a>
<a id='n2540' href='#n2540'>2540</a>
<a id='n2541' href='#n2541'>2541</a>
<a id='n2542' href='#n2542'>2542</a>
<a id='n2543' href='#n2543'>2543</a>
<a id='n2544' href='#n2544'>2544</a>
<a id='n2545' href='#n2545'>2545</a>
<a id='n2546' href='#n2546'>2546</a>
<a id='n2547' href='#n2547'>2547</a>
<a id='n2548' href='#n2548'>2548</a>
<a id='n2549' href='#n2549'>2549</a>
<a id='n2550' href='#n2550'>2550</a>
<a id='n2551' href='#n2551'>2551</a>
<a id='n2552' href='#n2552'>2552</a>
<a id='n2553' href='#n2553'>2553</a>
<a id='n2554' href='#n2554'>2554</a>
<a id='n2555' href='#n2555'>2555</a>
<a id='n2556' href='#n2556'>2556</a>
<a id='n2557' href='#n2557'>2557</a>
<a id='n2558' href='#n2558'>2558</a>
<a id='n2559' href='#n2559'>2559</a>
<a id='n2560' href='#n2560'>2560</a>
<a id='n2561' href='#n2561'>2561</a>
<a id='n2562' href='#n2562'>2562</a>
<a id='n2563' href='#n2563'>2563</a>
<a id='n2564' href='#n2564'>2564</a>
<a id='n2565' href='#n2565'>2565</a>
<a id='n2566' href='#n2566'>2566</a>
<a id='n2567' href='#n2567'>2567</a>
<a id='n2568' href='#n2568'>2568</a>
<a id='n2569' href='#n2569'>2569</a>
<a id='n2570' href='#n2570'>2570</a>
<a id='n2571' href='#n2571'>2571</a>
<a id='n2572' href='#n2572'>2572</a>
<a id='n2573' href='#n2573'>2573</a>
<a id='n2574' href='#n2574'>2574</a>
<a id='n2575' href='#n2575'>2575</a>
<a id='n2576' href='#n2576'>2576</a>
<a id='n2577' href='#n2577'>2577</a>
<a id='n2578' href='#n2578'>2578</a>
<a id='n2579' href='#n2579'>2579</a>
<a id='n2580' href='#n2580'>2580</a>
<a id='n2581' href='#n2581'>2581</a>
<a id='n2582' href='#n2582'>2582</a>
<a id='n2583' href='#n2583'>2583</a>
<a id='n2584' href='#n2584'>2584</a>
<a id='n2585' href='#n2585'>2585</a>
<a id='n2586' href='#n2586'>2586</a>
<a id='n2587' href='#n2587'>2587</a>
<a id='n2588' href='#n2588'>2588</a>
<a id='n2589' href='#n2589'>2589</a>
<a id='n2590' href='#n2590'>2590</a>
<a id='n2591' href='#n2591'>2591</a>
<a id='n2592' href='#n2592'>2592</a>
<a id='n2593' href='#n2593'>2593</a>
<a id='n2594' href='#n2594'>2594</a>
<a id='n2595' href='#n2595'>2595</a>
<a id='n2596' href='#n2596'>2596</a>
<a id='n2597' href='#n2597'>2597</a>
<a id='n2598' href='#n2598'>2598</a>
<a id='n2599' href='#n2599'>2599</a>
<a id='n2600' href='#n2600'>2600</a>
<a id='n2601' href='#n2601'>2601</a>
<a id='n2602' href='#n2602'>2602</a>
<a id='n2603' href='#n2603'>2603</a>
<a id='n2604' href='#n2604'>2604</a>
<a id='n2605' href='#n2605'>2605</a>
<a id='n2606' href='#n2606'>2606</a>
<a id='n2607' href='#n2607'>2607</a>
<a id='n2608' href='#n2608'>2608</a>
<a id='n2609' href='#n2609'>2609</a>
<a id='n2610' href='#n2610'>2610</a>
<a id='n2611' href='#n2611'>2611</a>
<a id='n2612' href='#n2612'>2612</a>
<a id='n2613' href='#n2613'>2613</a>
<a id='n2614' href='#n2614'>2614</a>
<a id='n2615' href='#n2615'>2615</a>
<a id='n2616' href='#n2616'>2616</a>
<a id='n2617' href='#n2617'>2617</a>
<a id='n2618' href='#n2618'>2618</a>
<a id='n2619' href='#n2619'>2619</a>
<a id='n2620' href='#n2620'>2620</a>
<a id='n2621' href='#n2621'>2621</a>
<a id='n2622' href='#n2622'>2622</a>
<a id='n2623' href='#n2623'>2623</a>
<a id='n2624' href='#n2624'>2624</a>
<a id='n2625' href='#n2625'>2625</a>
<a id='n2626' href='#n2626'>2626</a>
<a id='n2627' href='#n2627'>2627</a>
<a id='n2628' href='#n2628'>2628</a>
<a id='n2629' href='#n2629'>2629</a>
<a id='n2630' href='#n2630'>2630</a>
<a id='n2631' href='#n2631'>2631</a>
<a id='n2632' href='#n2632'>2632</a>
<a id='n2633' href='#n2633'>2633</a>
<a id='n2634' href='#n2634'>2634</a>
<a id='n2635' href='#n2635'>2635</a>
<a id='n2636' href='#n2636'>2636</a>
<a id='n2637' href='#n2637'>2637</a>
<a id='n2638' href='#n2638'>2638</a>
<a id='n2639' href='#n2639'>2639</a>
<a id='n2640' href='#n2640'>2640</a>
<a id='n2641' href='#n2641'>2641</a>
<a id='n2642' href='#n2642'>2642</a>
<a id='n2643' href='#n2643'>2643</a>
<a id='n2644' href='#n2644'>2644</a>
<a id='n2645' href='#n2645'>2645</a>
<a id='n2646' href='#n2646'>2646</a>
<a id='n2647' href='#n2647'>2647</a>
<a id='n2648' href='#n2648'>2648</a>
<a id='n2649' href='#n2649'>2649</a>
<a id='n2650' href='#n2650'>2650</a>
<a id='n2651' href='#n2651'>2651</a>
<a id='n2652' href='#n2652'>2652</a>
<a id='n2653' href='#n2653'>2653</a>
<a id='n2654' href='#n2654'>2654</a>
<a id='n2655' href='#n2655'>2655</a>
<a id='n2656' href='#n2656'>2656</a>
<a id='n2657' href='#n2657'>2657</a>
<a id='n2658' href='#n2658'>2658</a>
<a id='n2659' href='#n2659'>2659</a>
<a id='n2660' href='#n2660'>2660</a>
<a id='n2661' href='#n2661'>2661</a>
<a id='n2662' href='#n2662'>2662</a>
<a id='n2663' href='#n2663'>2663</a>
<a id='n2664' href='#n2664'>2664</a>
<a id='n2665' href='#n2665'>2665</a>
<a id='n2666' href='#n2666'>2666</a>
<a id='n2667' href='#n2667'>2667</a>
<a id='n2668' href='#n2668'>2668</a>
<a id='n2669' href='#n2669'>2669</a>
<a id='n2670' href='#n2670'>2670</a>
<a id='n2671' href='#n2671'>2671</a>
<a id='n2672' href='#n2672'>2672</a>
<a id='n2673' href='#n2673'>2673</a>
<a id='n2674' href='#n2674'>2674</a>
<a id='n2675' href='#n2675'>2675</a>
<a id='n2676' href='#n2676'>2676</a>
<a id='n2677' href='#n2677'>2677</a>
<a id='n2678' href='#n2678'>2678</a>
<a id='n2679' href='#n2679'>2679</a>
<a id='n2680' href='#n2680'>2680</a>
<a id='n2681' href='#n2681'>2681</a>
<a id='n2682' href='#n2682'>2682</a>
<a id='n2683' href='#n2683'>2683</a>
<a id='n2684' href='#n2684'>2684</a>
<a id='n2685' href='#n2685'>2685</a>
<a id='n2686' href='#n2686'>2686</a>
<a id='n2687' href='#n2687'>2687</a>
<a id='n2688' href='#n2688'>2688</a>
<a id='n2689' href='#n2689'>2689</a>
<a id='n2690' href='#n2690'>2690</a>
<a id='n2691' href='#n2691'>2691</a>
<a id='n2692' href='#n2692'>2692</a>
<a id='n2693' href='#n2693'>2693</a>
<a id='n2694' href='#n2694'>2694</a>
<a id='n2695' href='#n2695'>2695</a>
<a id='n2696' href='#n2696'>2696</a>
<a id='n2697' href='#n2697'>2697</a>
<a id='n2698' href='#n2698'>2698</a>
<a id='n2699' href='#n2699'>2699</a>
<a id='n2700' href='#n2700'>2700</a>
<a id='n2701' href='#n2701'>2701</a>
<a id='n2702' href='#n2702'>2702</a>
<a id='n2703' href='#n2703'>2703</a>
<a id='n2704' href='#n2704'>2704</a>
<a id='n2705' href='#n2705'>2705</a>
<a id='n2706' href='#n2706'>2706</a>
<a id='n2707' href='#n2707'>2707</a>
<a id='n2708' href='#n2708'>2708</a>
<a id='n2709' href='#n2709'>2709</a>
<a id='n2710' href='#n2710'>2710</a>
<a id='n2711' href='#n2711'>2711</a>
<a id='n2712' href='#n2712'>2712</a>
<a id='n2713' href='#n2713'>2713</a>
<a id='n2714' href='#n2714'>2714</a>
<a id='n2715' href='#n2715'>2715</a>
<a id='n2716' href='#n2716'>2716</a>
<a id='n2717' href='#n2717'>2717</a>
<a id='n2718' href='#n2718'>2718</a>
<a id='n2719' href='#n2719'>2719</a>
<a id='n2720' href='#n2720'>2720</a>
<a id='n2721' href='#n2721'>2721</a>
<a id='n2722' href='#n2722'>2722</a>
<a id='n2723' href='#n2723'>2723</a>
<a id='n2724' href='#n2724'>2724</a>
<a id='n2725' href='#n2725'>2725</a>
<a id='n2726' href='#n2726'>2726</a>
<a id='n2727' href='#n2727'>2727</a>
<a id='n2728' href='#n2728'>2728</a>
<a id='n2729' href='#n2729'>2729</a>
<a id='n2730' href='#n2730'>2730</a>
<a id='n2731' href='#n2731'>2731</a>
<a id='n2732' href='#n2732'>2732</a>
<a id='n2733' href='#n2733'>2733</a>
<a id='n2734' href='#n2734'>2734</a>
<a id='n2735' href='#n2735'>2735</a>
<a id='n2736' href='#n2736'>2736</a>
<a id='n2737' href='#n2737'>2737</a>
<a id='n2738' href='#n2738'>2738</a>
<a id='n2739' href='#n2739'>2739</a>
<a id='n2740' href='#n2740'>2740</a>
<a id='n2741' href='#n2741'>2741</a>
<a id='n2742' href='#n2742'>2742</a>
<a id='n2743' href='#n2743'>2743</a>
<a id='n2744' href='#n2744'>2744</a>
<a id='n2745' href='#n2745'>2745</a>
<a id='n2746' href='#n2746'>2746</a>
<a id='n2747' href='#n2747'>2747</a>
<a id='n2748' href='#n2748'>2748</a>
<a id='n2749' href='#n2749'>2749</a>
<a id='n2750' href='#n2750'>2750</a>
<a id='n2751' href='#n2751'>2751</a>
<a id='n2752' href='#n2752'>2752</a>
<a id='n2753' href='#n2753'>2753</a>
<a id='n2754' href='#n2754'>2754</a>
<a id='n2755' href='#n2755'>2755</a>
<a id='n2756' href='#n2756'>2756</a>
<a id='n2757' href='#n2757'>2757</a>
<a id='n2758' href='#n2758'>2758</a>
<a id='n2759' href='#n2759'>2759</a>
<a id='n2760' href='#n2760'>2760</a>
<a id='n2761' href='#n2761'>2761</a>
<a id='n2762' href='#n2762'>2762</a>
<a id='n2763' href='#n2763'>2763</a>
<a id='n2764' href='#n2764'>2764</a>
<a id='n2765' href='#n2765'>2765</a>
<a id='n2766' href='#n2766'>2766</a>
<a id='n2767' href='#n2767'>2767</a>
<a id='n2768' href='#n2768'>2768</a>
<a id='n2769' href='#n2769'>2769</a>
<a id='n2770' href='#n2770'>2770</a>
<a id='n2771' href='#n2771'>2771</a>
<a id='n2772' href='#n2772'>2772</a>
<a id='n2773' href='#n2773'>2773</a>
<a id='n2774' href='#n2774'>2774</a>
<a id='n2775' href='#n2775'>2775</a>
<a id='n2776' href='#n2776'>2776</a>
<a id='n2777' href='#n2777'>2777</a>
<a id='n2778' href='#n2778'>2778</a>
<a id='n2779' href='#n2779'>2779</a>
<a id='n2780' href='#n2780'>2780</a>
<a id='n2781' href='#n2781'>2781</a>
<a id='n2782' href='#n2782'>2782</a>
<a id='n2783' href='#n2783'>2783</a>
<a id='n2784' href='#n2784'>2784</a>
<a id='n2785' href='#n2785'>2785</a>
<a id='n2786' href='#n2786'>2786</a>
<a id='n2787' href='#n2787'>2787</a>
<a id='n2788' href='#n2788'>2788</a>
<a id='n2789' href='#n2789'>2789</a>
<a id='n2790' href='#n2790'>2790</a>
<a id='n2791' href='#n2791'>2791</a>
<a id='n2792' href='#n2792'>2792</a>
<a id='n2793' href='#n2793'>2793</a>
<a id='n2794' href='#n2794'>2794</a>
<a id='n2795' href='#n2795'>2795</a>
<a id='n2796' href='#n2796'>2796</a>
<a id='n2797' href='#n2797'>2797</a>
<a id='n2798' href='#n2798'>2798</a>
<a id='n2799' href='#n2799'>2799</a>
<a id='n2800' href='#n2800'>2800</a>
<a id='n2801' href='#n2801'>2801</a>
<a id='n2802' href='#n2802'>2802</a>
<a id='n2803' href='#n2803'>2803</a>
<a id='n2804' href='#n2804'>2804</a>
<a id='n2805' href='#n2805'>2805</a>
<a id='n2806' href='#n2806'>2806</a>
<a id='n2807' href='#n2807'>2807</a>
<a id='n2808' href='#n2808'>2808</a>
<a id='n2809' href='#n2809'>2809</a>
<a id='n2810' href='#n2810'>2810</a>
<a id='n2811' href='#n2811'>2811</a>
<a id='n2812' href='#n2812'>2812</a>
<a id='n2813' href='#n2813'>2813</a>
<a id='n2814' href='#n2814'>2814</a>
<a id='n2815' href='#n2815'>2815</a>
<a id='n2816' href='#n2816'>2816</a>
<a id='n2817' href='#n2817'>2817</a>
<a id='n2818' href='#n2818'>2818</a>
<a id='n2819' href='#n2819'>2819</a>
<a id='n2820' href='#n2820'>2820</a>
<a id='n2821' href='#n2821'>2821</a>
<a id='n2822' href='#n2822'>2822</a>
<a id='n2823' href='#n2823'>2823</a>
<a id='n2824' href='#n2824'>2824</a>
<a id='n2825' href='#n2825'>2825</a>
<a id='n2826' href='#n2826'>2826</a>
<a id='n2827' href='#n2827'>2827</a>
<a id='n2828' href='#n2828'>2828</a>
<a id='n2829' href='#n2829'>2829</a>
<a id='n2830' href='#n2830'>2830</a>
<a id='n2831' href='#n2831'>2831</a>
<a id='n2832' href='#n2832'>2832</a>
<a id='n2833' href='#n2833'>2833</a>
<a id='n2834' href='#n2834'>2834</a>
<a id='n2835' href='#n2835'>2835</a>
<a id='n2836' href='#n2836'>2836</a>
<a id='n2837' href='#n2837'>2837</a>
<a id='n2838' href='#n2838'>2838</a>
<a id='n2839' href='#n2839'>2839</a>
<a id='n2840' href='#n2840'>2840</a>
<a id='n2841' href='#n2841'>2841</a>
<a id='n2842' href='#n2842'>2842</a>
<a id='n2843' href='#n2843'>2843</a>
<a id='n2844' href='#n2844'>2844</a>
<a id='n2845' href='#n2845'>2845</a>
<a id='n2846' href='#n2846'>2846</a>
<a id='n2847' href='#n2847'>2847</a>
<a id='n2848' href='#n2848'>2848</a>
<a id='n2849' href='#n2849'>2849</a>
<a id='n2850' href='#n2850'>2850</a>
<a id='n2851' href='#n2851'>2851</a>
<a id='n2852' href='#n2852'>2852</a>
<a id='n2853' href='#n2853'>2853</a>
<a id='n2854' href='#n2854'>2854</a>
<a id='n2855' href='#n2855'>2855</a>
<a id='n2856' href='#n2856'>2856</a>
<a id='n2857' href='#n2857'>2857</a>
<a id='n2858' href='#n2858'>2858</a>
<a id='n2859' href='#n2859'>2859</a>
<a id='n2860' href='#n2860'>2860</a>
<a id='n2861' href='#n2861'>2861</a>
<a id='n2862' href='#n2862'>2862</a>
<a id='n2863' href='#n2863'>2863</a>
<a id='n2864' href='#n2864'>2864</a>
<a id='n2865' href='#n2865'>2865</a>
<a id='n2866' href='#n2866'>2866</a>
<a id='n2867' href='#n2867'>2867</a>
<a id='n2868' href='#n2868'>2868</a>
<a id='n2869' href='#n2869'>2869</a>
<a id='n2870' href='#n2870'>2870</a>
<a id='n2871' href='#n2871'>2871</a>
<a id='n2872' href='#n2872'>2872</a>
<a id='n2873' href='#n2873'>2873</a>
<a id='n2874' href='#n2874'>2874</a>
<a id='n2875' href='#n2875'>2875</a>
<a id='n2876' href='#n2876'>2876</a>
<a id='n2877' href='#n2877'>2877</a>
<a id='n2878' href='#n2878'>2878</a>
<a id='n2879' href='#n2879'>2879</a>
<a id='n2880' href='#n2880'>2880</a>
<a id='n2881' href='#n2881'>2881</a>
<a id='n2882' href='#n2882'>2882</a>
<a id='n2883' href='#n2883'>2883</a>
<a id='n2884' href='#n2884'>2884</a>
<a id='n2885' href='#n2885'>2885</a>
<a id='n2886' href='#n2886'>2886</a>
<a id='n2887' href='#n2887'>2887</a>
<a id='n2888' href='#n2888'>2888</a>
<a id='n2889' href='#n2889'>2889</a>
<a id='n2890' href='#n2890'>2890</a>
<a id='n2891' href='#n2891'>2891</a>
<a id='n2892' href='#n2892'>2892</a>
<a id='n2893' href='#n2893'>2893</a>
<a id='n2894' href='#n2894'>2894</a>
<a id='n2895' href='#n2895'>2895</a>
<a id='n2896' href='#n2896'>2896</a>
<a id='n2897' href='#n2897'>2897</a>
<a id='n2898' href='#n2898'>2898</a>
<a id='n2899' href='#n2899'>2899</a>
<a id='n2900' href='#n2900'>2900</a>
<a id='n2901' href='#n2901'>2901</a>
<a id='n2902' href='#n2902'>2902</a>
<a id='n2903' href='#n2903'>2903</a>
<a id='n2904' href='#n2904'>2904</a>
<a id='n2905' href='#n2905'>2905</a>
<a id='n2906' href='#n2906'>2906</a>
<a id='n2907' href='#n2907'>2907</a>
<a id='n2908' href='#n2908'>2908</a>
<a id='n2909' href='#n2909'>2909</a>
<a id='n2910' href='#n2910'>2910</a>
<a id='n2911' href='#n2911'>2911</a>
<a id='n2912' href='#n2912'>2912</a>
<a id='n2913' href='#n2913'>2913</a>
<a id='n2914' href='#n2914'>2914</a>
<a id='n2915' href='#n2915'>2915</a>
<a id='n2916' href='#n2916'>2916</a>
<a id='n2917' href='#n2917'>2917</a>
<a id='n2918' href='#n2918'>2918</a>
<a id='n2919' href='#n2919'>2919</a>
<a id='n2920' href='#n2920'>2920</a>
<a id='n2921' href='#n2921'>2921</a>
<a id='n2922' href='#n2922'>2922</a>
<a id='n2923' href='#n2923'>2923</a>
<a id='n2924' href='#n2924'>2924</a>
<a id='n2925' href='#n2925'>2925</a>
<a id='n2926' href='#n2926'>2926</a>
<a id='n2927' href='#n2927'>2927</a>
<a id='n2928' href='#n2928'>2928</a>
<a id='n2929' href='#n2929'>2929</a>
<a id='n2930' href='#n2930'>2930</a>
<a id='n2931' href='#n2931'>2931</a>
<a id='n2932' href='#n2932'>2932</a>
<a id='n2933' href='#n2933'>2933</a>
<a id='n2934' href='#n2934'>2934</a>
<a id='n2935' href='#n2935'>2935</a>
<a id='n2936' href='#n2936'>2936</a>
<a id='n2937' href='#n2937'>2937</a>
<a id='n2938' href='#n2938'>2938</a>
<a id='n2939' href='#n2939'>2939</a>
<a id='n2940' href='#n2940'>2940</a>
<a id='n2941' href='#n2941'>2941</a>
<a id='n2942' href='#n2942'>2942</a>
<a id='n2943' href='#n2943'>2943</a>
<a id='n2944' href='#n2944'>2944</a>
<a id='n2945' href='#n2945'>2945</a>
<a id='n2946' href='#n2946'>2946</a>
<a id='n2947' href='#n2947'>2947</a>
<a id='n2948' href='#n2948'>2948</a>
<a id='n2949' href='#n2949'>2949</a>
<a id='n2950' href='#n2950'>2950</a>
<a id='n2951' href='#n2951'>2951</a>
<a id='n2952' href='#n2952'>2952</a>
<a id='n2953' href='#n2953'>2953</a>
<a id='n2954' href='#n2954'>2954</a>
<a id='n2955' href='#n2955'>2955</a>
<a id='n2956' href='#n2956'>2956</a>
<a id='n2957' href='#n2957'>2957</a>
<a id='n2958' href='#n2958'>2958</a>
<a id='n2959' href='#n2959'>2959</a>
<a id='n2960' href='#n2960'>2960</a>
<a id='n2961' href='#n2961'>2961</a>
<a id='n2962' href='#n2962'>2962</a>
<a id='n2963' href='#n2963'>2963</a>
<a id='n2964' href='#n2964'>2964</a>
<a id='n2965' href='#n2965'>2965</a>
<a id='n2966' href='#n2966'>2966</a>
<a id='n2967' href='#n2967'>2967</a>
<a id='n2968' href='#n2968'>2968</a>
<a id='n2969' href='#n2969'>2969</a>
<a id='n2970' href='#n2970'>2970</a>
<a id='n2971' href='#n2971'>2971</a>
<a id='n2972' href='#n2972'>2972</a>
<a id='n2973' href='#n2973'>2973</a>
<a id='n2974' href='#n2974'>2974</a>
<a id='n2975' href='#n2975'>2975</a>
<a id='n2976' href='#n2976'>2976</a>
<a id='n2977' href='#n2977'>2977</a>
<a id='n2978' href='#n2978'>2978</a>
<a id='n2979' href='#n2979'>2979</a>
<a id='n2980' href='#n2980'>2980</a>
<a id='n2981' href='#n2981'>2981</a>
<a id='n2982' href='#n2982'>2982</a>
<a id='n2983' href='#n2983'>2983</a>
<a id='n2984' href='#n2984'>2984</a>
<a id='n2985' href='#n2985'>2985</a>
<a id='n2986' href='#n2986'>2986</a>
<a id='n2987' href='#n2987'>2987</a>
<a id='n2988' href='#n2988'>2988</a>
<a id='n2989' href='#n2989'>2989</a>
<a id='n2990' href='#n2990'>2990</a>
<a id='n2991' href='#n2991'>2991</a>
<a id='n2992' href='#n2992'>2992</a>
<a id='n2993' href='#n2993'>2993</a>
<a id='n2994' href='#n2994'>2994</a>
<a id='n2995' href='#n2995'>2995</a>
<a id='n2996' href='#n2996'>2996</a>
<a id='n2997' href='#n2997'>2997</a>
<a id='n2998' href='#n2998'>2998</a>
<a id='n2999' href='#n2999'>2999</a>
<a id='n3000' href='#n3000'>3000</a>
<a id='n3001' href='#n3001'>3001</a>
<a id='n3002' href='#n3002'>3002</a>
<a id='n3003' href='#n3003'>3003</a>
<a id='n3004' href='#n3004'>3004</a>
<a id='n3005' href='#n3005'>3005</a>
<a id='n3006' href='#n3006'>3006</a>
<a id='n3007' href='#n3007'>3007</a>
<a id='n3008' href='#n3008'>3008</a>
<a id='n3009' href='#n3009'>3009</a>
<a id='n3010' href='#n3010'>3010</a>
<a id='n3011' href='#n3011'>3011</a>
<a id='n3012' href='#n3012'>3012</a>
<a id='n3013' href='#n3013'>3013</a>
<a id='n3014' href='#n3014'>3014</a>
<a id='n3015' href='#n3015'>3015</a>
<a id='n3016' href='#n3016'>3016</a>
<a id='n3017' href='#n3017'>3017</a>
<a id='n3018' href='#n3018'>3018</a>
<a id='n3019' href='#n3019'>3019</a>
<a id='n3020' href='#n3020'>3020</a>
<a id='n3021' href='#n3021'>3021</a>
<a id='n3022' href='#n3022'>3022</a>
<a id='n3023' href='#n3023'>3023</a>
<a id='n3024' href='#n3024'>3024</a>
<a id='n3025' href='#n3025'>3025</a>
<a id='n3026' href='#n3026'>3026</a>
<a id='n3027' href='#n3027'>3027</a>
<a id='n3028' href='#n3028'>3028</a>
<a id='n3029' href='#n3029'>3029</a>
<a id='n3030' href='#n3030'>3030</a>
<a id='n3031' href='#n3031'>3031</a>
<a id='n3032' href='#n3032'>3032</a>
<a id='n3033' href='#n3033'>3033</a>
<a id='n3034' href='#n3034'>3034</a>
<a id='n3035' href='#n3035'>3035</a>
<a id='n3036' href='#n3036'>3036</a>
<a id='n3037' href='#n3037'>3037</a>
<a id='n3038' href='#n3038'>3038</a>
<a id='n3039' href='#n3039'>3039</a>
<a id='n3040' href='#n3040'>3040</a>
<a id='n3041' href='#n3041'>3041</a>
<a id='n3042' href='#n3042'>3042</a>
<a id='n3043' href='#n3043'>3043</a>
<a id='n3044' href='#n3044'>3044</a>
<a id='n3045' href='#n3045'>3045</a>
<a id='n3046' href='#n3046'>3046</a>
<a id='n3047' href='#n3047'>3047</a>
<a id='n3048' href='#n3048'>3048</a>
<a id='n3049' href='#n3049'>3049</a>
<a id='n3050' href='#n3050'>3050</a>
<a id='n3051' href='#n3051'>3051</a>
<a id='n3052' href='#n3052'>3052</a>
<a id='n3053' href='#n3053'>3053</a>
<a id='n3054' href='#n3054'>3054</a>
<a id='n3055' href='#n3055'>3055</a>
<a id='n3056' href='#n3056'>3056</a>
<a id='n3057' href='#n3057'>3057</a>
<a id='n3058' href='#n3058'>3058</a>
<a id='n3059' href='#n3059'>3059</a>
<a id='n3060' href='#n3060'>3060</a>
<a id='n3061' href='#n3061'>3061</a>
<a id='n3062' href='#n3062'>3062</a>
<a id='n3063' href='#n3063'>3063</a>
<a id='n3064' href='#n3064'>3064</a>
<a id='n3065' href='#n3065'>3065</a>
<a id='n3066' href='#n3066'>3066</a>
<a id='n3067' href='#n3067'>3067</a>
<a id='n3068' href='#n3068'>3068</a>
<a id='n3069' href='#n3069'>3069</a>
<a id='n3070' href='#n3070'>3070</a>
<a id='n3071' href='#n3071'>3071</a>
<a id='n3072' href='#n3072'>3072</a>
<a id='n3073' href='#n3073'>3073</a>
<a id='n3074' href='#n3074'>3074</a>
<a id='n3075' href='#n3075'>3075</a>
<a id='n3076' href='#n3076'>3076</a>
<a id='n3077' href='#n3077'>3077</a>
<a id='n3078' href='#n3078'>3078</a>
<a id='n3079' href='#n3079'>3079</a>
<a id='n3080' href='#n3080'>3080</a>
<a id='n3081' href='#n3081'>3081</a>
<a id='n3082' href='#n3082'>3082</a>
<a id='n3083' href='#n3083'>3083</a>
<a id='n3084' href='#n3084'>3084</a>
<a id='n3085' href='#n3085'>3085</a>
<a id='n3086' href='#n3086'>3086</a>
<a id='n3087' href='#n3087'>3087</a>
<a id='n3088' href='#n3088'>3088</a>
<a id='n3089' href='#n3089'>3089</a>
<a id='n3090' href='#n3090'>3090</a>
<a id='n3091' href='#n3091'>3091</a>
<a id='n3092' href='#n3092'>3092</a>
<a id='n3093' href='#n3093'>3093</a>
<a id='n3094' href='#n3094'>3094</a>
<a id='n3095' href='#n3095'>3095</a>
<a id='n3096' href='#n3096'>3096</a>
<a id='n3097' href='#n3097'>3097</a>
<a id='n3098' href='#n3098'>3098</a>
<a id='n3099' href='#n3099'>3099</a>
<a id='n3100' href='#n3100'>3100</a>
<a id='n3101' href='#n3101'>3101</a>
<a id='n3102' href='#n3102'>3102</a>
<a id='n3103' href='#n3103'>3103</a>
<a id='n3104' href='#n3104'>3104</a>
<a id='n3105' href='#n3105'>3105</a>
<a id='n3106' href='#n3106'>3106</a>
<a id='n3107' href='#n3107'>3107</a>
<a id='n3108' href='#n3108'>3108</a>
<a id='n3109' href='#n3109'>3109</a>
<a id='n3110' href='#n3110'>3110</a>
<a id='n3111' href='#n3111'>3111</a>
<a id='n3112' href='#n3112'>3112</a>
<a id='n3113' href='#n3113'>3113</a>
<a id='n3114' href='#n3114'>3114</a>
<a id='n3115' href='#n3115'>3115</a>
<a id='n3116' href='#n3116'>3116</a>
<a id='n3117' href='#n3117'>3117</a>
<a id='n3118' href='#n3118'>3118</a>
<a id='n3119' href='#n3119'>3119</a>
<a id='n3120' href='#n3120'>3120</a>
<a id='n3121' href='#n3121'>3121</a>
<a id='n3122' href='#n3122'>3122</a>
<a id='n3123' href='#n3123'>3123</a>
<a id='n3124' href='#n3124'>3124</a>
<a id='n3125' href='#n3125'>3125</a>
<a id='n3126' href='#n3126'>3126</a>
<a id='n3127' href='#n3127'>3127</a>
<a id='n3128' href='#n3128'>3128</a>
<a id='n3129' href='#n3129'>3129</a>
<a id='n3130' href='#n3130'>3130</a>
<a id='n3131' href='#n3131'>3131</a>
<a id='n3132' href='#n3132'>3132</a>
<a id='n3133' href='#n3133'>3133</a>
<a id='n3134' href='#n3134'>3134</a>
<a id='n3135' href='#n3135'>3135</a>
<a id='n3136' href='#n3136'>3136</a>
<a id='n3137' href='#n3137'>3137</a>
<a id='n3138' href='#n3138'>3138</a>
<a id='n3139' href='#n3139'>3139</a>
<a id='n3140' href='#n3140'>3140</a>
<a id='n3141' href='#n3141'>3141</a>
<a id='n3142' href='#n3142'>3142</a>
<a id='n3143' href='#n3143'>3143</a>
<a id='n3144' href='#n3144'>3144</a>
<a id='n3145' href='#n3145'>3145</a>
<a id='n3146' href='#n3146'>3146</a>
<a id='n3147' href='#n3147'>3147</a>
<a id='n3148' href='#n3148'>3148</a>
<a id='n3149' href='#n3149'>3149</a>
<a id='n3150' href='#n3150'>3150</a>
<a id='n3151' href='#n3151'>3151</a>
<a id='n3152' href='#n3152'>3152</a>
<a id='n3153' href='#n3153'>3153</a>
<a id='n3154' href='#n3154'>3154</a>
<a id='n3155' href='#n3155'>3155</a>
<a id='n3156' href='#n3156'>3156</a>
<a id='n3157' href='#n3157'>3157</a>
<a id='n3158' href='#n3158'>3158</a>
<a id='n3159' href='#n3159'>3159</a>
<a id='n3160' href='#n3160'>3160</a>
<a id='n3161' href='#n3161'>3161</a>
<a id='n3162' href='#n3162'>3162</a>
<a id='n3163' href='#n3163'>3163</a>
<a id='n3164' href='#n3164'>3164</a>
<a id='n3165' href='#n3165'>3165</a>
<a id='n3166' href='#n3166'>3166</a>
<a id='n3167' href='#n3167'>3167</a>
<a id='n3168' href='#n3168'>3168</a>
<a id='n3169' href='#n3169'>3169</a>
<a id='n3170' href='#n3170'>3170</a>
<a id='n3171' href='#n3171'>3171</a>
<a id='n3172' href='#n3172'>3172</a>
<a id='n3173' href='#n3173'>3173</a>
<a id='n3174' href='#n3174'>3174</a>
<a id='n3175' href='#n3175'>3175</a>
<a id='n3176' href='#n3176'>3176</a>
<a id='n3177' href='#n3177'>3177</a>
<a id='n3178' href='#n3178'>3178</a>
<a id='n3179' href='#n3179'>3179</a>
<a id='n3180' href='#n3180'>3180</a>
<a id='n3181' href='#n3181'>3181</a>
<a id='n3182' href='#n3182'>3182</a>
<a id='n3183' href='#n3183'>3183</a>
<a id='n3184' href='#n3184'>3184</a>
<a id='n3185' href='#n3185'>3185</a>
<a id='n3186' href='#n3186'>3186</a>
<a id='n3187' href='#n3187'>3187</a>
<a id='n3188' href='#n3188'>3188</a>
<a id='n3189' href='#n3189'>3189</a>
<a id='n3190' href='#n3190'>3190</a>
<a id='n3191' href='#n3191'>3191</a>
<a id='n3192' href='#n3192'>3192</a>
<a id='n3193' href='#n3193'>3193</a>
<a id='n3194' href='#n3194'>3194</a>
<a id='n3195' href='#n3195'>3195</a>
<a id='n3196' href='#n3196'>3196</a>
<a id='n3197' href='#n3197'>3197</a>
<a id='n3198' href='#n3198'>3198</a>
<a id='n3199' href='#n3199'>3199</a>
<a id='n3200' href='#n3200'>3200</a>
<a id='n3201' href='#n3201'>3201</a>
<a id='n3202' href='#n3202'>3202</a>
<a id='n3203' href='#n3203'>3203</a>
<a id='n3204' href='#n3204'>3204</a>
<a id='n3205' href='#n3205'>3205</a>
<a id='n3206' href='#n3206'>3206</a>
<a id='n3207' href='#n3207'>3207</a>
<a id='n3208' href='#n3208'>3208</a>
<a id='n3209' href='#n3209'>3209</a>
<a id='n3210' href='#n3210'>3210</a>
<a id='n3211' href='#n3211'>3211</a>
<a id='n3212' href='#n3212'>3212</a>
<a id='n3213' href='#n3213'>3213</a>
<a id='n3214' href='#n3214'>3214</a>
<a id='n3215' href='#n3215'>3215</a>
<a id='n3216' href='#n3216'>3216</a>
<a id='n3217' href='#n3217'>3217</a>
<a id='n3218' href='#n3218'>3218</a>
<a id='n3219' href='#n3219'>3219</a>
<a id='n3220' href='#n3220'>3220</a>
<a id='n3221' href='#n3221'>3221</a>
<a id='n3222' href='#n3222'>3222</a>
<a id='n3223' href='#n3223'>3223</a>
<a id='n3224' href='#n3224'>3224</a>
<a id='n3225' href='#n3225'>3225</a>
<a id='n3226' href='#n3226'>3226</a>
<a id='n3227' href='#n3227'>3227</a>
<a id='n3228' href='#n3228'>3228</a>
<a id='n3229' href='#n3229'>3229</a>
<a id='n3230' href='#n3230'>3230</a>
<a id='n3231' href='#n3231'>3231</a>
<a id='n3232' href='#n3232'>3232</a>
<a id='n3233' href='#n3233'>3233</a>
<a id='n3234' href='#n3234'>3234</a>
<a id='n3235' href='#n3235'>3235</a>
<a id='n3236' href='#n3236'>3236</a>
<a id='n3237' href='#n3237'>3237</a>
<a id='n3238' href='#n3238'>3238</a>
<a id='n3239' href='#n3239'>3239</a>
<a id='n3240' href='#n3240'>3240</a>
<a id='n3241' href='#n3241'>3241</a>
<a id='n3242' href='#n3242'>3242</a>
<a id='n3243' href='#n3243'>3243</a>
<a id='n3244' href='#n3244'>3244</a>
<a id='n3245' href='#n3245'>3245</a>
<a id='n3246' href='#n3246'>3246</a>
<a id='n3247' href='#n3247'>3247</a>
<a id='n3248' href='#n3248'>3248</a>
<a id='n3249' href='#n3249'>3249</a>
<a id='n3250' href='#n3250'>3250</a>
<a id='n3251' href='#n3251'>3251</a>
<a id='n3252' href='#n3252'>3252</a>
<a id='n3253' href='#n3253'>3253</a>
<a id='n3254' href='#n3254'>3254</a>
<a id='n3255' href='#n3255'>3255</a>
<a id='n3256' href='#n3256'>3256</a>
<a id='n3257' href='#n3257'>3257</a>
<a id='n3258' href='#n3258'>3258</a>
<a id='n3259' href='#n3259'>3259</a>
<a id='n3260' href='#n3260'>3260</a>
<a id='n3261' href='#n3261'>3261</a>
<a id='n3262' href='#n3262'>3262</a>
<a id='n3263' href='#n3263'>3263</a>
<a id='n3264' href='#n3264'>3264</a>
<a id='n3265' href='#n3265'>3265</a>
<a id='n3266' href='#n3266'>3266</a>
<a id='n3267' href='#n3267'>3267</a>
<a id='n3268' href='#n3268'>3268</a>
<a id='n3269' href='#n3269'>3269</a>
<a id='n3270' href='#n3270'>3270</a>
<a id='n3271' href='#n3271'>3271</a>
<a id='n3272' href='#n3272'>3272</a>
<a id='n3273' href='#n3273'>3273</a>
<a id='n3274' href='#n3274'>3274</a>
<a id='n3275' href='#n3275'>3275</a>
<a id='n3276' href='#n3276'>3276</a>
<a id='n3277' href='#n3277'>3277</a>
<a id='n3278' href='#n3278'>3278</a>
<a id='n3279' href='#n3279'>3279</a>
<a id='n3280' href='#n3280'>3280</a>
<a id='n3281' href='#n3281'>3281</a>
<a id='n3282' href='#n3282'>3282</a>
<a id='n3283' href='#n3283'>3283</a>
<a id='n3284' href='#n3284'>3284</a>
<a id='n3285' href='#n3285'>3285</a>
<a id='n3286' href='#n3286'>3286</a>
<a id='n3287' href='#n3287'>3287</a>
<a id='n3288' href='#n3288'>3288</a>
<a id='n3289' href='#n3289'>3289</a>
<a id='n3290' href='#n3290'>3290</a>
<a id='n3291' href='#n3291'>3291</a>
<a id='n3292' href='#n3292'>3292</a>
<a id='n3293' href='#n3293'>3293</a>
<a id='n3294' href='#n3294'>3294</a>
<a id='n3295' href='#n3295'>3295</a>
<a id='n3296' href='#n3296'>3296</a>
<a id='n3297' href='#n3297'>3297</a>
<a id='n3298' href='#n3298'>3298</a>
<a id='n3299' href='#n3299'>3299</a>
<a id='n3300' href='#n3300'>3300</a>
<a id='n3301' href='#n3301'>3301</a>
<a id='n3302' href='#n3302'>3302</a>
<a id='n3303' href='#n3303'>3303</a>
<a id='n3304' href='#n3304'>3304</a>
<a id='n3305' href='#n3305'>3305</a>
<a id='n3306' href='#n3306'>3306</a>
<a id='n3307' href='#n3307'>3307</a>
<a id='n3308' href='#n3308'>3308</a>
<a id='n3309' href='#n3309'>3309</a>
<a id='n3310' href='#n3310'>3310</a>
<a id='n3311' href='#n3311'>3311</a>
<a id='n3312' href='#n3312'>3312</a>
<a id='n3313' href='#n3313'>3313</a>
<a id='n3314' href='#n3314'>3314</a>
<a id='n3315' href='#n3315'>3315</a>
<a id='n3316' href='#n3316'>3316</a>
<a id='n3317' href='#n3317'>3317</a>
<a id='n3318' href='#n3318'>3318</a>
<a id='n3319' href='#n3319'>3319</a>
<a id='n3320' href='#n3320'>3320</a>
<a id='n3321' href='#n3321'>3321</a>
<a id='n3322' href='#n3322'>3322</a>
<a id='n3323' href='#n3323'>3323</a>
<a id='n3324' href='#n3324'>3324</a>
<a id='n3325' href='#n3325'>3325</a>
<a id='n3326' href='#n3326'>3326</a>
<a id='n3327' href='#n3327'>3327</a>
<a id='n3328' href='#n3328'>3328</a>
<a id='n3329' href='#n3329'>3329</a>
<a id='n3330' href='#n3330'>3330</a>
<a id='n3331' href='#n3331'>3331</a>
<a id='n3332' href='#n3332'>3332</a>
<a id='n3333' href='#n3333'>3333</a>
<a id='n3334' href='#n3334'>3334</a>
<a id='n3335' href='#n3335'>3335</a>
<a id='n3336' href='#n3336'>3336</a>
<a id='n3337' href='#n3337'>3337</a>
<a id='n3338' href='#n3338'>3338</a>
<a id='n3339' href='#n3339'>3339</a>
<a id='n3340' href='#n3340'>3340</a>
<a id='n3341' href='#n3341'>3341</a>
<a id='n3342' href='#n3342'>3342</a>
<a id='n3343' href='#n3343'>3343</a>
<a id='n3344' href='#n3344'>3344</a>
<a id='n3345' href='#n3345'>3345</a>
<a id='n3346' href='#n3346'>3346</a>
<a id='n3347' href='#n3347'>3347</a>
<a id='n3348' href='#n3348'>3348</a>
<a id='n3349' href='#n3349'>3349</a>
<a id='n3350' href='#n3350'>3350</a>
<a id='n3351' href='#n3351'>3351</a>
<a id='n3352' href='#n3352'>3352</a>
<a id='n3353' href='#n3353'>3353</a>
<a id='n3354' href='#n3354'>3354</a>
<a id='n3355' href='#n3355'>3355</a>
<a id='n3356' href='#n3356'>3356</a>
<a id='n3357' href='#n3357'>3357</a>
<a id='n3358' href='#n3358'>3358</a>
<a id='n3359' href='#n3359'>3359</a>
<a id='n3360' href='#n3360'>3360</a>
<a id='n3361' href='#n3361'>3361</a>
<a id='n3362' href='#n3362'>3362</a>
<a id='n3363' href='#n3363'>3363</a>
<a id='n3364' href='#n3364'>3364</a>
<a id='n3365' href='#n3365'>3365</a>
<a id='n3366' href='#n3366'>3366</a>
<a id='n3367' href='#n3367'>3367</a>
<a id='n3368' href='#n3368'>3368</a>
<a id='n3369' href='#n3369'>3369</a>
<a id='n3370' href='#n3370'>3370</a>
<a id='n3371' href='#n3371'>3371</a>
<a id='n3372' href='#n3372'>3372</a>
<a id='n3373' href='#n3373'>3373</a>
<a id='n3374' href='#n3374'>3374</a>
<a id='n3375' href='#n3375'>3375</a>
<a id='n3376' href='#n3376'>3376</a>
<a id='n3377' href='#n3377'>3377</a>
<a id='n3378' href='#n3378'>3378</a>
<a id='n3379' href='#n3379'>3379</a>
<a id='n3380' href='#n3380'>3380</a>
<a id='n3381' href='#n3381'>3381</a>
<a id='n3382' href='#n3382'>3382</a>
<a id='n3383' href='#n3383'>3383</a>
<a id='n3384' href='#n3384'>3384</a>
<a id='n3385' href='#n3385'>3385</a>
<a id='n3386' href='#n3386'>3386</a>
<a id='n3387' href='#n3387'>3387</a>
<a id='n3388' href='#n3388'>3388</a>
<a id='n3389' href='#n3389'>3389</a>
<a id='n3390' href='#n3390'>3390</a>
<a id='n3391' href='#n3391'>3391</a>
<a id='n3392' href='#n3392'>3392</a>
<a id='n3393' href='#n3393'>3393</a>
<a id='n3394' href='#n3394'>3394</a>
<a id='n3395' href='#n3395'>3395</a>
<a id='n3396' href='#n3396'>3396</a>
<a id='n3397' href='#n3397'>3397</a>
<a id='n3398' href='#n3398'>3398</a>
<a id='n3399' href='#n3399'>3399</a>
<a id='n3400' href='#n3400'>3400</a>
<a id='n3401' href='#n3401'>3401</a>
<a id='n3402' href='#n3402'>3402</a>
<a id='n3403' href='#n3403'>3403</a>
<a id='n3404' href='#n3404'>3404</a>
<a id='n3405' href='#n3405'>3405</a>
<a id='n3406' href='#n3406'>3406</a>
<a id='n3407' href='#n3407'>3407</a>
<a id='n3408' href='#n3408'>3408</a>
<a id='n3409' href='#n3409'>3409</a>
<a id='n3410' href='#n3410'>3410</a>
<a id='n3411' href='#n3411'>3411</a>
<a id='n3412' href='#n3412'>3412</a>
<a id='n3413' href='#n3413'>3413</a>
<a id='n3414' href='#n3414'>3414</a>
<a id='n3415' href='#n3415'>3415</a>
<a id='n3416' href='#n3416'>3416</a>
<a id='n3417' href='#n3417'>3417</a>
<a id='n3418' href='#n3418'>3418</a>
<a id='n3419' href='#n3419'>3419</a>
<a id='n3420' href='#n3420'>3420</a>
<a id='n3421' href='#n3421'>3421</a>
<a id='n3422' href='#n3422'>3422</a>
<a id='n3423' href='#n3423'>3423</a>
<a id='n3424' href='#n3424'>3424</a>
<a id='n3425' href='#n3425'>3425</a>
<a id='n3426' href='#n3426'>3426</a>
<a id='n3427' href='#n3427'>3427</a>
<a id='n3428' href='#n3428'>3428</a>
<a id='n3429' href='#n3429'>3429</a>
<a id='n3430' href='#n3430'>3430</a>
<a id='n3431' href='#n3431'>3431</a>
<a id='n3432' href='#n3432'>3432</a>
<a id='n3433' href='#n3433'>3433</a>
<a id='n3434' href='#n3434'>3434</a>
<a id='n3435' href='#n3435'>3435</a>
<a id='n3436' href='#n3436'>3436</a>
<a id='n3437' href='#n3437'>3437</a>
<a id='n3438' href='#n3438'>3438</a>
<a id='n3439' href='#n3439'>3439</a>
<a id='n3440' href='#n3440'>3440</a>
<a id='n3441' href='#n3441'>3441</a>
<a id='n3442' href='#n3442'>3442</a>
<a id='n3443' href='#n3443'>3443</a>
<a id='n3444' href='#n3444'>3444</a>
<a id='n3445' href='#n3445'>3445</a>
<a id='n3446' href='#n3446'>3446</a>
<a id='n3447' href='#n3447'>3447</a>
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<a id='n3523' href='#n3523'>3523</a>
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<a id='n3608' href='#n3608'>3608</a>
<a id='n3609' href='#n3609'>3609</a>
<a id='n3610' href='#n3610'>3610</a>
<a id='n3611' href='#n3611'>3611</a>
<a id='n3612' href='#n3612'>3612</a>
<a id='n3613' href='#n3613'>3613</a>
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<a id='n3620' href='#n3620'>3620</a>
<a id='n3621' href='#n3621'>3621</a>
<a id='n3622' href='#n3622'>3622</a>
<a id='n3623' href='#n3623'>3623</a>
<a id='n3624' href='#n3624'>3624</a>
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<a id='n3631' href='#n3631'>3631</a>
<a id='n3632' href='#n3632'>3632</a>
<a id='n3633' href='#n3633'>3633</a>
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<a id='n3639' href='#n3639'>3639</a>
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<a id='n3641' href='#n3641'>3641</a>
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<a id='n3644' href='#n3644'>3644</a>
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<a id='n3648' href='#n3648'>3648</a>
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<a id='n3687' href='#n3687'>3687</a>
<a id='n3688' href='#n3688'>3688</a>
<a id='n3689' href='#n3689'>3689</a>
<a id='n3690' href='#n3690'>3690</a>
<a id='n3691' href='#n3691'>3691</a>
<a id='n3692' href='#n3692'>3692</a>
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<a id='n3700' href='#n3700'>3700</a>
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<a id='n3703' href='#n3703'>3703</a>
<a id='n3704' href='#n3704'>3704</a>
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<a id='n3708' href='#n3708'>3708</a>
<a id='n3709' href='#n3709'>3709</a>
<a id='n3710' href='#n3710'>3710</a>
<a id='n3711' href='#n3711'>3711</a>
<a id='n3712' href='#n3712'>3712</a>
<a id='n3713' href='#n3713'>3713</a>
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<a id='n3721' href='#n3721'>3721</a>
<a id='n3722' href='#n3722'>3722</a>
<a id='n3723' href='#n3723'>3723</a>
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<a id='n3731' href='#n3731'>3731</a>
<a id='n3732' href='#n3732'>3732</a>
<a id='n3733' href='#n3733'>3733</a>
<a id='n3734' href='#n3734'>3734</a>
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<a id='n3760' href='#n3760'>3760</a>
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<a id='n3763' href='#n3763'>3763</a>
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<a id='n3787' href='#n3787'>3787</a>
<a id='n3788' href='#n3788'>3788</a>
<a id='n3789' href='#n3789'>3789</a>
<a id='n3790' href='#n3790'>3790</a>
<a id='n3791' href='#n3791'>3791</a>
<a id='n3792' href='#n3792'>3792</a>
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<a id='n3798' href='#n3798'>3798</a>
<a id='n3799' href='#n3799'>3799</a>
<a id='n3800' href='#n3800'>3800</a>
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<a id='n3802' href='#n3802'>3802</a>
<a id='n3803' href='#n3803'>3803</a>
<a id='n3804' href='#n3804'>3804</a>
<a id='n3805' href='#n3805'>3805</a>
<a id='n3806' href='#n3806'>3806</a>
<a id='n3807' href='#n3807'>3807</a>
<a id='n3808' href='#n3808'>3808</a>
<a id='n3809' href='#n3809'>3809</a>
<a id='n3810' href='#n3810'>3810</a>
<a id='n3811' href='#n3811'>3811</a>
<a id='n3812' href='#n3812'>3812</a>
<a id='n3813' href='#n3813'>3813</a>
<a id='n3814' href='#n3814'>3814</a>
<a id='n3815' href='#n3815'>3815</a>
<a id='n3816' href='#n3816'>3816</a>
<a id='n3817' href='#n3817'>3817</a>
<a id='n3818' href='#n3818'>3818</a>
<a id='n3819' href='#n3819'>3819</a>
<a id='n3820' href='#n3820'>3820</a>
<a id='n3821' href='#n3821'>3821</a>
<a id='n3822' href='#n3822'>3822</a>
<a id='n3823' href='#n3823'>3823</a>
<a id='n3824' href='#n3824'>3824</a>
<a id='n3825' href='#n3825'>3825</a>
<a id='n3826' href='#n3826'>3826</a>
<a id='n3827' href='#n3827'>3827</a>
<a id='n3828' href='#n3828'>3828</a>
<a id='n3829' href='#n3829'>3829</a>
<a id='n3830' href='#n3830'>3830</a>
<a id='n3831' href='#n3831'>3831</a>
<a id='n3832' href='#n3832'>3832</a>
<a id='n3833' href='#n3833'>3833</a>
<a id='n3834' href='#n3834'>3834</a>
<a id='n3835' href='#n3835'>3835</a>
<a id='n3836' href='#n3836'>3836</a>
<a id='n3837' href='#n3837'>3837</a>
<a id='n3838' href='#n3838'>3838</a>
<a id='n3839' href='#n3839'>3839</a>
<a id='n3840' href='#n3840'>3840</a>
<a id='n3841' href='#n3841'>3841</a>
<a id='n3842' href='#n3842'>3842</a>
<a id='n3843' href='#n3843'>3843</a>
<a id='n3844' href='#n3844'>3844</a>
<a id='n3845' href='#n3845'>3845</a>
<a id='n3846' href='#n3846'>3846</a>
<a id='n3847' href='#n3847'>3847</a>
<a id='n3848' href='#n3848'>3848</a>
<a id='n3849' href='#n3849'>3849</a>
<a id='n3850' href='#n3850'>3850</a>
<a id='n3851' href='#n3851'>3851</a>
<a id='n3852' href='#n3852'>3852</a>
<a id='n3853' href='#n3853'>3853</a>
<a id='n3854' href='#n3854'>3854</a>
<a id='n3855' href='#n3855'>3855</a>
<a id='n3856' href='#n3856'>3856</a>
<a id='n3857' href='#n3857'>3857</a>
<a id='n3858' href='#n3858'>3858</a>
<a id='n3859' href='#n3859'>3859</a>
<a id='n3860' href='#n3860'>3860</a>
<a id='n3861' href='#n3861'>3861</a>
<a id='n3862' href='#n3862'>3862</a>
<a id='n3863' href='#n3863'>3863</a>
<a id='n3864' href='#n3864'>3864</a>
<a id='n3865' href='#n3865'>3865</a>
<a id='n3866' href='#n3866'>3866</a>
<a id='n3867' href='#n3867'>3867</a>
<a id='n3868' href='#n3868'>3868</a>
<a id='n3869' href='#n3869'>3869</a>
<a id='n3870' href='#n3870'>3870</a>
<a id='n3871' href='#n3871'>3871</a>
<a id='n3872' href='#n3872'>3872</a>
<a id='n3873' href='#n3873'>3873</a>
<a id='n3874' href='#n3874'>3874</a>
<a id='n3875' href='#n3875'>3875</a>
<a id='n3876' href='#n3876'>3876</a>
<a id='n3877' href='#n3877'>3877</a>
<a id='n3878' href='#n3878'>3878</a>
<a id='n3879' href='#n3879'>3879</a>
<a id='n3880' href='#n3880'>3880</a>
<a id='n3881' href='#n3881'>3881</a>
<a id='n3882' href='#n3882'>3882</a>
<a id='n3883' href='#n3883'>3883</a>
<a id='n3884' href='#n3884'>3884</a>
<a id='n3885' href='#n3885'>3885</a>
<a id='n3886' href='#n3886'>3886</a>
<a id='n3887' href='#n3887'>3887</a>
<a id='n3888' href='#n3888'>3888</a>
<a id='n3889' href='#n3889'>3889</a>
<a id='n3890' href='#n3890'>3890</a>
<a id='n3891' href='#n3891'>3891</a>
<a id='n3892' href='#n3892'>3892</a>
<a id='n3893' href='#n3893'>3893</a>
<a id='n3894' href='#n3894'>3894</a>
<a id='n3895' href='#n3895'>3895</a>
<a id='n3896' href='#n3896'>3896</a>
<a id='n3897' href='#n3897'>3897</a>
<a id='n3898' href='#n3898'>3898</a>
<a id='n3899' href='#n3899'>3899</a>
<a id='n3900' href='#n3900'>3900</a>
<a id='n3901' href='#n3901'>3901</a>
<a id='n3902' href='#n3902'>3902</a>
<a id='n3903' href='#n3903'>3903</a>
<a id='n3904' href='#n3904'>3904</a>
<a id='n3905' href='#n3905'>3905</a>
<a id='n3906' href='#n3906'>3906</a>
<a id='n3907' href='#n3907'>3907</a>
<a id='n3908' href='#n3908'>3908</a>
<a id='n3909' href='#n3909'>3909</a>
<a id='n3910' href='#n3910'>3910</a>
<a id='n3911' href='#n3911'>3911</a>
<a id='n3912' href='#n3912'>3912</a>
<a id='n3913' href='#n3913'>3913</a>
<a id='n3914' href='#n3914'>3914</a>
<a id='n3915' href='#n3915'>3915</a>
<a id='n3916' href='#n3916'>3916</a>
<a id='n3917' href='#n3917'>3917</a>
<a id='n3918' href='#n3918'>3918</a>
<a id='n3919' href='#n3919'>3919</a>
<a id='n3920' href='#n3920'>3920</a>
<a id='n3921' href='#n3921'>3921</a>
<a id='n3922' href='#n3922'>3922</a>
<a id='n3923' href='#n3923'>3923</a>
<a id='n3924' href='#n3924'>3924</a>
<a id='n3925' href='#n3925'>3925</a>
<a id='n3926' href='#n3926'>3926</a>
<a id='n3927' href='#n3927'>3927</a>
<a id='n3928' href='#n3928'>3928</a>
<a id='n3929' href='#n3929'>3929</a>
<a id='n3930' href='#n3930'>3930</a>
<a id='n3931' href='#n3931'>3931</a>
<a id='n3932' href='#n3932'>3932</a>
<a id='n3933' href='#n3933'>3933</a>
<a id='n3934' href='#n3934'>3934</a>
<a id='n3935' href='#n3935'>3935</a>
<a id='n3936' href='#n3936'>3936</a>
<a id='n3937' href='#n3937'>3937</a>
<a id='n3938' href='#n3938'>3938</a>
<a id='n3939' href='#n3939'>3939</a>
<a id='n3940' href='#n3940'>3940</a>
<a id='n3941' href='#n3941'>3941</a>
<a id='n3942' href='#n3942'>3942</a>
<a id='n3943' href='#n3943'>3943</a>
<a id='n3944' href='#n3944'>3944</a>
<a id='n3945' href='#n3945'>3945</a>
<a id='n3946' href='#n3946'>3946</a>
<a id='n3947' href='#n3947'>3947</a>
<a id='n3948' href='#n3948'>3948</a>
<a id='n3949' href='#n3949'>3949</a>
<a id='n3950' href='#n3950'>3950</a>
<a id='n3951' href='#n3951'>3951</a>
<a id='n3952' href='#n3952'>3952</a>
<a id='n3953' href='#n3953'>3953</a>
<a id='n3954' href='#n3954'>3954</a>
<a id='n3955' href='#n3955'>3955</a>
<a id='n3956' href='#n3956'>3956</a>
<a id='n3957' href='#n3957'>3957</a>
<a id='n3958' href='#n3958'>3958</a>
<a id='n3959' href='#n3959'>3959</a>
<a id='n3960' href='#n3960'>3960</a>
<a id='n3961' href='#n3961'>3961</a>
<a id='n3962' href='#n3962'>3962</a>
<a id='n3963' href='#n3963'>3963</a>
<a id='n3964' href='#n3964'>3964</a>
<a id='n3965' href='#n3965'>3965</a>
<a id='n3966' href='#n3966'>3966</a>
<a id='n3967' href='#n3967'>3967</a>
<a id='n3968' href='#n3968'>3968</a>
<a id='n3969' href='#n3969'>3969</a>
<a id='n3970' href='#n3970'>3970</a>
<a id='n3971' href='#n3971'>3971</a>
<a id='n3972' href='#n3972'>3972</a>
<a id='n3973' href='#n3973'>3973</a>
<a id='n3974' href='#n3974'>3974</a>
<a id='n3975' href='#n3975'>3975</a>
<a id='n3976' href='#n3976'>3976</a>
<a id='n3977' href='#n3977'>3977</a>
<a id='n3978' href='#n3978'>3978</a>
<a id='n3979' href='#n3979'>3979</a>
<a id='n3980' href='#n3980'>3980</a>
<a id='n3981' href='#n3981'>3981</a>
<a id='n3982' href='#n3982'>3982</a>
<a id='n3983' href='#n3983'>3983</a>
<a id='n3984' href='#n3984'>3984</a>
<a id='n3985' href='#n3985'>3985</a>
<a id='n3986' href='#n3986'>3986</a>
<a id='n3987' href='#n3987'>3987</a>
<a id='n3988' href='#n3988'>3988</a>
<a id='n3989' href='#n3989'>3989</a>
<a id='n3990' href='#n3990'>3990</a>
<a id='n3991' href='#n3991'>3991</a>
<a id='n3992' href='#n3992'>3992</a>
<a id='n3993' href='#n3993'>3993</a>
<a id='n3994' href='#n3994'>3994</a>
<a id='n3995' href='#n3995'>3995</a>
<a id='n3996' href='#n3996'>3996</a>
<a id='n3997' href='#n3997'>3997</a>
<a id='n3998' href='#n3998'>3998</a>
<a id='n3999' href='#n3999'>3999</a>
<a id='n4000' href='#n4000'>4000</a>
<a id='n4001' href='#n4001'>4001</a>
<a id='n4002' href='#n4002'>4002</a>
<a id='n4003' href='#n4003'>4003</a>
<a id='n4004' href='#n4004'>4004</a>
<a id='n4005' href='#n4005'>4005</a>
<a id='n4006' href='#n4006'>4006</a>
<a id='n4007' href='#n4007'>4007</a>
<a id='n4008' href='#n4008'>4008</a>
<a id='n4009' href='#n4009'>4009</a>
<a id='n4010' href='#n4010'>4010</a>
<a id='n4011' href='#n4011'>4011</a>
<a id='n4012' href='#n4012'>4012</a>
<a id='n4013' href='#n4013'>4013</a>
<a id='n4014' href='#n4014'>4014</a>
<a id='n4015' href='#n4015'>4015</a>
<a id='n4016' href='#n4016'>4016</a>
<a id='n4017' href='#n4017'>4017</a>
<a id='n4018' href='#n4018'>4018</a>
<a id='n4019' href='#n4019'>4019</a>
<a id='n4020' href='#n4020'>4020</a>
<a id='n4021' href='#n4021'>4021</a>
<a id='n4022' href='#n4022'>4022</a>
<a id='n4023' href='#n4023'>4023</a>
<a id='n4024' href='#n4024'>4024</a>
<a id='n4025' href='#n4025'>4025</a>
<a id='n4026' href='#n4026'>4026</a>
<a id='n4027' href='#n4027'>4027</a>
<a id='n4028' href='#n4028'>4028</a>
<a id='n4029' href='#n4029'>4029</a>
<a id='n4030' href='#n4030'>4030</a>
<a id='n4031' href='#n4031'>4031</a>
<a id='n4032' href='#n4032'>4032</a>
<a id='n4033' href='#n4033'>4033</a>
<a id='n4034' href='#n4034'>4034</a>
<a id='n4035' href='#n4035'>4035</a>
<a id='n4036' href='#n4036'>4036</a>
<a id='n4037' href='#n4037'>4037</a>
<a id='n4038' href='#n4038'>4038</a>
<a id='n4039' href='#n4039'>4039</a>
<a id='n4040' href='#n4040'>4040</a>
<a id='n4041' href='#n4041'>4041</a>
<a id='n4042' href='#n4042'>4042</a>
<a id='n4043' href='#n4043'>4043</a>
<a id='n4044' href='#n4044'>4044</a>
<a id='n4045' href='#n4045'>4045</a>
<a id='n4046' href='#n4046'>4046</a>
<a id='n4047' href='#n4047'>4047</a>
<a id='n4048' href='#n4048'>4048</a>
<a id='n4049' href='#n4049'>4049</a>
<a id='n4050' href='#n4050'>4050</a>
<a id='n4051' href='#n4051'>4051</a>
<a id='n4052' href='#n4052'>4052</a>
<a id='n4053' href='#n4053'>4053</a>
<a id='n4054' href='#n4054'>4054</a>
<a id='n4055' href='#n4055'>4055</a>
<a id='n4056' href='#n4056'>4056</a>
<a id='n4057' href='#n4057'>4057</a>
<a id='n4058' href='#n4058'>4058</a>
<a id='n4059' href='#n4059'>4059</a>
<a id='n4060' href='#n4060'>4060</a>
<a id='n4061' href='#n4061'>4061</a>
<a id='n4062' href='#n4062'>4062</a>
<a id='n4063' href='#n4063'>4063</a>
<a id='n4064' href='#n4064'>4064</a>
<a id='n4065' href='#n4065'>4065</a>
<a id='n4066' href='#n4066'>4066</a>
<a id='n4067' href='#n4067'>4067</a>
<a id='n4068' href='#n4068'>4068</a>
<a id='n4069' href='#n4069'>4069</a>
<a id='n4070' href='#n4070'>4070</a>
<a id='n4071' href='#n4071'>4071</a>
<a id='n4072' href='#n4072'>4072</a>
<a id='n4073' href='#n4073'>4073</a>
<a id='n4074' href='#n4074'>4074</a>
<a id='n4075' href='#n4075'>4075</a>
<a id='n4076' href='#n4076'>4076</a>
<a id='n4077' href='#n4077'>4077</a>
<a id='n4078' href='#n4078'>4078</a>
<a id='n4079' href='#n4079'>4079</a>
<a id='n4080' href='#n4080'>4080</a>
<a id='n4081' href='#n4081'>4081</a>
<a id='n4082' href='#n4082'>4082</a>
<a id='n4083' href='#n4083'>4083</a>
<a id='n4084' href='#n4084'>4084</a>
<a id='n4085' href='#n4085'>4085</a>
<a id='n4086' href='#n4086'>4086</a>
<a id='n4087' href='#n4087'>4087</a>
<a id='n4088' href='#n4088'>4088</a>
<a id='n4089' href='#n4089'>4089</a>
<a id='n4090' href='#n4090'>4090</a>
<a id='n4091' href='#n4091'>4091</a>
<a id='n4092' href='#n4092'>4092</a>
<a id='n4093' href='#n4093'>4093</a>
<a id='n4094' href='#n4094'>4094</a>
<a id='n4095' href='#n4095'>4095</a>
<a id='n4096' href='#n4096'>4096</a>
<a id='n4097' href='#n4097'>4097</a>
<a id='n4098' href='#n4098'>4098</a>
<a id='n4099' href='#n4099'>4099</a>
<a id='n4100' href='#n4100'>4100</a>
<a id='n4101' href='#n4101'>4101</a>
<a id='n4102' href='#n4102'>4102</a>
<a id='n4103' href='#n4103'>4103</a>
<a id='n4104' href='#n4104'>4104</a>
<a id='n4105' href='#n4105'>4105</a>
<a id='n4106' href='#n4106'>4106</a>
<a id='n4107' href='#n4107'>4107</a>
<a id='n4108' href='#n4108'>4108</a>
<a id='n4109' href='#n4109'>4109</a>
<a id='n4110' href='#n4110'>4110</a>
<a id='n4111' href='#n4111'>4111</a>
<a id='n4112' href='#n4112'>4112</a>
<a id='n4113' href='#n4113'>4113</a>
<a id='n4114' href='#n4114'>4114</a>
<a id='n4115' href='#n4115'>4115</a>
<a id='n4116' href='#n4116'>4116</a>
<a id='n4117' href='#n4117'>4117</a>
<a id='n4118' href='#n4118'>4118</a>
<a id='n4119' href='#n4119'>4119</a>
<a id='n4120' href='#n4120'>4120</a>
<a id='n4121' href='#n4121'>4121</a>
<a id='n4122' href='#n4122'>4122</a>
<a id='n4123' href='#n4123'>4123</a>
<a id='n4124' href='#n4124'>4124</a>
<a id='n4125' href='#n4125'>4125</a>
<a id='n4126' href='#n4126'>4126</a>
<a id='n4127' href='#n4127'>4127</a>
<a id='n4128' href='#n4128'>4128</a>
<a id='n4129' href='#n4129'>4129</a>
<a id='n4130' href='#n4130'>4130</a>
<a id='n4131' href='#n4131'>4131</a>
<a id='n4132' href='#n4132'>4132</a>
<a id='n4133' href='#n4133'>4133</a>
<a id='n4134' href='#n4134'>4134</a>
<a id='n4135' href='#n4135'>4135</a>
<a id='n4136' href='#n4136'>4136</a>
<a id='n4137' href='#n4137'>4137</a>
<a id='n4138' href='#n4138'>4138</a>
<a id='n4139' href='#n4139'>4139</a>
<a id='n4140' href='#n4140'>4140</a>
<a id='n4141' href='#n4141'>4141</a>
<a id='n4142' href='#n4142'>4142</a>
<a id='n4143' href='#n4143'>4143</a>
<a id='n4144' href='#n4144'>4144</a>
<a id='n4145' href='#n4145'>4145</a>
<a id='n4146' href='#n4146'>4146</a>
<a id='n4147' href='#n4147'>4147</a>
<a id='n4148' href='#n4148'>4148</a>
<a id='n4149' href='#n4149'>4149</a>
<a id='n4150' href='#n4150'>4150</a>
<a id='n4151' href='#n4151'>4151</a>
<a id='n4152' href='#n4152'>4152</a>
<a id='n4153' href='#n4153'>4153</a>
<a id='n4154' href='#n4154'>4154</a>
<a id='n4155' href='#n4155'>4155</a>
<a id='n4156' href='#n4156'>4156</a>
<a id='n4157' href='#n4157'>4157</a>
<a id='n4158' href='#n4158'>4158</a>
<a id='n4159' href='#n4159'>4159</a>
<a id='n4160' href='#n4160'>4160</a>
<a id='n4161' href='#n4161'>4161</a>
<a id='n4162' href='#n4162'>4162</a>
<a id='n4163' href='#n4163'>4163</a>
<a id='n4164' href='#n4164'>4164</a>
<a id='n4165' href='#n4165'>4165</a>
<a id='n4166' href='#n4166'>4166</a>
<a id='n4167' href='#n4167'>4167</a>
<a id='n4168' href='#n4168'>4168</a>
<a id='n4169' href='#n4169'>4169</a>
<a id='n4170' href='#n4170'>4170</a>
<a id='n4171' href='#n4171'>4171</a>
<a id='n4172' href='#n4172'>4172</a>
<a id='n4173' href='#n4173'>4173</a>
<a id='n4174' href='#n4174'>4174</a>
<a id='n4175' href='#n4175'>4175</a>
<a id='n4176' href='#n4176'>4176</a>
<a id='n4177' href='#n4177'>4177</a>
<a id='n4178' href='#n4178'>4178</a>
<a id='n4179' href='#n4179'>4179</a>
<a id='n4180' href='#n4180'>4180</a>
<a id='n4181' href='#n4181'>4181</a>
<a id='n4182' href='#n4182'>4182</a>
<a id='n4183' href='#n4183'>4183</a>
<a id='n4184' href='#n4184'>4184</a>
<a id='n4185' href='#n4185'>4185</a>
<a id='n4186' href='#n4186'>4186</a>
<a id='n4187' href='#n4187'>4187</a>
<a id='n4188' href='#n4188'>4188</a>
<a id='n4189' href='#n4189'>4189</a>
<a id='n4190' href='#n4190'>4190</a>
<a id='n4191' href='#n4191'>4191</a>
<a id='n4192' href='#n4192'>4192</a>
<a id='n4193' href='#n4193'>4193</a>
<a id='n4194' href='#n4194'>4194</a>
<a id='n4195' href='#n4195'>4195</a>
<a id='n4196' href='#n4196'>4196</a>
<a id='n4197' href='#n4197'>4197</a>
<a id='n4198' href='#n4198'>4198</a>
<a id='n4199' href='#n4199'>4199</a>
<a id='n4200' href='#n4200'>4200</a>
<a id='n4201' href='#n4201'>4201</a>
<a id='n4202' href='#n4202'>4202</a>
<a id='n4203' href='#n4203'>4203</a>
<a id='n4204' href='#n4204'>4204</a>
<a id='n4205' href='#n4205'>4205</a>
<a id='n4206' href='#n4206'>4206</a>
<a id='n4207' href='#n4207'>4207</a>
<a id='n4208' href='#n4208'>4208</a>
<a id='n4209' href='#n4209'>4209</a>
<a id='n4210' href='#n4210'>4210</a>
<a id='n4211' href='#n4211'>4211</a>
<a id='n4212' href='#n4212'>4212</a>
<a id='n4213' href='#n4213'>4213</a>
<a id='n4214' href='#n4214'>4214</a>
<a id='n4215' href='#n4215'>4215</a>
<a id='n4216' href='#n4216'>4216</a>
<a id='n4217' href='#n4217'>4217</a>
<a id='n4218' href='#n4218'>4218</a>
<a id='n4219' href='#n4219'>4219</a>
<a id='n4220' href='#n4220'>4220</a>
<a id='n4221' href='#n4221'>4221</a>
<a id='n4222' href='#n4222'>4222</a>
<a id='n4223' href='#n4223'>4223</a>
<a id='n4224' href='#n4224'>4224</a>
<a id='n4225' href='#n4225'>4225</a>
<a id='n4226' href='#n4226'>4226</a>
<a id='n4227' href='#n4227'>4227</a>
<a id='n4228' href='#n4228'>4228</a>
<a id='n4229' href='#n4229'>4229</a>
<a id='n4230' href='#n4230'>4230</a>
<a id='n4231' href='#n4231'>4231</a>
<a id='n4232' href='#n4232'>4232</a>
<a id='n4233' href='#n4233'>4233</a>
<a id='n4234' href='#n4234'>4234</a>
<a id='n4235' href='#n4235'>4235</a>
<a id='n4236' href='#n4236'>4236</a>
<a id='n4237' href='#n4237'>4237</a>
<a id='n4238' href='#n4238'>4238</a>
<a id='n4239' href='#n4239'>4239</a>
<a id='n4240' href='#n4240'>4240</a>
<a id='n4241' href='#n4241'>4241</a>
<a id='n4242' href='#n4242'>4242</a>
<a id='n4243' href='#n4243'>4243</a>
<a id='n4244' href='#n4244'>4244</a>
<a id='n4245' href='#n4245'>4245</a>
<a id='n4246' href='#n4246'>4246</a>
<a id='n4247' href='#n4247'>4247</a>
<a id='n4248' href='#n4248'>4248</a>
<a id='n4249' href='#n4249'>4249</a>
<a id='n4250' href='#n4250'>4250</a>
<a id='n4251' href='#n4251'>4251</a>
<a id='n4252' href='#n4252'>4252</a>
<a id='n4253' href='#n4253'>4253</a>
<a id='n4254' href='#n4254'>4254</a>
<a id='n4255' href='#n4255'>4255</a>
<a id='n4256' href='#n4256'>4256</a>
<a id='n4257' href='#n4257'>4257</a>
<a id='n4258' href='#n4258'>4258</a>
<a id='n4259' href='#n4259'>4259</a>
<a id='n4260' href='#n4260'>4260</a>
<a id='n4261' href='#n4261'>4261</a>
<a id='n4262' href='#n4262'>4262</a>
<a id='n4263' href='#n4263'>4263</a>
<a id='n4264' href='#n4264'>4264</a>
<a id='n4265' href='#n4265'>4265</a>
<a id='n4266' href='#n4266'>4266</a>
<a id='n4267' href='#n4267'>4267</a>
<a id='n4268' href='#n4268'>4268</a>
<a id='n4269' href='#n4269'>4269</a>
<a id='n4270' href='#n4270'>4270</a>
<a id='n4271' href='#n4271'>4271</a>
<a id='n4272' href='#n4272'>4272</a>
<a id='n4273' href='#n4273'>4273</a>
<a id='n4274' href='#n4274'>4274</a>
<a id='n4275' href='#n4275'>4275</a>
<a id='n4276' href='#n4276'>4276</a>
<a id='n4277' href='#n4277'>4277</a>
<a id='n4278' href='#n4278'>4278</a>
<a id='n4279' href='#n4279'>4279</a>
<a id='n4280' href='#n4280'>4280</a>
<a id='n4281' href='#n4281'>4281</a>
<a id='n4282' href='#n4282'>4282</a>
<a id='n4283' href='#n4283'>4283</a>
<a id='n4284' href='#n4284'>4284</a>
<a id='n4285' href='#n4285'>4285</a>
<a id='n4286' href='#n4286'>4286</a>
<a id='n4287' href='#n4287'>4287</a>
<a id='n4288' href='#n4288'>4288</a>
<a id='n4289' href='#n4289'>4289</a>
<a id='n4290' href='#n4290'>4290</a>
<a id='n4291' href='#n4291'>4291</a>
<a id='n4292' href='#n4292'>4292</a>
<a id='n4293' href='#n4293'>4293</a>
<a id='n4294' href='#n4294'>4294</a>
<a id='n4295' href='#n4295'>4295</a>
<a id='n4296' href='#n4296'>4296</a>
<a id='n4297' href='#n4297'>4297</a>
<a id='n4298' href='#n4298'>4298</a>
<a id='n4299' href='#n4299'>4299</a>
<a id='n4300' href='#n4300'>4300</a>
<a id='n4301' href='#n4301'>4301</a>
<a id='n4302' href='#n4302'>4302</a>
<a id='n4303' href='#n4303'>4303</a>
<a id='n4304' href='#n4304'>4304</a>
<a id='n4305' href='#n4305'>4305</a>
<a id='n4306' href='#n4306'>4306</a>
<a id='n4307' href='#n4307'>4307</a>
<a id='n4308' href='#n4308'>4308</a>
<a id='n4309' href='#n4309'>4309</a>
<a id='n4310' href='#n4310'>4310</a>
<a id='n4311' href='#n4311'>4311</a>
<a id='n4312' href='#n4312'>4312</a>
<a id='n4313' href='#n4313'>4313</a>
<a id='n4314' href='#n4314'>4314</a>
<a id='n4315' href='#n4315'>4315</a>
<a id='n4316' href='#n4316'>4316</a>
<a id='n4317' href='#n4317'>4317</a>
<a id='n4318' href='#n4318'>4318</a>
<a id='n4319' href='#n4319'>4319</a>
<a id='n4320' href='#n4320'>4320</a>
<a id='n4321' href='#n4321'>4321</a>
<a id='n4322' href='#n4322'>4322</a>
<a id='n4323' href='#n4323'>4323</a>
<a id='n4324' href='#n4324'>4324</a>
<a id='n4325' href='#n4325'>4325</a>
<a id='n4326' href='#n4326'>4326</a>
<a id='n4327' href='#n4327'>4327</a>
<a id='n4328' href='#n4328'>4328</a>
<a id='n4329' href='#n4329'>4329</a>
<a id='n4330' href='#n4330'>4330</a>
<a id='n4331' href='#n4331'>4331</a>
<a id='n4332' href='#n4332'>4332</a>
<a id='n4333' href='#n4333'>4333</a>
<a id='n4334' href='#n4334'>4334</a>
<a id='n4335' href='#n4335'>4335</a>
<a id='n4336' href='#n4336'>4336</a>
<a id='n4337' href='#n4337'>4337</a>
<a id='n4338' href='#n4338'>4338</a>
<a id='n4339' href='#n4339'>4339</a>
<a id='n4340' href='#n4340'>4340</a>
<a id='n4341' href='#n4341'>4341</a>
<a id='n4342' href='#n4342'>4342</a>
<a id='n4343' href='#n4343'>4343</a>
<a id='n4344' href='#n4344'>4344</a>
<a id='n4345' href='#n4345'>4345</a>
<a id='n4346' href='#n4346'>4346</a>
<a id='n4347' href='#n4347'>4347</a>
<a id='n4348' href='#n4348'>4348</a>
<a id='n4349' href='#n4349'>4349</a>
<a id='n4350' href='#n4350'>4350</a>
<a id='n4351' href='#n4351'>4351</a>
<a id='n4352' href='#n4352'>4352</a>
<a id='n4353' href='#n4353'>4353</a>
<a id='n4354' href='#n4354'>4354</a>
<a id='n4355' href='#n4355'>4355</a>
<a id='n4356' href='#n4356'>4356</a>
<a id='n4357' href='#n4357'>4357</a>
<a id='n4358' href='#n4358'>4358</a>
<a id='n4359' href='#n4359'>4359</a>
<a id='n4360' href='#n4360'>4360</a>
<a id='n4361' href='#n4361'>4361</a>
<a id='n4362' href='#n4362'>4362</a>
<a id='n4363' href='#n4363'>4363</a>
<a id='n4364' href='#n4364'>4364</a>
<a id='n4365' href='#n4365'>4365</a>
<a id='n4366' href='#n4366'>4366</a>
<a id='n4367' href='#n4367'>4367</a>
<a id='n4368' href='#n4368'>4368</a>
<a id='n4369' href='#n4369'>4369</a>
<a id='n4370' href='#n4370'>4370</a>
<a id='n4371' href='#n4371'>4371</a>
<a id='n4372' href='#n4372'>4372</a>
<a id='n4373' href='#n4373'>4373</a>
<a id='n4374' href='#n4374'>4374</a>
<a id='n4375' href='#n4375'>4375</a>
<a id='n4376' href='#n4376'>4376</a>
<a id='n4377' href='#n4377'>4377</a>
<a id='n4378' href='#n4378'>4378</a>
<a id='n4379' href='#n4379'>4379</a>
<a id='n4380' href='#n4380'>4380</a>
<a id='n4381' href='#n4381'>4381</a>
<a id='n4382' href='#n4382'>4382</a>
<a id='n4383' href='#n4383'>4383</a>
<a id='n4384' href='#n4384'>4384</a>
<a id='n4385' href='#n4385'>4385</a>
<a id='n4386' href='#n4386'>4386</a>
<a id='n4387' href='#n4387'>4387</a>
<a id='n4388' href='#n4388'>4388</a>
<a id='n4389' href='#n4389'>4389</a>
<a id='n4390' href='#n4390'>4390</a>
<a id='n4391' href='#n4391'>4391</a>
<a id='n4392' href='#n4392'>4392</a>
<a id='n4393' href='#n4393'>4393</a>
<a id='n4394' href='#n4394'>4394</a>
<a id='n4395' href='#n4395'>4395</a>
<a id='n4396' href='#n4396'>4396</a>
<a id='n4397' href='#n4397'>4397</a>
<a id='n4398' href='#n4398'>4398</a>
<a id='n4399' href='#n4399'>4399</a>
<a id='n4400' href='#n4400'>4400</a>
<a id='n4401' href='#n4401'>4401</a>
<a id='n4402' href='#n4402'>4402</a>
<a id='n4403' href='#n4403'>4403</a>
<a id='n4404' href='#n4404'>4404</a>
<a id='n4405' href='#n4405'>4405</a>
<a id='n4406' href='#n4406'>4406</a>
<a id='n4407' href='#n4407'>4407</a>
<a id='n4408' href='#n4408'>4408</a>
<a id='n4409' href='#n4409'>4409</a>
<a id='n4410' href='#n4410'>4410</a>
<a id='n4411' href='#n4411'>4411</a>
<a id='n4412' href='#n4412'>4412</a>
<a id='n4413' href='#n4413'>4413</a>
<a id='n4414' href='#n4414'>4414</a>
<a id='n4415' href='#n4415'>4415</a>
<a id='n4416' href='#n4416'>4416</a>
<a id='n4417' href='#n4417'>4417</a>
<a id='n4418' href='#n4418'>4418</a>
<a id='n4419' href='#n4419'>4419</a>
<a id='n4420' href='#n4420'>4420</a>
<a id='n4421' href='#n4421'>4421</a>
<a id='n4422' href='#n4422'>4422</a>
<a id='n4423' href='#n4423'>4423</a>
<a id='n4424' href='#n4424'>4424</a>
<a id='n4425' href='#n4425'>4425</a>
<a id='n4426' href='#n4426'>4426</a>
<a id='n4427' href='#n4427'>4427</a>
<a id='n4428' href='#n4428'>4428</a>
<a id='n4429' href='#n4429'>4429</a>
<a id='n4430' href='#n4430'>4430</a>
<a id='n4431' href='#n4431'>4431</a>
<a id='n4432' href='#n4432'>4432</a>
<a id='n4433' href='#n4433'>4433</a>
<a id='n4434' href='#n4434'>4434</a>
<a id='n4435' href='#n4435'>4435</a>
<a id='n4436' href='#n4436'>4436</a>
<a id='n4437' href='#n4437'>4437</a>
<a id='n4438' href='#n4438'>4438</a>
<a id='n4439' href='#n4439'>4439</a>
<a id='n4440' href='#n4440'>4440</a>
<a id='n4441' href='#n4441'>4441</a>
<a id='n4442' href='#n4442'>4442</a>
<a id='n4443' href='#n4443'>4443</a>
<a id='n4444' href='#n4444'>4444</a>
<a id='n4445' href='#n4445'>4445</a>
<a id='n4446' href='#n4446'>4446</a>
<a id='n4447' href='#n4447'>4447</a>
<a id='n4448' href='#n4448'>4448</a>
<a id='n4449' href='#n4449'>4449</a>
<a id='n4450' href='#n4450'>4450</a>
<a id='n4451' href='#n4451'>4451</a>
<a id='n4452' href='#n4452'>4452</a>
<a id='n4453' href='#n4453'>4453</a>
<a id='n4454' href='#n4454'>4454</a>
<a id='n4455' href='#n4455'>4455</a>
<a id='n4456' href='#n4456'>4456</a>
<a id='n4457' href='#n4457'>4457</a>
<a id='n4458' href='#n4458'>4458</a>
<a id='n4459' href='#n4459'>4459</a>
<a id='n4460' href='#n4460'>4460</a>
<a id='n4461' href='#n4461'>4461</a>
<a id='n4462' href='#n4462'>4462</a>
<a id='n4463' href='#n4463'>4463</a>
<a id='n4464' href='#n4464'>4464</a>
<a id='n4465' href='#n4465'>4465</a>
<a id='n4466' href='#n4466'>4466</a>
<a id='n4467' href='#n4467'>4467</a>
<a id='n4468' href='#n4468'>4468</a>
<a id='n4469' href='#n4469'>4469</a>
<a id='n4470' href='#n4470'>4470</a>
<a id='n4471' href='#n4471'>4471</a>
<a id='n4472' href='#n4472'>4472</a>
<a id='n4473' href='#n4473'>4473</a>
<a id='n4474' href='#n4474'>4474</a>
<a id='n4475' href='#n4475'>4475</a>
<a id='n4476' href='#n4476'>4476</a>
<a id='n4477' href='#n4477'>4477</a>
<a id='n4478' href='#n4478'>4478</a>
<a id='n4479' href='#n4479'>4479</a>
<a id='n4480' href='#n4480'>4480</a>
<a id='n4481' href='#n4481'>4481</a>
<a id='n4482' href='#n4482'>4482</a>
<a id='n4483' href='#n4483'>4483</a>
<a id='n4484' href='#n4484'>4484</a>
<a id='n4485' href='#n4485'>4485</a>
<a id='n4486' href='#n4486'>4486</a>
<a id='n4487' href='#n4487'>4487</a>
<a id='n4488' href='#n4488'>4488</a>
<a id='n4489' href='#n4489'>4489</a>
<a id='n4490' href='#n4490'>4490</a>
<a id='n4491' href='#n4491'>4491</a>
<a id='n4492' href='#n4492'>4492</a>
<a id='n4493' href='#n4493'>4493</a>
<a id='n4494' href='#n4494'>4494</a>
<a id='n4495' href='#n4495'>4495</a>
<a id='n4496' href='#n4496'>4496</a>
<a id='n4497' href='#n4497'>4497</a>
<a id='n4498' href='#n4498'>4498</a>
<a id='n4499' href='#n4499'>4499</a>
<a id='n4500' href='#n4500'>4500</a>
<a id='n4501' href='#n4501'>4501</a>
<a id='n4502' href='#n4502'>4502</a>
<a id='n4503' href='#n4503'>4503</a>
<a id='n4504' href='#n4504'>4504</a>
<a id='n4505' href='#n4505'>4505</a>
<a id='n4506' href='#n4506'>4506</a>
<a id='n4507' href='#n4507'>4507</a>
<a id='n4508' href='#n4508'>4508</a>
<a id='n4509' href='#n4509'>4509</a>
<a id='n4510' href='#n4510'>4510</a>
<a id='n4511' href='#n4511'>4511</a>
<a id='n4512' href='#n4512'>4512</a>
<a id='n4513' href='#n4513'>4513</a>
<a id='n4514' href='#n4514'>4514</a>
<a id='n4515' href='#n4515'>4515</a>
<a id='n4516' href='#n4516'>4516</a>
<a id='n4517' href='#n4517'>4517</a>
<a id='n4518' href='#n4518'>4518</a>
<a id='n4519' href='#n4519'>4519</a>
<a id='n4520' href='#n4520'>4520</a>
<a id='n4521' href='#n4521'>4521</a>
<a id='n4522' href='#n4522'>4522</a>
<a id='n4523' href='#n4523'>4523</a>
<a id='n4524' href='#n4524'>4524</a>
<a id='n4525' href='#n4525'>4525</a>
<a id='n4526' href='#n4526'>4526</a>
<a id='n4527' href='#n4527'>4527</a>
<a id='n4528' href='#n4528'>4528</a>
<a id='n4529' href='#n4529'>4529</a>
<a id='n4530' href='#n4530'>4530</a>
<a id='n4531' href='#n4531'>4531</a>
<a id='n4532' href='#n4532'>4532</a>
<a id='n4533' href='#n4533'>4533</a>
<a id='n4534' href='#n4534'>4534</a>
<a id='n4535' href='#n4535'>4535</a>
<a id='n4536' href='#n4536'>4536</a>
<a id='n4537' href='#n4537'>4537</a>
<a id='n4538' href='#n4538'>4538</a>
<a id='n4539' href='#n4539'>4539</a>
<a id='n4540' href='#n4540'>4540</a>
<a id='n4541' href='#n4541'>4541</a>
<a id='n4542' href='#n4542'>4542</a>
<a id='n4543' href='#n4543'>4543</a>
<a id='n4544' href='#n4544'>4544</a>
<a id='n4545' href='#n4545'>4545</a>
<a id='n4546' href='#n4546'>4546</a>
<a id='n4547' href='#n4547'>4547</a>
<a id='n4548' href='#n4548'>4548</a>
<a id='n4549' href='#n4549'>4549</a>
<a id='n4550' href='#n4550'>4550</a>
<a id='n4551' href='#n4551'>4551</a>
<a id='n4552' href='#n4552'>4552</a>
<a id='n4553' href='#n4553'>4553</a>
<a id='n4554' href='#n4554'>4554</a>
<a id='n4555' href='#n4555'>4555</a>
<a id='n4556' href='#n4556'>4556</a>
<a id='n4557' href='#n4557'>4557</a>
<a id='n4558' href='#n4558'>4558</a>
<a id='n4559' href='#n4559'>4559</a>
<a id='n4560' href='#n4560'>4560</a>
<a id='n4561' href='#n4561'>4561</a>
<a id='n4562' href='#n4562'>4562</a>
<a id='n4563' href='#n4563'>4563</a>
<a id='n4564' href='#n4564'>4564</a>
<a id='n4565' href='#n4565'>4565</a>
<a id='n4566' href='#n4566'>4566</a>
<a id='n4567' href='#n4567'>4567</a>
<a id='n4568' href='#n4568'>4568</a>
<a id='n4569' href='#n4569'>4569</a>
<a id='n4570' href='#n4570'>4570</a>
<a id='n4571' href='#n4571'>4571</a>
<a id='n4572' href='#n4572'>4572</a>
<a id='n4573' href='#n4573'>4573</a>
<a id='n4574' href='#n4574'>4574</a>
<a id='n4575' href='#n4575'>4575</a>
<a id='n4576' href='#n4576'>4576</a>
<a id='n4577' href='#n4577'>4577</a>
<a id='n4578' href='#n4578'>4578</a>
<a id='n4579' href='#n4579'>4579</a>
<a id='n4580' href='#n4580'>4580</a>
<a id='n4581' href='#n4581'>4581</a>
<a id='n4582' href='#n4582'>4582</a>
<a id='n4583' href='#n4583'>4583</a>
<a id='n4584' href='#n4584'>4584</a>
<a id='n4585' href='#n4585'>4585</a>
<a id='n4586' href='#n4586'>4586</a>
<a id='n4587' href='#n4587'>4587</a>
<a id='n4588' href='#n4588'>4588</a>
<a id='n4589' href='#n4589'>4589</a>
<a id='n4590' href='#n4590'>4590</a>
<a id='n4591' href='#n4591'>4591</a>
<a id='n4592' href='#n4592'>4592</a>
<a id='n4593' href='#n4593'>4593</a>
<a id='n4594' href='#n4594'>4594</a>
<a id='n4595' href='#n4595'>4595</a>
<a id='n4596' href='#n4596'>4596</a>
<a id='n4597' href='#n4597'>4597</a>
<a id='n4598' href='#n4598'>4598</a>
<a id='n4599' href='#n4599'>4599</a>
<a id='n4600' href='#n4600'>4600</a>
<a id='n4601' href='#n4601'>4601</a>
<a id='n4602' href='#n4602'>4602</a>
<a id='n4603' href='#n4603'>4603</a>
<a id='n4604' href='#n4604'>4604</a>
<a id='n4605' href='#n4605'>4605</a>
<a id='n4606' href='#n4606'>4606</a>
<a id='n4607' href='#n4607'>4607</a>
<a id='n4608' href='#n4608'>4608</a>
<a id='n4609' href='#n4609'>4609</a>
<a id='n4610' href='#n4610'>4610</a>
<a id='n4611' href='#n4611'>4611</a>
<a id='n4612' href='#n4612'>4612</a>
<a id='n4613' href='#n4613'>4613</a>
<a id='n4614' href='#n4614'>4614</a>
<a id='n4615' href='#n4615'>4615</a>
<a id='n4616' href='#n4616'>4616</a>
<a id='n4617' href='#n4617'>4617</a>
<a id='n4618' href='#n4618'>4618</a>
<a id='n4619' href='#n4619'>4619</a>
<a id='n4620' href='#n4620'>4620</a>
<a id='n4621' href='#n4621'>4621</a>
<a id='n4622' href='#n4622'>4622</a>
<a id='n4623' href='#n4623'>4623</a>
<a id='n4624' href='#n4624'>4624</a>
<a id='n4625' href='#n4625'>4625</a>
<a id='n4626' href='#n4626'>4626</a>
<a id='n4627' href='#n4627'>4627</a>
<a id='n4628' href='#n4628'>4628</a>
<a id='n4629' href='#n4629'>4629</a>
<a id='n4630' href='#n4630'>4630</a>
<a id='n4631' href='#n4631'>4631</a>
<a id='n4632' href='#n4632'>4632</a>
<a id='n4633' href='#n4633'>4633</a>
<a id='n4634' href='#n4634'>4634</a>
<a id='n4635' href='#n4635'>4635</a>
<a id='n4636' href='#n4636'>4636</a>
<a id='n4637' href='#n4637'>4637</a>
<a id='n4638' href='#n4638'>4638</a>
<a id='n4639' href='#n4639'>4639</a>
<a id='n4640' href='#n4640'>4640</a>
<a id='n4641' href='#n4641'>4641</a>
<a id='n4642' href='#n4642'>4642</a>
<a id='n4643' href='#n4643'>4643</a>
<a id='n4644' href='#n4644'>4644</a>
<a id='n4645' href='#n4645'>4645</a>
<a id='n4646' href='#n4646'>4646</a>
<a id='n4647' href='#n4647'>4647</a>
<a id='n4648' href='#n4648'>4648</a>
<a id='n4649' href='#n4649'>4649</a>
<a id='n4650' href='#n4650'>4650</a>
<a id='n4651' href='#n4651'>4651</a>
<a id='n4652' href='#n4652'>4652</a>
<a id='n4653' href='#n4653'>4653</a>
<a id='n4654' href='#n4654'>4654</a>
<a id='n4655' href='#n4655'>4655</a>
<a id='n4656' href='#n4656'>4656</a>
<a id='n4657' href='#n4657'>4657</a>
<a id='n4658' href='#n4658'>4658</a>
<a id='n4659' href='#n4659'>4659</a>
<a id='n4660' href='#n4660'>4660</a>
<a id='n4661' href='#n4661'>4661</a>
<a id='n4662' href='#n4662'>4662</a>
<a id='n4663' href='#n4663'>4663</a>
<a id='n4664' href='#n4664'>4664</a>
<a id='n4665' href='#n4665'>4665</a>
<a id='n4666' href='#n4666'>4666</a>
<a id='n4667' href='#n4667'>4667</a>
<a id='n4668' href='#n4668'>4668</a>
<a id='n4669' href='#n4669'>4669</a>
<a id='n4670' href='#n4670'>4670</a>
<a id='n4671' href='#n4671'>4671</a>
<a id='n4672' href='#n4672'>4672</a>
<a id='n4673' href='#n4673'>4673</a>
<a id='n4674' href='#n4674'>4674</a>
<a id='n4675' href='#n4675'>4675</a>
<a id='n4676' href='#n4676'>4676</a>
<a id='n4677' href='#n4677'>4677</a>
<a id='n4678' href='#n4678'>4678</a>
<a id='n4679' href='#n4679'>4679</a>
<a id='n4680' href='#n4680'>4680</a>
<a id='n4681' href='#n4681'>4681</a>
<a id='n4682' href='#n4682'>4682</a>
<a id='n4683' href='#n4683'>4683</a>
<a id='n4684' href='#n4684'>4684</a>
<a id='n4685' href='#n4685'>4685</a>
<a id='n4686' href='#n4686'>4686</a>
<a id='n4687' href='#n4687'>4687</a>
<a id='n4688' href='#n4688'>4688</a>
<a id='n4689' href='#n4689'>4689</a>
<a id='n4690' href='#n4690'>4690</a>
<a id='n4691' href='#n4691'>4691</a>
<a id='n4692' href='#n4692'>4692</a>
<a id='n4693' href='#n4693'>4693</a>
<a id='n4694' href='#n4694'>4694</a>
<a id='n4695' href='#n4695'>4695</a>
<a id='n4696' href='#n4696'>4696</a>
<a id='n4697' href='#n4697'>4697</a>
<a id='n4698' href='#n4698'>4698</a>
<a id='n4699' href='#n4699'>4699</a>
<a id='n4700' href='#n4700'>4700</a>
<a id='n4701' href='#n4701'>4701</a>
<a id='n4702' href='#n4702'>4702</a>
<a id='n4703' href='#n4703'>4703</a>
<a id='n4704' href='#n4704'>4704</a>
<a id='n4705' href='#n4705'>4705</a>
<a id='n4706' href='#n4706'>4706</a>
<a id='n4707' href='#n4707'>4707</a>
<a id='n4708' href='#n4708'>4708</a>
<a id='n4709' href='#n4709'>4709</a>
<a id='n4710' href='#n4710'>4710</a>
<a id='n4711' href='#n4711'>4711</a>
<a id='n4712' href='#n4712'>4712</a>
<a id='n4713' href='#n4713'>4713</a>
<a id='n4714' href='#n4714'>4714</a>
<a id='n4715' href='#n4715'>4715</a>
<a id='n4716' href='#n4716'>4716</a>
<a id='n4717' href='#n4717'>4717</a>
<a id='n4718' href='#n4718'>4718</a>
<a id='n4719' href='#n4719'>4719</a>
<a id='n4720' href='#n4720'>4720</a>
<a id='n4721' href='#n4721'>4721</a>
<a id='n4722' href='#n4722'>4722</a>
<a id='n4723' href='#n4723'>4723</a>
<a id='n4724' href='#n4724'>4724</a>
<a id='n4725' href='#n4725'>4725</a>
<a id='n4726' href='#n4726'>4726</a>
<a id='n4727' href='#n4727'>4727</a>
<a id='n4728' href='#n4728'>4728</a>
<a id='n4729' href='#n4729'>4729</a>
<a id='n4730' href='#n4730'>4730</a>
<a id='n4731' href='#n4731'>4731</a>
<a id='n4732' href='#n4732'>4732</a>
<a id='n4733' href='#n4733'>4733</a>
<a id='n4734' href='#n4734'>4734</a>
<a id='n4735' href='#n4735'>4735</a>
<a id='n4736' href='#n4736'>4736</a>
<a id='n4737' href='#n4737'>4737</a>
<a id='n4738' href='#n4738'>4738</a>
<a id='n4739' href='#n4739'>4739</a>
<a id='n4740' href='#n4740'>4740</a>
<a id='n4741' href='#n4741'>4741</a>
<a id='n4742' href='#n4742'>4742</a>
<a id='n4743' href='#n4743'>4743</a>
<a id='n4744' href='#n4744'>4744</a>
<a id='n4745' href='#n4745'>4745</a>
<a id='n4746' href='#n4746'>4746</a>
<a id='n4747' href='#n4747'>4747</a>
<a id='n4748' href='#n4748'>4748</a>
<a id='n4749' href='#n4749'>4749</a>
<a id='n4750' href='#n4750'>4750</a>
<a id='n4751' href='#n4751'>4751</a>
<a id='n4752' href='#n4752'>4752</a>
<a id='n4753' href='#n4753'>4753</a>
<a id='n4754' href='#n4754'>4754</a>
<a id='n4755' href='#n4755'>4755</a>
<a id='n4756' href='#n4756'>4756</a>
<a id='n4757' href='#n4757'>4757</a>
<a id='n4758' href='#n4758'>4758</a>
<a id='n4759' href='#n4759'>4759</a>
<a id='n4760' href='#n4760'>4760</a>
<a id='n4761' href='#n4761'>4761</a>
<a id='n4762' href='#n4762'>4762</a>
<a id='n4763' href='#n4763'>4763</a>
<a id='n4764' href='#n4764'>4764</a>
<a id='n4765' href='#n4765'>4765</a>
<a id='n4766' href='#n4766'>4766</a>
<a id='n4767' href='#n4767'>4767</a>
<a id='n4768' href='#n4768'>4768</a>
<a id='n4769' href='#n4769'>4769</a>
<a id='n4770' href='#n4770'>4770</a>
<a id='n4771' href='#n4771'>4771</a>
<a id='n4772' href='#n4772'>4772</a>
<a id='n4773' href='#n4773'>4773</a>
<a id='n4774' href='#n4774'>4774</a>
<a id='n4775' href='#n4775'>4775</a>
<a id='n4776' href='#n4776'>4776</a>
<a id='n4777' href='#n4777'>4777</a>
<a id='n4778' href='#n4778'>4778</a>
<a id='n4779' href='#n4779'>4779</a>
<a id='n4780' href='#n4780'>4780</a>
<a id='n4781' href='#n4781'>4781</a>
<a id='n4782' href='#n4782'>4782</a>
<a id='n4783' href='#n4783'>4783</a>
<a id='n4784' href='#n4784'>4784</a>
<a id='n4785' href='#n4785'>4785</a>
<a id='n4786' href='#n4786'>4786</a>
<a id='n4787' href='#n4787'>4787</a>
<a id='n4788' href='#n4788'>4788</a>
<a id='n4789' href='#n4789'>4789</a>
<a id='n4790' href='#n4790'>4790</a>
<a id='n4791' href='#n4791'>4791</a>
<a id='n4792' href='#n4792'>4792</a>
<a id='n4793' href='#n4793'>4793</a>
<a id='n4794' href='#n4794'>4794</a>
<a id='n4795' href='#n4795'>4795</a>
<a id='n4796' href='#n4796'>4796</a>
<a id='n4797' href='#n4797'>4797</a>
<a id='n4798' href='#n4798'>4798</a>
<a id='n4799' href='#n4799'>4799</a>
<a id='n4800' href='#n4800'>4800</a>
<a id='n4801' href='#n4801'>4801</a>
<a id='n4802' href='#n4802'>4802</a>
<a id='n4803' href='#n4803'>4803</a>
<a id='n4804' href='#n4804'>4804</a>
<a id='n4805' href='#n4805'>4805</a>
<a id='n4806' href='#n4806'>4806</a>
<a id='n4807' href='#n4807'>4807</a>
<a id='n4808' href='#n4808'>4808</a>
<a id='n4809' href='#n4809'>4809</a>
<a id='n4810' href='#n4810'>4810</a>
<a id='n4811' href='#n4811'>4811</a>
<a id='n4812' href='#n4812'>4812</a>
<a id='n4813' href='#n4813'>4813</a>
<a id='n4814' href='#n4814'>4814</a>
<a id='n4815' href='#n4815'>4815</a>
<a id='n4816' href='#n4816'>4816</a>
<a id='n4817' href='#n4817'>4817</a>
<a id='n4818' href='#n4818'>4818</a>
<a id='n4819' href='#n4819'>4819</a>
<a id='n4820' href='#n4820'>4820</a>
<a id='n4821' href='#n4821'>4821</a>
<a id='n4822' href='#n4822'>4822</a>
<a id='n4823' href='#n4823'>4823</a>
<a id='n4824' href='#n4824'>4824</a>
<a id='n4825' href='#n4825'>4825</a>
<a id='n4826' href='#n4826'>4826</a>
<a id='n4827' href='#n4827'>4827</a>
<a id='n4828' href='#n4828'>4828</a>
<a id='n4829' href='#n4829'>4829</a>
<a id='n4830' href='#n4830'>4830</a>
<a id='n4831' href='#n4831'>4831</a>
<a id='n4832' href='#n4832'>4832</a>
<a id='n4833' href='#n4833'>4833</a>
<a id='n4834' href='#n4834'>4834</a>
<a id='n4835' href='#n4835'>4835</a>
<a id='n4836' href='#n4836'>4836</a>
<a id='n4837' href='#n4837'>4837</a>
<a id='n4838' href='#n4838'>4838</a>
<a id='n4839' href='#n4839'>4839</a>
<a id='n4840' href='#n4840'>4840</a>
<a id='n4841' href='#n4841'>4841</a>
<a id='n4842' href='#n4842'>4842</a>
<a id='n4843' href='#n4843'>4843</a>
<a id='n4844' href='#n4844'>4844</a>
<a id='n4845' href='#n4845'>4845</a>
<a id='n4846' href='#n4846'>4846</a>
<a id='n4847' href='#n4847'>4847</a>
<a id='n4848' href='#n4848'>4848</a>
<a id='n4849' href='#n4849'>4849</a>
<a id='n4850' href='#n4850'>4850</a>
<a id='n4851' href='#n4851'>4851</a>
<a id='n4852' href='#n4852'>4852</a>
<a id='n4853' href='#n4853'>4853</a>
<a id='n4854' href='#n4854'>4854</a>
<a id='n4855' href='#n4855'>4855</a>
<a id='n4856' href='#n4856'>4856</a>
<a id='n4857' href='#n4857'>4857</a>
<a id='n4858' href='#n4858'>4858</a>
<a id='n4859' href='#n4859'>4859</a>
<a id='n4860' href='#n4860'>4860</a>
<a id='n4861' href='#n4861'>4861</a>
<a id='n4862' href='#n4862'>4862</a>
<a id='n4863' href='#n4863'>4863</a>
<a id='n4864' href='#n4864'>4864</a>
<a id='n4865' href='#n4865'>4865</a>
<a id='n4866' href='#n4866'>4866</a>
<a id='n4867' href='#n4867'>4867</a>
<a id='n4868' href='#n4868'>4868</a>
<a id='n4869' href='#n4869'>4869</a>
<a id='n4870' href='#n4870'>4870</a>
<a id='n4871' href='#n4871'>4871</a>
<a id='n4872' href='#n4872'>4872</a>
<a id='n4873' href='#n4873'>4873</a>
<a id='n4874' href='#n4874'>4874</a>
<a id='n4875' href='#n4875'>4875</a>
<a id='n4876' href='#n4876'>4876</a>
<a id='n4877' href='#n4877'>4877</a>
<a id='n4878' href='#n4878'>4878</a>
<a id='n4879' href='#n4879'>4879</a>
<a id='n4880' href='#n4880'>4880</a>
<a id='n4881' href='#n4881'>4881</a>
<a id='n4882' href='#n4882'>4882</a>
<a id='n4883' href='#n4883'>4883</a>
<a id='n4884' href='#n4884'>4884</a>
<a id='n4885' href='#n4885'>4885</a>
<a id='n4886' href='#n4886'>4886</a>
<a id='n4887' href='#n4887'>4887</a>
<a id='n4888' href='#n4888'>4888</a>
<a id='n4889' href='#n4889'>4889</a>
<a id='n4890' href='#n4890'>4890</a>
<a id='n4891' href='#n4891'>4891</a>
<a id='n4892' href='#n4892'>4892</a>
<a id='n4893' href='#n4893'>4893</a>
<a id='n4894' href='#n4894'>4894</a>
<a id='n4895' href='#n4895'>4895</a>
<a id='n4896' href='#n4896'>4896</a>
<a id='n4897' href='#n4897'>4897</a>
<a id='n4898' href='#n4898'>4898</a>
<a id='n4899' href='#n4899'>4899</a>
<a id='n4900' href='#n4900'>4900</a>
<a id='n4901' href='#n4901'>4901</a>
<a id='n4902' href='#n4902'>4902</a>
<a id='n4903' href='#n4903'>4903</a>
<a id='n4904' href='#n4904'>4904</a>
<a id='n4905' href='#n4905'>4905</a>
<a id='n4906' href='#n4906'>4906</a>
<a id='n4907' href='#n4907'>4907</a>
<a id='n4908' href='#n4908'>4908</a>
<a id='n4909' href='#n4909'>4909</a>
<a id='n4910' href='#n4910'>4910</a>
<a id='n4911' href='#n4911'>4911</a>
<a id='n4912' href='#n4912'>4912</a>
<a id='n4913' href='#n4913'>4913</a>
<a id='n4914' href='#n4914'>4914</a>
<a id='n4915' href='#n4915'>4915</a>
<a id='n4916' href='#n4916'>4916</a>
<a id='n4917' href='#n4917'>4917</a>
<a id='n4918' href='#n4918'>4918</a>
<a id='n4919' href='#n4919'>4919</a>
<a id='n4920' href='#n4920'>4920</a>
<a id='n4921' href='#n4921'>4921</a>
<a id='n4922' href='#n4922'>4922</a>
<a id='n4923' href='#n4923'>4923</a>
<a id='n4924' href='#n4924'>4924</a>
<a id='n4925' href='#n4925'>4925</a>
<a id='n4926' href='#n4926'>4926</a>
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<td class='lines'><pre><code><span class="hl kwa">\chapter</span><span class="hl opt">{</span>Basic Facilities of a Virtio Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device<span class="hl opt">}</span>

A virtio device is discovered and identified by a bus-specific method
(see the bus specific sections: <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus<span class="hl opt">}</span>,
<span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over Channel I/O<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over Channel I/O<span class="hl opt">}</span>).  Each
device consists of the following parts:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Device status field
<span class="hl kwa">\item</span> Feature bits
<span class="hl kwa">\item</span> Device Configuration space
<span class="hl kwa">\item</span> One or more virtqueues
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\section</span><span class="hl opt">{</span><span class="hl kwa">\field</span><span class="hl opt">{</span>Device Status<span class="hl opt">}</span> Field<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Status Field<span class="hl opt">}</span>
During device initialization by a driver,
the driver follows the sequence of steps specified in
<span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device
Initialization<span class="hl opt">}</span>.

The <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> field provides a simple low-level
indication of the completed steps of this sequence.
It&apos;s most useful to imagine it hooked up to traffic
lights on the console indicating the status of each device.  The
following bits are defined:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>ACKNOWLEDGE (<span class="hl num">1</span>)<span class="hl opt">]</span> Indicates that the guest OS has found the
  device and recognized it as a valid virtio device.

<span class="hl kwa">\item</span><span class="hl opt">[</span>DRIVER (<span class="hl num">2</span>)<span class="hl opt">]</span> Indicates that the guest OS knows how to drive the
  device.
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
    There could be a significant (or infinite) delay before setting
    this bit.  For example, under Linux, drivers can be loadable modules.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\item</span><span class="hl opt">[</span>FEATURES_OK (<span class="hl num">8</span>)<span class="hl opt">]</span> Indicates that the driver has acknowledged all the
  features it understands, and feature negotiation is complete.

<span class="hl kwa">\item</span><span class="hl opt">[</span>DRIVER_OK (<span class="hl num">4</span>)<span class="hl opt">]</span> Indicates that the driver is set up and ready to
  drive the device.

<span class="hl kwa">\item</span><span class="hl opt">[</span>DEVICE_NEEDS_RESET (<span class="hl num">64</span>)<span class="hl opt">]</span> Indicates that the device has experienced
  an error from which it can&apos;t recover.

<span class="hl kwa">\item</span><span class="hl opt">[</span>FAILED (<span class="hl num">128</span>)<span class="hl opt">]</span> Indicates that something went wrong in the guest,
  and it has given up on the device. This could be an internal
  error, or the driver didn&apos;t like the device for some reason, or
  even a fatal error during device operation.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Status Field<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Device Status Field<span class="hl opt">}</span>
The driver MUST update <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span>,
setting bits to indicate the completed steps of the driver
initialization sequence specified in
<span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device
Initialization<span class="hl opt">}</span>.
The driver MUST NOT clear a
<span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> bit.  If the driver sets the FAILED bit,
the driver MUST later reset the device before attempting to re-initialize.

The driver SHOULD NOT rely on completion of operations of a
device if DEVICE_NEEDS_RESET is set.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, the driver can&apos;t assume requests in flight will be
completed if DEVICE_NEEDS_RESET is set, nor can it assume that
they have not been completed.  A good implementation will try to
recover by issuing a reset.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Status Field<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Device Status Field<span class="hl opt">}</span>
The device MUST initialize <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> to <span class="hl num">0</span> upon reset.

The device MUST NOT consume buffers or notify the driver before DRIVER_OK.

<span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Status Field / DEVICENEEDSRESET<span class="hl opt">}</span>The device SHOULD set DEVICE_NEEDS_RESET when it enters an error state
that a reset is needed.  If DRIVER_OK is set, after it sets DEVICE_NEEDS_RESET, the device
MUST send a device configuration change notification to the driver.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Feature Bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>

Each virtio device offers all the features it understands.  During
device initialization, the driver reads this and tells the device the
subset that it accepts.  The only way to renegotiate is to reset
the device.

This allows for forwards and backwards compatibility: if the device is
enhanced with a new feature bit, older drivers will not write that
feature bit back to the device.  Similarly, if a driver is enhanced with a feature
that the device doesn&apos;t support, it see the new feature is not offered.

Feature bits are allocated as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span> to <span class="hl num">23</span><span class="hl opt">]</span> Feature bits for the specific device type

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">24</span> to <span class="hl num">32</span><span class="hl opt">]</span> Feature bits reserved for extensions to the queue and
  feature negotiation mechanisms

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">33</span> and above<span class="hl opt">]</span> Feature bits reserved for future extensions.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, feature bit <span class="hl num">0</span> for a network device (i.e.
Device ID <span class="hl num">1</span>) indicates that the device supports checksumming of
packets.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

In particular, new fields in the device configuration space are
indicated by offering a new feature bit.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Feature Bits<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>
The driver MUST NOT accept a feature which the device did not offer,
and MUST NOT accept a feature which requires another feature which was
not accepted.

The driver SHOULD go into backwards compatibility mode
if the device does not offer a feature it understands, otherwise MUST
set the FAILED <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> bit and cease initialization.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Feature Bits<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>
The device MUST NOT offer a feature which requires another feature
which was not offered.  The device SHOULD accept any valid subset
of features the driver accepts, otherwise it MUST fail to set the
FEATURES_OK <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> bit when the driver writes it.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interface: A Note on Feature
Bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature
Bits / Legacy Interface: A Note on Feature Bits<span class="hl opt">}</span>

Transitional Drivers MUST detect Legacy Devices by detecting that
the feature bit VIRTIO_F_VERSION_1 is not offered.
Transitional devices MUST detect Legacy drivers by detecting that
VIRTIO_F_VERSION_1 has not been acknowledged by the driver.

In this case device is used through the legacy interface.

Legacy interface support is OPTIONAL.
Thus, both transitional and non-transitional devices and
drivers are compliant with this specification.

Requirements pertaining to transitional devices and drivers
is contained in sections named &apos;Legacy Interface&apos; like this one.

When device is used through the legacy interface, transitional
devices and transitional drivers MUST operate according to the
requirements documented within these legacy interface sections.
Specification text within these sections generally does not apply
to non-transitional devices.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Device Configuration Space<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Configuration Space<span class="hl opt">}</span>

Device configuration space is generally used for rarely-changing or
initialization-time parameters.  Where configuration fields are
optional, their existence is indicated by feature bits: Future
versions of this specification will likely extend the device
configuration space by adding extra fields at the tail.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
The device configuration space uses the little-endian format
for multi-byte fields.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

Each transport also provides a generation count for the device configuration
space, which will change whenever there is a possibility that two
accesses to the device configuration space can see different versions of that
space.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Configuration Space<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Device Configuration Space<span class="hl opt">}</span>
Drivers MUST NOT assume reads from
fields greater than <span class="hl num">32</span> bits wide are atomic, nor are reads from
multiple fields: drivers SHOULD read device configuration space fields like so:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
u32 before, after;
do <span class="hl opt">{</span>
        before = get_config_generation(device);
        // read config entry/entries.
        after = get_config_generation(device);
<span class="hl opt">}</span> while (after != before);
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

For optional configuration space fields, the driver MUST check that the
corresponding feature is offered before accessing that part of the configuration
space.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
See section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span> for details on feature negotiation.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

Drivers MUST
NOT limit structure size and device configuration space size.  Instead,
drivers SHOULD only check that device configuration space is <span class="hl opt">{</span><span class="hl kwa">\em</span> large enough<span class="hl opt">}</span> to
contain the fields necessary for device operation.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, if the specification states that device configuration
space &apos;includes a single <span class="hl num">8</span>-bit field&apos; drivers should understand this to mean that
the device configuration space might also include an arbitrary amount of
tail padding, and accept any device configuration space size equal to or
greater than the specified <span class="hl num">8</span>-bit size.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Configuration Space<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Device Configuration Space<span class="hl opt">}</span>
The device MUST allow reading of any device-specific configuration
field before FEATURES_OK is set by the driver.  This includes fields which are
conditional on feature bits, as long as those feature bits are offered
by the device.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interface: A Note on Device Configuration Space endian-ness<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Configuration Space / Legacy Interface: A Note on Configuration Space endian-ness<span class="hl opt">}</span>

Note that for legacy interfaces, device configuration space is generally the
guest&apos;s native endian, rather than PCI&apos;s little-endian.
The correct endian-ness is documented for each device.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interface: Device Configuration Space<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Configuration Space / Legacy Interface: Device Configuration Space<span class="hl opt">}</span>

Legacy devices did not have a configuration generation field, thus are
susceptible to race conditions if configuration is updated.  This
affects the block <span class="hl kwa">\field</span><span class="hl opt">{</span>capacity<span class="hl opt">}</span> (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types /
Block Device / Device configuration layout<span class="hl opt">}</span>) and
network <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Network Device /
Device configuration layout<span class="hl opt">}</span>) fields;
when using the legacy interface, drivers SHOULD
read these fields multiple times until two reads generate a consistent
result.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>

The mechanism for bulk data transport on virtio devices is
pretentiously called a virtqueue. Each device can have zero or more
virtqueues<span class="hl kwa">\footnote</span><span class="hl opt">{</span>For example, the simplest network device has one virtqueue for
transmit and one for receive.<span class="hl opt">}</span>.  Each queue has a <span class="hl num">16</span>-bit queue size
parameter, which sets the number of entries and implies the total size
of the queue.

Each virtqueue consists of three parts:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Descriptor Table
<span class="hl kwa">\item</span> Available Ring
<span class="hl kwa">\item</span> Used Ring
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

where each part is physically-contiguous in guest memory,
and has different alignment requirements.

The memory aligment and size requirements, in bytes, of each part of the
virtqueue are summarized in the following table:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span>|l|l|l|<span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Virtqueue Part    &amp; Alignment &amp; Size \\
<span class="hl kwa">\hline \hline</span>
Descriptor Table  &amp; <span class="hl num">16</span>        &amp; $<span class="hl num">16</span> * $(Queue Size) \\
<span class="hl kwa">\hline</span>
Available Ring    &amp; <span class="hl num">2</span>         &amp; $<span class="hl num">6</span> + <span class="hl num">2</span> * $(Queue Size) \\
 <span class="hl kwa">\hline</span>
Used Ring         &amp; <span class="hl num">4</span>         &amp; $<span class="hl num">6</span> + <span class="hl num">8</span> * $(Queue Size) \\
 <span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

The Alignment column gives the minimum alignment for each part
of the virtqueue.

The Size column gives the total number of bytes for each
part of the virtqueue.

Queue Size corresponds to the maximum number of buffers in the
virtqueue<span class="hl kwa">\footnote</span><span class="hl opt">{</span>For example, if Queue Size is <span class="hl num">4</span> then at most <span class="hl num">4</span> buffers
can be queued at any given time.<span class="hl opt">}</span>.  Queue Size value is always a
power of <span class="hl num">2</span>.  The maximum Queue Size value is <span class="hl num">32768</span>.  This value
is specified in a bus-specific way.

When the driver wants to send a buffer to the device, it fills in
a slot in the descriptor table (or chains several together), and
writes the descriptor index into the available ring.  It then
notifies the device. When the device has finished a buffer, it
writes the descriptor index into the used ring, and sends an interrupt.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Virtqueues<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>
The driver MUST ensure that the physical address of the first byte
of each virtqueue part is a multiple of the specified alignment value
in the above table.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>

For Legacy Interfaces, several additional
restrictions are placed on the virtqueue layout:

Each virtqueue occupies two or more physically-contiguous pages
(usually defined as <span class="hl num">4096</span> bytes, but depending on the transport;
henceforth referred to as Queue Align)
and consists of three parts:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span>|l|l|l|<span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Descriptor Table &amp; Available Ring (<span class="hl kwa">\ldots</span> padding<span class="hl kwa">\ldots</span>) &amp; Used Ring \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

The bus-specific Queue Size field controls the total number of bytes
for the virtqueue.
When using the legacy interface, the transitional
driver MUST retrieve the Queue Size field from the device
and MUST allocate the total number of bytes for the virtqueue
according to the following formula (Queue Align given in qalign and
Queue Size given in qsz):

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define ALIGN(x) (((x) + qalign) &amp; ~qalign)
static inline unsigned virtq_size(unsigned int qsz)
<span class="hl opt">{</span>
     return ALIGN(sizeof(struct virtq_desc)*qsz + sizeof(u16)*(<span class="hl num">3</span> + qsz))
          + ALIGN(sizeof(u16)*<span class="hl num">3</span> + sizeof(struct virtq_used_elem)*qsz);
<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

This wastes some space with padding.
When using the legacy interface, both transitional
devices and drivers MUST use the following virtqueue layout
structure to locate elements of the virtqueue:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtq <span class="hl opt">{</span>
        // The actual descriptors (<span class="hl num">16</span> bytes each)
        struct virtq_desc desc<span class="hl opt">[</span> Queue Size <span class="hl opt">]</span>;

        // A ring of available descriptor heads with free-running index.
        struct virtq_avail avail;

        // Padding to the next Queue Align boundary.
        u8 pad<span class="hl opt">[</span> Padding <span class="hl opt">]</span>;

        // A ring of used descriptor heads with free-running index.
        struct virtq_used used;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interfaces: A Note on Virtqueue Endianness<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Endianness<span class="hl opt">}</span>

Note that when using the legacy interface, transitional
devices and drivers MUST use the native
endian of the guest as the endian of fields and in the virtqueue.
This is opposed to little-endian for non-legacy interface as
specified by this standard.
It is assumed that the host is already aware of the guest endian.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Message Framing<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing<span class="hl opt">}</span>
The framing of messages with descriptors is
independent of the contents of the buffers. For example, a network
transmit buffer consists of a <span class="hl num">12</span> byte header followed by the network
packet. This could be most simply placed in the descriptor table as a
<span class="hl num">12</span> byte output descriptor followed by a <span class="hl num">1514</span> byte output descriptor,
but it could also consist of a single <span class="hl num">1526</span> byte output descriptor in
the case where the header and packet are adjacent, or even three or
more descriptors (possibly with loss of efficiency in that case).

Note that, some device implementations have large-but-reasonable
restrictions on total descriptor size (such as based on IOV_MAX in the
host OS). This has not been a problem in practice: little sympathy
will be given to drivers which create unreasonably-sized descriptors
such as by dividing a network packet into <span class="hl num">1500</span> single-byte
descriptors!

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Message Framing<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Message Framing<span class="hl opt">}</span>
The device MUST NOT make assumptions about the particular arrangement
of descriptors.  The device MAY have a reasonable limit of descriptors
it will allow in a chain.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Message Framing<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Message Framing<span class="hl opt">}</span>
The driver MUST place any device-writable descriptor elements after
any device-readable descriptor elements.

The driver SHOULD NOT use an excessive number of descriptors to
describe a buffer.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Message Framing<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing<span class="hl opt">}</span>

Regrettably, initial driver implementations used simple layouts, and
devices came to rely on it, despite this specification wording.  In
addition, the specification for virtio_blk SCSI commands required
intuiting field lengths from frame boundaries (see
 <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Operation / Legacy Interface: Device Operation<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Operation / Legacy Interface: Device Operation<span class="hl opt">}</span>)

Thus when using the legacy interface, the VIRTIO_F_ANY_LAYOUT
feature indicates to both the device and the driver that no
assumptions were made about framing.  Requirements for
transitional drivers when this is not negotiated are included in
each device section.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>The Virtqueue Descriptor Table<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table<span class="hl opt">}</span>

The descriptor table refers to the buffers the driver is using for
the device. <span class="hl kwa">\field</span><span class="hl opt">{</span>addr<span class="hl opt">}</span> is a physical address, and the buffers
can be chained via <span class="hl kwa">\field</span><span class="hl opt">{</span>next<span class="hl opt">}</span>. Each descriptor describes a
buffer which is read-only for the device (``device-readable&apos;&apos;) or write-only for the device (``device-writable&apos;&apos;), but a chain of
descriptors can contain both device-readable and device-writable buffers.

The actual contents of the memory offered to the device depends on the
device type.  Most common is to begin the data with a header
(containing little-endian fields) for the device to read, and postfix
it with a status tailer for the device to write.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtq_desc <span class="hl opt">{</span>
        /* Address (guest-physical). */
        le64 addr;
        /* Length. */
        le32 len;

/* This marks a buffer as continuing via the next field. */
#define VIRTQ_DESC_F_NEXT   <span class="hl num">1</span>
/* This marks a buffer as device write-only (otherwise device read-only). */
#define VIRTQ_DESC_F_WRITE     <span class="hl num">2</span>
/* This means the buffer contains a list of buffer descriptors. */
#define VIRTQ_DESC_F_INDIRECT   <span class="hl num">4</span>
        /* The flags as indicated above. */
        le16 flags;
        /* Next field if flags &amp; NEXT */
        le16 next;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The number of descriptors in the table is defined by the queue size
for this virtqueue: this is the maximum possible descriptor chain length.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
The legacy <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:Virtio PCI Draft<span class="hl opt">]{[</span>Virtio PCI Draft<span class="hl opt">]}</span>
referred to this structure as vring_desc, and the constants as
VRING_DESC_F_NEXT, etc, but the layout and values were identical.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>The Virtqueue Descriptor Table<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table<span class="hl opt">}</span>
A device MUST NOT write to a device-readable buffer, and a device SHOULD NOT
read a device-writable buffer (it MAY do so for debugging or diagnostic
purposes).

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>The Virtqueue Descriptor Table<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table<span class="hl opt">}</span>
Drivers MUST NOT add a descriptor chain over than $<span class="hl num">2</span>^<span class="hl opt">{</span><span class="hl num">32</span><span class="hl opt">}</span>$ bytes long in total;
this implies that loops in the descriptor chain are forbidden!

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Indirect Descriptors<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors<span class="hl opt">}</span>

Some devices benefit by concurrently dispatching a large number
of large requests. The VIRTIO_F_INDIRECT_DESC feature allows this (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:virtio-ring.h<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:virtio-ring.h<span class="hl opt">}</span>). To increase
ring capacity the driver can store a table of indirect
descriptors anywhere in memory, and insert a descriptor in main
virtqueue (with <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span>\&amp;VIRTQ_DESC_F_INDIRECT on) that refers to memory buffer
containing this indirect descriptor table; <span class="hl kwa">\field</span><span class="hl opt">{</span>addr<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>len<span class="hl opt">}</span>
refer to the indirect table address and length in bytes,
respectively.

The indirect table layout structure looks like this
(<span class="hl kwa">\field</span><span class="hl opt">{</span>len<span class="hl opt">}</span> is the length of the descriptor that refers to this table,
which is a variable, so this code won&apos;t compile):

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct indirect_descriptor_table <span class="hl opt">{</span>
        /* The actual descriptors (<span class="hl num">16</span> bytes each) */
        struct virtq_desc desc<span class="hl opt">[</span>len / <span class="hl num">16</span><span class="hl opt">]</span>;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The first indirect descriptor is located at start of the indirect
descriptor table (index <span class="hl num">0</span>), additional indirect descriptors are
chained by <span class="hl kwa">\field</span><span class="hl opt">{</span>next<span class="hl opt">}</span>. An indirect descriptor without a valid <span class="hl kwa">\field</span><span class="hl opt">{</span>next<span class="hl opt">}</span>
(with <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span>\&amp;VIRTQ_DESC_F_NEXT off) signals the end of the descriptor.
A single indirect descriptor
table can include both device-readable and device-writable descriptors.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Indirect Descriptors<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors<span class="hl opt">}</span>
The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT flag unless the
VIRTIO_F_INDIRECT_DESC feature was negotiated.   The driver MUST NOT
set the VIRTQ_DESC_F_INDIRECT flag within an indirect descriptor (ie. only
one table per descriptor).

A driver MUST NOT create a descriptor chain longer than the Queue Size of
the device.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Indirect Descriptors<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors<span class="hl opt">}</span>
The device MUST ignore the write-only flag (<span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span>\&amp;VIRTQ_DESC_F_WRITE) in the descriptor that refers to an indirect table.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>The Virtqueue Available Ring<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Available Ring<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtq_avail <span class="hl opt">{</span>
#define VIRTQ_AVAIL_F_NO_INTERRUPT      <span class="hl num">1</span>
        le16 flags;
        le16 idx;
        le16 ring<span class="hl opt">[</span> /* Queue Size */ <span class="hl opt">]</span>;
        le16 used_event; /* Only if VIRTIO_F_EVENT_IDX */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The driver uses the available ring to offer buffers to the
device: each ring entry refers to the head of a descriptor chain.  It is only
written by the driver and read by the device.

<span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> field indicates where the driver would put the next descriptor
entry in the ring (modulo the queue size). This starts at <span class="hl num">0</span>, and increases.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
The legacy <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:Virtio PCI Draft<span class="hl opt">]{[</span>Virtio PCI Draft<span class="hl opt">]}</span>
referred to this structure as vring_avail, and the constant as
VRING_AVAIL_F_NO_INTERRUPT, but the layout and value were identical.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueue Interrupt Suppression<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span>

If the VIRTIO_F_EVENT_IDX feature bit is not negotiated,
the <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> field in the available ring offers a crude mechanism for the driver to inform
the device that it doesn&apos;t want interrupts when buffers are used.  Otherwise
<span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> is a more performant alterative where the driver
specifies how far the device can progress before interrupting.

Neither of these interrupt suppression methods are reliable, as they
are not synchronized with the device, but they serve as
useful optimizations.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtqueue Interrupt Suppression<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span>
If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">0</span> or <span class="hl num">1</span>.
<span class="hl kwa">\item</span> The driver MAY set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">1</span> to advise
the device that interrupts are not needed.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

Otherwise, if the VIRTIO_F_EVENT_IDX feature bit is negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">0</span>.
<span class="hl kwa">\item</span> The driver MAY use <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> to advise the device that interrupts are unnecessary until the device writes entry with an index specified by <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> into the used ring (equivalently, until <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> in the
used ring will reach the value <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> + <span class="hl num">1</span>).
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

The driver MUST handle spurious interrupts from the device.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtqueue Interrupt Suppression<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span>

If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device MUST ignore the <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> value.
<span class="hl kwa">\item</span> After the device writes a descriptor index into the used ring:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> is <span class="hl num">1</span>, the device SHOULD NOT send an interrupt.
  <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> is <span class="hl num">0</span>, the device MUST send an interrupt.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

Otherwise, if the VIRTIO_F_EVENT_IDX feature bit is negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device MUST ignore the lower bit of <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span>.
<span class="hl kwa">\item</span> After the device writes a descriptor index into the used ring:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If the <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> field in the used ring (which determined
    where that descriptor index was placed) was equal to
    <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span>, the device MUST send an interrupt.
  <span class="hl kwa">\item</span> Otherwise the device SHOULD NOT send an interrupt.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, if <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> is <span class="hl num">0</span>, then a device using
  VIRTIO_F_EVENT_IDX would interrupt after the first buffer is
  used (and again after the <span class="hl num">65536</span>th buffer, etc).
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>The Virtqueue Used Ring<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtq_used <span class="hl opt">{</span>
#define VIRTQ_USED_F_NO_NOTIFY  <span class="hl num">1</span>
        le16 flags;
        le16 idx;
        struct virtq_used_elem ring<span class="hl opt">[</span> /* Queue Size */<span class="hl opt">]</span>;
        le16 avail_event; /* Only if VIRTIO_F_EVENT_IDX */
<span class="hl opt">}</span>;

/* le32 is used here for ids for padding reasons. */
struct virtq_used_elem <span class="hl opt">{</span>
        /* Index of start of used descriptor chain. */
        le32 id;
        /* Total length of the descriptor chain which was used (written to) */
        le32 len;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The used ring is where the device returns buffers once it is done with
them: it is only written to by the device, and read by the driver.

Each entry in the ring is a pair: <span class="hl kwa">\field</span><span class="hl opt">{</span>id<span class="hl opt">}</span> indicates the head entry of the
descriptor chain describing the buffer (this matches an entry
placed in the available ring by the guest earlier), and <span class="hl kwa">\field</span><span class="hl opt">{</span>len<span class="hl opt">}</span> the total
of bytes written into the buffer. The latter is extremely useful
for drivers using untrusted buffers: if you do not know exactly
how much has been written by the device, you usually have to zero
the buffer to ensure no data leakage occurs.

<span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> field indicates where the driver would put the next descriptor
entry in the ring (modulo the queue size). This starts at <span class="hl num">0</span>, and increases.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
The legacy <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:Virtio PCI Draft<span class="hl opt">]{[</span>Virtio PCI Draft<span class="hl opt">]}</span>
referred to these structures as vring_used and vring_used_elem, and
the constant as VRING_USED_F_NO_NOTIFY, but the layout and value were
identical.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueue Notification Suppression<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Notification Suppression<span class="hl opt">}</span>

The device can suppress notifications in a manner analogous to the way
drivers can suppress interrupts as detailed in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span>.
The device manipulates <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> or <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> in the used ring the
same way the driver manipulates <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> or <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> in the available ring.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtqueue Notification Suppression<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Notification Suppression<span class="hl opt">}</span>

The driver MUST initialize <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> in the used ring to <span class="hl num">0</span> when
allocating the used ring.

If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver MUST ignore the <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> value.
<span class="hl kwa">\item</span> After the driver writes a descriptor index into the available ring:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
        <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> is <span class="hl num">1</span>, the driver SHOULD NOT send a notification.
        <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> is <span class="hl num">0</span>, the driver MUST send a notification.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

Otherwise, if the VIRTIO_F_EVENT_IDX feature bit is negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver MUST ignore the lower bit of <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span>.
<span class="hl kwa">\item</span> After the driver writes a descriptor index into the available ring:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
        <span class="hl kwa">\item</span> If the <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> field in the available ring (which determined
          where that descriptor index was placed) was equal to
          <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span>, the driver MUST send a notification.
        <span class="hl kwa">\item</span> Otherwise the driver SHOULD NOT send a notification.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtqueue Notification Suppression<span class="hl opt">}{</span>Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Notification Suppression<span class="hl opt">}</span>
If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">0</span> or <span class="hl num">1</span>.
<span class="hl kwa">\item</span> The device MAY set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">1</span> to advise
the driver that notifications are not needed.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

Otherwise, if the VIRTIO_F_EVENT_IDX feature bit is negotiated:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to <span class="hl num">0</span>.
<span class="hl kwa">\item</span> The device MAY use <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> to advise the driver that notifications are unnecessary until the driver writes entry with an index specified by <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> into the available ring (equivalently, until <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> in the
available ring will reach the value <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> + <span class="hl num">1</span>).
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

The device MUST handle spurious notifications from the driver.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Helpers for Operating Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Helpers for Operating Virtqueues<span class="hl opt">}</span>

The Linux Kernel Source code contains the definitions above and
helper routines in a more usable form, in
include/uapi/linux/virtio_ring.h. This was explicitly licensed by IBM
and Red Hat under the (<span class="hl num">3</span>-clause) BSD license so that it can be
freely used by all other projects, and is reproduced (with slight
variation to remove Linux assumptions) in <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:virtio-ring.h<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:virtio-ring.h<span class="hl opt">}</span>.

<span class="hl kwa">\chapter</span><span class="hl opt">{</span>General Initialization And Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation<span class="hl opt">}</span>

We start with an overview of device initialization, then expand on the
details of the device and how each step is preformed.  This section
is best read along with the bus-specific section which describes
how to communicate with the specific device.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Initialization<span class="hl opt">}{</span>General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>
The driver MUST follow this sequence to initialize a device:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Reset the device.

<span class="hl kwa">\item</span> Set the ACKNOWLEDGE status bit: the guest OS has notice the device.

<span class="hl kwa">\item</span> Set the DRIVER status bit: the guest OS knows how to drive the device.

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation /
Device Initialization / Read feature bits<span class="hl opt">}</span> Read device feature bits, and write the subset of feature bits
   understood by the OS and driver to the device.  During this step the
   driver MAY read (but MUST NOT write) the device-specific configuration fields to check that it can support the device before accepting it.

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Set FEATURES-OK<span class="hl opt">}</span> Set the FEATURES_OK status bit.  The driver MUST NOT accept
   new feature bits after this step.

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Re-read FEATURES-OK<span class="hl opt">}</span> Re-read <span class="hl kwa">\field</span><span class="hl opt">{</span>device status<span class="hl opt">}</span> to ensure the FEATURES_OK bit is still
   set: otherwise, the device does not support our subset of features
   and the device is unusable.

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Device-specific Setup<span class="hl opt">}</span> Perform device-specific setup, including discovery of virtqueues for the
   device, optional per-bus setup, reading and possibly writing the
   device&apos;s virtio configuration space, and population of virtqueues.

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Set DRIVER-OK<span class="hl opt">}</span> Set the DRIVER_OK status bit.  At this point the device is
   ``live&apos;&apos;.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

If any of these steps go irrecoverably wrong, the driver SHOULD
set the FAILED status bit to indicate that it has given up on the
device (it can reset the device later to restart if desired).  The
driver MUST NOT continue initialization in that case.

The driver MUST NOT notify the device before setting DRIVER_OK.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy Interface: Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization / Legacy Interface: Device Initialization<span class="hl opt">}</span>
Legacy devices did not support the FEATURES_OK status bit, and thus did
not have a graceful way for the device to indicate unsupported feature
combinations.  They also did not provide a clear mechanism to end
feature negotiation, which meant that devices finalized features on
first-use, and no features could be introduced which radically changed
the initial operation of the device.

Legacy driver implementations often used the device before setting the
DRIVER_OK bit, and sometimes even before writing the feature bits
to the device.

The result was the steps <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And
Device Operation / Device Initialization / Set FEATURES-OK<span class="hl opt">}</span> and
<span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device
Initialization / Re-read FEATURES-OK<span class="hl opt">}</span> were omitted, and steps
<span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation /
Device Initialization / Read feature bits<span class="hl opt">}</span>,
<span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Device-specific Setup<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Initialization / Set DRIVER-OK<span class="hl opt">}</span>
were conflated.

Therefore, when using the legacy interface:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span>
The transitional driver MUST execute the initialization
sequence as described in <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device
Operation / Device Initialization<span class="hl opt">}</span>
but omitting the steps <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device
Operation / Device Initialization / Set FEATURES-OK<span class="hl opt">}</span> and
<span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device
Initialization / Re-read FEATURES-OK<span class="hl opt">}</span>.

<span class="hl kwa">\item</span>
The transitional device MUST support the driver
writing device configuration fields
before the step <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation /
Device Initialization / Read feature bits<span class="hl opt">}</span>.
<span class="hl kwa">\item</span>
The transitional device MUST support the driver
using the device before the step <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization
And Device Operation / Device Initialization / Set DRIVER-OK<span class="hl opt">}</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\section</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation<span class="hl opt">}</span>

There are two parts to device operation: supplying new buffers to
the device, and processing used buffers from the device.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span> As an
example, the simplest virtio network device has two virtqueues: the
transmit virtqueue and the receive virtqueue. The driver adds
outgoing (device-readable) packets to the transmit virtqueue, and then
frees them after they are used. Similarly, incoming (device-writable)
buffers are added to the receive virtqueue, and processed after
they are used.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Supplying Buffers to The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device<span class="hl opt">}</span>

The driver offers buffers to one of the device&apos;s virtqueues as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Place Buffers<span class="hl opt">}</span> The driver places the buffer into free descriptor(s) in the
   descriptor table, chaining as necessary (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table<span class="hl opt">}</span>).

<span class="hl kwa">\item\label</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Place Index<span class="hl opt">}</span> The driver places the index of the head of the descriptor chain
   into the next ring entry of the available ring.

<span class="hl kwa">\item</span> Steps <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Place Buffers<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>itm:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Place Index<span class="hl opt">}</span> MAY be performed repeatedly if batching
  is possible.

<span class="hl kwa">\item</span> The driver performs suitable a memory barrier to ensure the device sees
  the updated descriptor table and available ring before the next
  step.

<span class="hl kwa">\item</span> The available <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> is increased by the number of
  descriptor chain heads added to the available ring.

<span class="hl kwa">\item</span> The driver performs a suitable memory barrier to ensure that it updates
  the <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> field before checking for notification suppression.

<span class="hl kwa">\item</span> If notifications are not suppressed, the driver notifies the device
    of the new available buffers.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

Note that the above code does not take precautions against the
available ring buffer wrapping around: this is not possible since
the ring buffer is the same size as the descriptor table, so step
(<span class="hl num">1</span>) will prevent such a condition.

In addition, the maximum queue size is <span class="hl num">32768</span> (the highest power
of <span class="hl num">2</span> which fits in <span class="hl num">16</span> bits), so the <span class="hl num">16</span>-bit <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> value can always
distinguish between a full and empty buffer.

What follows is the requirements of each stage in more detail.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Placing Buffers Into The Descriptor Table<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Placing Buffers Into The Descriptor Table<span class="hl opt">}</span>

A buffer consists of zero or more device-readable physically-contiguous
elements followed by zero or more physically-contiguous
device-writable elements (each has at least one element). This
algorithm maps it into the descriptor table to form a descriptor
chain:

for each buffer element, b:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Get the next free descriptor table entry, d
<span class="hl kwa">\item</span> Set <span class="hl kwa">\field</span><span class="hl opt">{</span>d.addr<span class="hl opt">}</span> to the physical address of the start of b
<span class="hl kwa">\item</span> Set <span class="hl kwa">\field</span><span class="hl opt">{</span>d.len<span class="hl opt">}</span> to the length of b.
<span class="hl kwa">\item</span> If b is device-writable, set <span class="hl kwa">\field</span><span class="hl opt">{</span>d.flags<span class="hl opt">}</span> to VIRTQ_DESC_F_WRITE,
    otherwise <span class="hl num">0</span>.
<span class="hl kwa">\item</span> If there is a buffer element after this:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> Set <span class="hl kwa">\field</span><span class="hl opt">{</span>d.next<span class="hl opt">}</span> to the index of the next free descriptor
      element.
    <span class="hl kwa">\item</span> Set the VIRTQ_DESC_F_NEXT bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>d.flags<span class="hl opt">}</span>.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

In practice, <span class="hl kwa">\field</span><span class="hl opt">{</span>d.next<span class="hl opt">}</span> is usually used to chain free
descriptors, and a separate count kept to check there are enough
free descriptors before beginning the mappings.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Updating The Available Ring<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Updating The Available Ring<span class="hl opt">}</span>

The descriptor chain head is the first d in the algorithm
above, ie. the index of the descriptor table entry referring to the first
part of the buffer.  A naive driver implementation MAY do the following (with the
appropriate conversion to-and-from little-endian assumed):

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
avail-&gt;ring<span class="hl opt">[</span>avail-&gt;idx <span class="hl slc">% qsz] = head;</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

However, in general the driver MAY add many descriptor chains before it updates
<span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> (at which point they become visible to the
device), so it is common to keep a counter of how many the driver has added:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
avail-&gt;ring<span class="hl opt">[</span>(avail-&gt;idx + added++) <span class="hl slc">% qsz] = head;</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Updating <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Updating idx<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> always increments, and wraps naturally at
<span class="hl num">65536</span>:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
avail-&gt;idx += added;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

Once available <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> is updated by the driver, this exposes the
descriptor and its contents.  The device MAY
access the descriptor chains the driver created and the
memory they refer to immediately.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Updating idx<span class="hl opt">}{</span>General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Updating idx<span class="hl opt">}</span>
The driver MUST perform a suitable memory barrier before the <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> update, to ensure the
device sees the most up-to-date copy.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notifying The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Notifying The Device<span class="hl opt">}</span>

The actual method of device notification is bus-specific, but generally
it can be expensive.  So the device MAY suppress such notifications if it
doesn&apos;t need them, as detailed in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Notification Suppression<span class="hl opt">}</span>.

The driver has to be careful to expose the new <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span>
value before checking if notifications are suppressed.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Notifying The Device<span class="hl opt">}{</span>General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Notifying The Device<span class="hl opt">}</span>
The driver MUST perform a suitable memory barrier before reading <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> or
<span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span>, to avoid missing a notification.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Receiving Used Buffers From The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device<span class="hl opt">}</span>

Once the device has used buffers referred to by a descriptor (read from or written to them, or
parts of both, depending on the nature of the virtqueue and the
device), it interrupts the driver as detailed in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span>.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For optimal performance, a driver MAY disable interrupts while processing
the used ring, but beware the problem of missing interrupts between
emptying the ring and reenabling interrupts.  This is usually handled by
re-checking for more used buffers after interrups are re-enabled:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
virtq_disable_interrupts(vq);

for (;;) <span class="hl opt">{</span>
        if (vq-&gt;last_seen_used != le16_to_cpu(virtq-&gt;used.idx)) <span class="hl opt">{</span>
                virtq_enable_interrupts(vq);
                mb();

                if (vq-&gt;last_seen_used != le16_to_cpu(virtq-&gt;used.idx))
                        break;

                virtq_disable_interrupts(vq);
        <span class="hl opt">}</span>

        struct virtq_used_elem *e = virtq.used-&gt;ring<span class="hl opt">[</span>vq-&gt;last_seen_used<span class="hl slc">%vsz];</span>
        process_buffer(e);
        vq-&gt;last_seen_used++;
<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Notification of Device Configuration Changes<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Notification of Device Configuration Changes<span class="hl opt">}</span>

For devices where the device-specific configuration information can be changed, an
interrupt is delivered when a device-specific configuration change occurs.

In addition, this interrupt is triggered by the device setting
DEVICE_NEEDS_RESET (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Status Field / DEVICENEEDSRESET<span class="hl opt">}</span>).

<span class="hl kwa">\section</span><span class="hl opt">{</span>Device Cleanup<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Cleanup<span class="hl opt">}</span>

Once the driver has set the DRIVER_OK status bit, all the configured
virtqueue of the device are considered live.  None of the virtqueues
of a device are live once the device has been reset.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Cleanup<span class="hl opt">}{</span>General Initialization And Device Operation / Device Cleanup<span class="hl opt">}</span>

A driver MUST NOT alter descriptor table entries which have been
exposed in the available ring (and not marked consumed by the device
in the used ring) of a live virtqueue.

A driver MUST NOT decrement the available <span class="hl kwa">\field</span><span class="hl opt">{</span>idx<span class="hl opt">}</span> on a live virtqueue (ie.
there is no way to ``unexpose&apos;&apos; buffers).

Thus a driver MUST ensure a virtqueue isn&apos;t live (by device reset) before removing exposed buffers.

<span class="hl kwa">\chapter</span><span class="hl opt">{</span>Virtio Transport Options<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options<span class="hl opt">}</span>

Virtio can use various different buses, thus the standard is split
into virtio general and bus-specific sections.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Virtio Over PCI Bus<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus<span class="hl opt">}</span>

Virtio devices are commonly implemented as PCI devices.

A Virtio device can be implemented as any kind of PCI device:
a Conventional PCI device or a PCI Express
device.  To assure designs meet the latest level
requirements, see 
the PCI-SIG home page at <span class="hl kwa">\url</span><span class="hl opt">{</span>http://www.pcisig.com<span class="hl opt">}</span> for any
approved changes.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Virtio Over PCI Bus<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus<span class="hl opt">}</span>
A Virtio device using Virtio Over PCI Bus MUST expose to
guest an interface that meets the specification requirements of
the appropriate PCI specification: <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:PCI<span class="hl opt">]{[</span>PCI<span class="hl opt">]}</span>
and <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:PCIe<span class="hl opt">]{[</span>PCIe<span class="hl opt">]}</span>
respectively. 

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>PCI Device Discovery<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery<span class="hl opt">}</span>

Any PCI device with PCI Vendor ID <span class="hl num">0x1AF4</span>, and PCI Device ID <span class="hl num">0x1000</span> through
<span class="hl num">0x107F</span> inclusive is a virtio device. The actual value within this range
indicates which virtio device is supported by the device.
The PCI Device ID is calculated by adding <span class="hl num">0x1040</span> to the Virtio Device ID,
as indicated in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span>.
Additionally, devices MAY utilize a Transitional PCI Device ID range,
<span class="hl num">0x1000</span> to <span class="hl num">0x103F</span> depending on the device type.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>PCI Device Discovery<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery<span class="hl opt">}</span>

Devices MUST have the PCI Vendor ID <span class="hl num">0x1AF4</span>.
Devices MUST either have the PCI Device ID calculated by adding <span class="hl num">0x1040</span>
to the Virtio Device ID, as indicated in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device
Types<span class="hl opt">}</span> or have the Transitional PCI Device ID depending on the device type,
as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span>|l|c|<span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Transitional PCI Device ID  &amp;  Virtio Device    \\
<span class="hl kwa">\hline \hline</span>
<span class="hl num">0x1000</span>      &amp;   network card     \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1001</span>     &amp;   block device     \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1002</span>     &amp; memory ballooning (legacy)  \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1003</span>     &amp;      console       \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1004</span>     &amp;     SCSI host      \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1005</span>     &amp;  entropy source    \\
<span class="hl kwa">\hline</span>
<span class="hl num">0x1009</span>     &amp;   <span class="hl num">9</span>P transport     \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

For example, the network card device with the Virtio Device ID <span class="hl num">1</span>
has the PCI Device ID <span class="hl num">0x1041</span> or the Transitional PCI Device ID <span class="hl num">0x1000</span>.

The PCI Subsystem Vendor ID and the PCI Subsystem Device ID MAY reflect
the PCI Vendor and Device ID of the environment (for informational purposes by the driver).

Non-transitional devices SHOULD have a PCI Device ID in the range
<span class="hl num">0x1040</span> to <span class="hl num">0x107f</span>.
Non-transitional devices SHOULD have a PCI Revision ID of <span class="hl num">1</span> or higher.
Non-transitional devices SHOULD have a PCI Subsystem Device ID of <span class="hl num">0x40</span> or higher.

This is to reduce the chance of a legacy driver attempting
to drive the device.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>PCI Device Discovery<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery<span class="hl opt">}</span>
Drivers MUST match devices with the PCI Vendor ID <span class="hl num">0x1AF4</span> and
the PCI Device ID in the range <span class="hl num">0x1040</span> to <span class="hl num">0x107f</span>,
calculated by adding <span class="hl num">0x1040</span> to the Virtio Device ID,
as indicated in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span>.
Drivers for device types listed in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio
Transport Options / Virtio Over PCI Bus / PCI Device Discovery<span class="hl opt">}</span>
MUST match devices with the PCI Vendor ID <span class="hl num">0x1AF4</span> and
the Transitional PCI Device ID indicated in section
 <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio
Transport Options / Virtio Over PCI Bus / PCI Device Discovery<span class="hl opt">}</span>.

Drivers MUST match any PCI Revision ID value.
Drivers MAY match any PCI Subsystem Vendor ID and any
PCI Subsystem Device ID value.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interfaces: A Note on PCI Device Discovery<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery / Legacy Interfaces: A Note on PCI Device Discovery<span class="hl opt">}</span>
Transitional devices MUST have a PCI Revision ID of <span class="hl num">0</span>.
Transitional devices MUST have the PCI Subsystem Device ID
matching the Virtio Device ID, as indicated in section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span>.
Transitional devices MUST have the Transitional PCI Device ID in
the range <span class="hl num">0x1000</span> to <span class="hl num">0x103f</span>.

This is to match legacy drivers.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>PCI Device Layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout<span class="hl opt">}</span>

The device is configured via I/O and/or memory regions (though see
<span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability<span class="hl opt">}</span>
for access via the PCI configuration space), as specified by Virtio
Structure PCI Capabilities.

Fields of different sizes are present in the device
configuration regions.
All <span class="hl num">32</span>-bit and <span class="hl num">16</span>-bit fields are little-endian.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>PCI Device Layout<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout<span class="hl opt">}</span>

The driver
MUST access each field using the ``natural&apos;&apos; access method, i.e.
<span class="hl num">32</span>-bit accesses for <span class="hl num">32</span>-bit fields, <span class="hl num">16</span>-bit accesses for <span class="hl num">16</span>-bit
fields and <span class="hl num">8</span>-bit accesses for <span class="hl num">8</span>-bit fields.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtio Structure PCI Capabilities<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / Virtio Structure PCI Capabilities<span class="hl opt">}</span>

The virtio device configuration layout includes several structures:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Common configuration
<span class="hl kwa">\item</span> Notifications
<span class="hl kwa">\item</span> ISR Status
<span class="hl kwa">\item</span> Device-specific configuration (optional)
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

Each structure can be mapped by a Base Address register (BAR) belonging to
the function, or accessed via the special VIRTIO_PCI_CAP_PCI_CFG field in the PCI configuration space.

The location of each structure is specified using a vendor-specific PCI capability located
on the capability list in PCI configuration space of the device.
This virtio structure capability uses little-endian format; all fields are
read-only for the driver unless stated otherwise:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_pci_cap <span class="hl opt">{</span>
        u8 cap_vndr;    /* Generic PCI field: PCI_CAP_ID_VNDR */
        u8 cap_next;    /* Generic PCI field: next ptr. */
        u8 cap_len;     /* Generic PCI field: capability length */
        u8 cfg_type;    /* Identifies the structure. */
        u8 bar;         /* Where to find it. */
        u8 padding<span class="hl opt">[</span><span class="hl num">3</span><span class="hl opt">]</span>;  /* Pad to full dword. */
        le32 offset;    /* Offset within bar. */
        le32 length;    /* Length of the structure, in bytes. */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

This structure can be followed by extra data, depending on
<span class="hl kwa">\field</span><span class="hl opt">{</span>cfg_type<span class="hl opt">}</span>, as documented below.

The fields are interpreted as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cap_vndr<span class="hl opt">}]</span>
        <span class="hl num">0x09</span>; Identifies a vendor-specific capability.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cap_next<span class="hl opt">}]</span>
        Link to next capability in the capability list in the PCI configuration space.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cap_len<span class="hl opt">}]</span>
        Length of this capability structure, including the whole of
        struct virtio_pci_cap, and extra data if any.
        This length MAY include padding, or fields unused by the driver.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cfg_type<span class="hl opt">}]</span>
        identifies the structure, according to the following table:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
/* Common configuration */
#define VIRTIO_PCI_CAP_COMMON_CFG        <span class="hl num">1</span>
/* Notifications */
#define VIRTIO_PCI_CAP_NOTIFY_CFG        <span class="hl num">2</span>
/* ISR Status */
#define VIRTIO_PCI_CAP_ISR_CFG           <span class="hl num">3</span>
/* Device specific configuration */
#define VIRTIO_PCI_CAP_DEVICE_CFG        <span class="hl num">4</span>
/* PCI configuration access */
#define VIRTIO_PCI_CAP_PCI_CFG           <span class="hl num">5</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

        Any other value is reserved for future use.

        Each structure is detailed individually below.

        The device MAY offer more than one structure of any type - this makes it
        possible for the device to expose multiple interfaces to drivers.  The order of
        the capabilities in the capability list specifies the order of preference
        suggested by the device.
        <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
          For example, on some hypervisors, notifications using IO accesses are
        faster than memory accesses. In this case, the device would expose two
        capabilities with <span class="hl kwa">\field</span><span class="hl opt">{</span>cfg_type<span class="hl opt">}</span> set to VIRTIO_PCI_CAP_NOTIFY_CFG:
        the first one addressing an I/O BAR, the second one addressing a memory BAR.
        In this example, the driver would use the I/O BAR if I/O resources are available, and fall back on
        memory BAR when I/O resources are unavailable.
        <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>bar<span class="hl opt">}]</span>
        values <span class="hl num">0x0</span> to <span class="hl num">0x5</span> specify a Base Address register (BAR) belonging to
        the function located beginning at <span class="hl num">10</span>h in PCI Configuration Space
        and used to map the structure into Memory or I/O Space.
        The BAR is permitted to be either <span class="hl num">32</span>-bit or <span class="hl num">64</span>-bit, it can map Memory Space
        or I/O Space.

        Any other value is reserved for future use.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}]</span>
        indicates where the structure begins relative to the base address associated
        with the BAR.  The alignment requirements of <span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}</span> are indicated
        in each structure-specific section below.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}]</span>
        indicates the length of the structure.

        <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span> MAY include padding, or fields unused by the driver, or
        future extensions.

        <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
        For example, a future device might present a large structure size of several
        MBytes.
        As current devices never utilize structures larger than <span class="hl num">4</span>KBytes in size,
        driver MAY limit the mapped structure size to e.g.
        <span class="hl num">4</span>KBytes (thus ignoring parts of structure after the first
        <span class="hl num">4</span>KBytes) to allow forward compatibility with such devices without loss of
        functionality and without wasting resources.
        <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtio Structure PCI Capabilities<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / Virtio Structure PCI Capabilities<span class="hl opt">}</span>

The driver MUST ignore any vendor-specific capability structure which has
a reserved <span class="hl kwa">\field</span><span class="hl opt">{</span>cfg_type<span class="hl opt">}</span> value.

The driver SHOULD use the first instance of each virtio structure type they can
support.

The driver MUST accept a <span class="hl kwa">\field</span><span class="hl opt">{</span>cap_len<span class="hl opt">}</span> value which is larger than specified here.

The driver MUST ignore any vendor-specific capability structure which has
a reserved <span class="hl kwa">\field</span><span class="hl opt">{</span>bar<span class="hl opt">}</span> value.

        The drivers SHOULD only map part of configuration structure
        large enough for device operation.  The drivers MUST handle
        an unexpectedly large <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span>, but MAY check that <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span>
        is large enough for device operation.

The driver MUST NOT write into any field of the capability structure,
with the exception of those with <span class="hl kwa">\field</span><span class="hl opt">{</span>cap_type<span class="hl opt">}</span> VIRTIO_PCI_CAP_PCI_CFG as
detailed in <span class="hl kwa">\ref</span><span class="hl opt">{</span>drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability<span class="hl opt">}</span>.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Virtio Structure PCI Capabilities<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / Virtio Structure PCI Capabilities<span class="hl opt">}</span>

The device MUST include any extra data (from the beginning of the <span class="hl kwa">\field</span><span class="hl opt">{</span>cap_vndr<span class="hl opt">}</span> field
through end of the extra data fields if any) in <span class="hl kwa">\field</span><span class="hl opt">{</span>cap_len<span class="hl opt">}</span>.
The device MAY append extra data
or padding to any structure beyond that.

If the device presents multiple structures of the same type, it SHOULD order
them from optimal (first) to least-optimal (last).

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Common configuration structure layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout<span class="hl opt">}</span>

The common configuration structure is found at the <span class="hl kwa">\field</span><span class="hl opt">{</span>bar<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}</span> within the VIRTIO_PCI_CAP_COMMON_CFG capability; its layout is below.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_pci_common_cfg <span class="hl opt">{</span>
        /* About the whole device. */
        le32 device_feature_select;     /* read-write */
        le32 device_feature;            /* read-only for driver */
        le32 driver_feature_select;     /* read-write */
        le32 driver_feature;            /* read-write */
        le16 msix_config;               /* read-write */
        le16 num_queues;                /* read-only for driver */
        u8 device_status;               /* read-write */
        u8 config_generation;           /* read-only for driver */

        /* About a specific virtqueue. */
        le16 queue_select;              /* read-write */
        le16 queue_size;                /* read-write, power of <span class="hl num">2</span>, or <span class="hl num">0</span>. */
        le16 queue_msix_vector;         /* read-write */
        le16 queue_enable;              /* read-write */
        le16 queue_notify_off;          /* read-only for driver */
        le64 queue_desc;                /* read-write */
        le64 queue_avail;               /* read-write */
        le64 queue_used;                /* read-write */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature_select<span class="hl opt">}]</span>
        The driver uses this to select which feature bits <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature<span class="hl opt">}</span> shows.
        Value <span class="hl num">0x0</span> selects Feature Bits <span class="hl num">0</span> to <span class="hl num">31</span>, <span class="hl num">0x1</span> selects Feature Bits <span class="hl num">32</span> to <span class="hl num">63</span>, etc.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature<span class="hl opt">}]</span>
        The device uses this to <span class="hl kwb">report</span> which feature bits it is
        offering to the driver: the driver writes to
        <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature_select<span class="hl opt">}</span> to select which feature bits are presented.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature_select<span class="hl opt">}]</span>
        The driver uses this to select which feature bits <span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature<span class="hl opt">}</span> shows.
        Value <span class="hl num">0x0</span> selects Feature Bits <span class="hl num">0</span> to <span class="hl num">31</span>, <span class="hl num">0x1</span> selects Feature Bits <span class="hl num">32</span> to <span class="hl num">63</span>, etc.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature<span class="hl opt">}]</span>
        The driver writes this to accept feature bits offered by the device.
        Driver Feature Bits selected by <span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature_select<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}]</span>
        The driver sets the Configuration Vector for MSI-X.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>num_queues<span class="hl opt">}]</span>
        The device specifies the maximum number of virtqueues supported here.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>device_status<span class="hl opt">}]</span>
        The driver writes the device status here (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Status Field<span class="hl opt">}</span>). Writing <span class="hl num">0</span> into this
        field resets the device.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}]</span>
        Configuration atomicity value.  The device changes this every time the
        configuration noticeably changes.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_select<span class="hl opt">}]</span>
        Queue Select. The driver selects which virtqueue the following
        fields refer to.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}]</span>
        Queue Size.  On reset, specifies the maximum queue size supported by
        the hypervisor. This can be modified by driver to reduce memory requirements.
        A <span class="hl num">0</span> means the queue is unavailable.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}]</span>
        The driver uses this to specify the queue vector for MSI-X.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_enable<span class="hl opt">}]</span>
        The driver uses this to selectively prevent the device from executing requests from this virtqueue.
        <span class="hl num">1</span> - enabled; <span class="hl num">0</span> - disabled.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_notify_off<span class="hl opt">}]</span>
        The driver reads this to calculate the offset from start of Notification structure at
        which this virtqueue is located.
        <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span> this is <span class="hl kwa">\em</span><span class="hl opt">{</span>not<span class="hl opt">}</span> an offset in bytes.
        See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Notification capability<span class="hl opt">}</span> below.
        <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_desc<span class="hl opt">}]</span>
        The driver writes the physical address of Descriptor Table here.  See section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_avail<span class="hl opt">}]</span>
        The driver writes the physical address of Available Ring here.  See section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>queue_used<span class="hl opt">}]</span>
        The driver writes the physical address of Used Ring here.  See section <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Common configuration structure layout<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout<span class="hl opt">}</span>
<span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}</span> MUST be <span class="hl num">4</span>-byte aligned.

The device MUST present at least one common configuration capability.

The device MUST present the feature bits it is offering in <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature<span class="hl opt">}</span>, starting at bit <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature_select<span class="hl opt">}</span> $*$ <span class="hl num">32</span> for any <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature_select<span class="hl opt">}</span> written by the driver.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  This means that it will present <span class="hl num">0</span> for any <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature_select<span class="hl opt">}</span> other than <span class="hl num">0</span> or <span class="hl num">1</span>, since no feature defined here exceeds <span class="hl num">63</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

The device MUST present any valid feature bits the driver has written in <span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature<span class="hl opt">}</span>, starting at bit <span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature_select<span class="hl opt">}</span> $*$ <span class="hl num">32</span> for any <span class="hl kwa">\field</span><span class="hl opt">{</span>driver_feature_select<span class="hl opt">}</span> written by the driver.  Valid feature bits are those which are subset of the corresponding <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature<span class="hl opt">}</span> bits.  The device MAY present invalid bits written by the driver.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  This means that a device can ignore writes for feature bits it never
  offers, and simply present <span class="hl num">0</span> on reads.  Or it can just mirror what the driver wrote
  (but it will still have to check them when the driver sets FEATURES_OK).
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  A driver shouldn&apos;t write invalid bits anyway, as per <span class="hl kwa">\ref</span><span class="hl opt">{</span>drivernormative:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>, but this attempts to handle it.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

The device MUST present a changed <span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}</span> after the
driver has read a device-specific configuration value which has
changed since any part of the device-specific configuration was last
read.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
As <span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}</span> is an <span class="hl num">8</span>-bit value, simply incrementing it
on every configuration change could violate this requirement due to wrap.
Better would be to set an internal flag when it has changed,
and if that flag is set when the driver reads from the device-specific
configuration, increment <span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}</span> and clear the flag.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

The device MUST reset when <span class="hl num">0</span> is written to <span class="hl kwa">\field</span><span class="hl opt">{</span>device_status<span class="hl opt">}</span>, and
present a <span class="hl num">0</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>device_status<span class="hl opt">}</span> once that is done.

The device MUST present a <span class="hl num">0</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_enable<span class="hl opt">}</span> on reset.

The device MUST present a <span class="hl num">0</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}</span> if the virtqueue
corresponding to the current <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_select<span class="hl opt">}</span> is unavailable.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Common configuration structure layout<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout<span class="hl opt">}</span>

The driver MUST NOT write to <span class="hl kwa">\field</span><span class="hl opt">{</span>device_feature<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>num_queues<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}</span> or <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_notify_off<span class="hl opt">}</span>.

The driver MUST NOT write a value which is not a power of <span class="hl num">2</span> to <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}</span>.

The driver MUST configure the other virtqueue fields before enabling the virtqueue
with <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_enable<span class="hl opt">}</span>.

After writing <span class="hl num">0</span> to <span class="hl kwa">\field</span><span class="hl opt">{</span>device_status<span class="hl opt">}</span>, the driver MUST wait for a read of
<span class="hl kwa">\field</span><span class="hl opt">{</span>device_status<span class="hl opt">}</span> to return <span class="hl num">0</span> before reinitializing the device.

The driver MUST NOT write a <span class="hl num">0</span> to <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_enable<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notification structure layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Notification capability<span class="hl opt">}</span>

The notification location is found using the VIRTIO_PCI_CAP_NOTIFY_CFG
capability.  This capability is immediately followed by an additional
field, like so:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_pci_notify_cap <span class="hl opt">{</span>
        struct virtio_pci_cap cap;
        le32 notify_off_multiplier; /* Multiplier for queue_notify_off. */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>notify_off_multiplier<span class="hl opt">}</span> is combined with the <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_notify_off<span class="hl opt">}</span> to
derive the Queue Notify address within a BAR for a virtqueue:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
        cap.offset + queue_notify_off * notify_off_multiplier
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>notify_off_multiplier<span class="hl opt">}</span> are taken from the
notification capability structure above, and the <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_notify_off<span class="hl opt">}</span> is
taken from the common configuration structure.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, if <span class="hl kwa">\field</span><span class="hl opt">{</span>notifier_off_multiplier<span class="hl opt">}</span> is <span class="hl num">0</span>, the device uses
the same Queue Notify address for all queues.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Notification capability<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Notification capability<span class="hl opt">}</span>
The device MUST present at least one notification capability.

The <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span> MUST be <span class="hl num">2</span>-byte aligned.  

The device MUST either present <span class="hl kwa">\field</span><span class="hl opt">{</span>notify_off_multiplier<span class="hl opt">}</span> as an even power of <span class="hl num">2</span>,
or present <span class="hl kwa">\field</span><span class="hl opt">{</span>notify_off_multiplier<span class="hl opt">}</span> as <span class="hl num">0</span>.

The value <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span> presented by the device MUST be at least <span class="hl num">2</span>
and MUST be large enough to support queue notification offsets
for all supported queues in all possible configurations.

For all queues, the value <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span> presented by the device MUST satisfy:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
cap.length &gt;= queue_notify_off * notify_off_multiplier + <span class="hl num">2</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>ISR status capability<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / ISR status capability<span class="hl opt">}</span>

The VIRTIO_PCI_CAP_ISR_CFG capability
refers to at least a single byte, which contains the <span class="hl num">8</span>-bit ISR status field
to be used for INT\#x interrupt handling.

The <span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}</span> for the <span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> has no alignment requirements.

The ISR bits allow the device to distinguish between device-specific configuration
change interrupts and normal virtqueue interrupts:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span> |l||l|l|l| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Bits       &amp; <span class="hl num">0</span>                               &amp; <span class="hl num">1</span>               &amp;  <span class="hl num">2</span> to <span class="hl num">31</span> \\
<span class="hl kwa">\hline</span>
Purpose    &amp; Queue Interrupt  &amp; Device Configuration Interrupt &amp; Reserved \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

To avoid an extra access, simply reading this register resets it to <span class="hl num">0</span> and
causes the device to de-assert the interrupt.

In this way, driver read of ISR status causes the device to de-assert
an interrupt.

See sections <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Virtqueue Interrupts From The Device<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes<span class="hl opt">}</span> for how this is used.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>ISR status capability<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / ISR status capability<span class="hl opt">}</span>

The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG capability.  

The device MUST set the Device Configuration Interrupt bit
in <span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> before sending a device configuration
change notification to the driver.

If MSI-X capability is disabled, the device MUST set the Queue
Interrupt bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> before sending a virtqueue
notification to the driver.

If MSI-X capability is disabled, the device MUST set the Interrupt Status
bit in the PCI Status register in the PCI Configuration Header of
the device to the logical OR of all bits in <span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> of
the device.  The device then asserts/deasserts INT\#x interrupts unless masked
according to standard PCI rules <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:PCI<span class="hl opt">]{[</span>PCI<span class="hl opt">]}</span>.

The device MUST reset <span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> to <span class="hl num">0</span> on driver read.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>ISR status capability<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / ISR status capability<span class="hl opt">}</span>

If MSI-X capability is enabled, the driver SHOULD NOT access
<span class="hl kwa">\field</span><span class="hl opt">{</span>ISR status<span class="hl opt">}</span> upon detecting a Queue Interrupt.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device-specific configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Device-specific configuration<span class="hl opt">}</span>

The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG capability for
any device type which has a device-specific configuration.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device-specific configuration<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Device-specific configuration<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>offset<span class="hl opt">}</span> for the device-specific configuration MUST be <span class="hl num">4</span>-byte aligned.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>PCI configuration access capability<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability<span class="hl opt">}</span>

The VIRTIO_PCI_CAP_PCI_CFG capability
creates an alternative (and likely suboptimal) access method to the
common configuration, notification, ISR and device-specific configuration regions.

The capability is immediately followed by an additional field like so:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_pci_cfg_cap <span class="hl opt">{</span>
        struct virtio_pci_cap cap;
        u8 pci_cfg_data<span class="hl opt">[</span><span class="hl num">4</span><span class="hl opt">]</span>; /* Data for BAR access. */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The fields <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.bar<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span> and
<span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span> are read-write (RW) for the driver.

To access a device region, the driver writes into the capability
structure (ie. within the PCI configuration space) as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver sets the BAR to access by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.bar<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> The driver sets the size of the access by writing <span class="hl num">1</span>, <span class="hl num">2</span> or <span class="hl num">4</span> to
  <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> The driver sets the offset within the BAR by writing to
  <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

At that point, <span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span> will provide a window of size
<span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span> into the given <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.bar<span class="hl opt">}</span> at offset <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span>.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>PCI configuration access capability<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability<span class="hl opt">}</span>

The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG capability.

Upon detecting driver write access
to <span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span>, the device MUST execute a write access
at offset <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span> at BAR selected by <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.bar<span class="hl opt">}</span> using the first <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span>
bytes from <span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span>.

Upon detecting driver read access
to <span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span>, the device MUST
execute a read access of length cap.length at offset <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span>
at BAR selected by <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.bar<span class="hl opt">}</span> and store the first <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span> bytes in
<span class="hl kwa">\field</span><span class="hl opt">{</span>pci_cfg_data<span class="hl opt">}</span>.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>PCI configuration access capability<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability<span class="hl opt">}</span>

The driver MUST NOT write a <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.offset<span class="hl opt">}</span> which is not
a multiple of <span class="hl kwa">\field</span><span class="hl opt">{</span>cap.length<span class="hl opt">}</span> (ie. all accesses MUST be aligned).

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interfaces: A Note on PCI Device Layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Legacy Interfaces: A Note on PCI Device Layout<span class="hl opt">}</span>

Transitional devices MUST present part of configuration
registers in a legacy configuration structure in BAR0 in the first I/O
region of the PCI device, as documented below.
When using the legacy interface, transitional drivers
MUST use the legacy configuration structure in BAR0 in the first
I/O region of the PCI device, as documented below.

When using the legacy interface the driver MAY access
the device-specific configuration region using any width accesses, and
a transitional device MUST present driver with the same results as
when accessed using the ``natural&apos;&apos; access method (i.e.
<span class="hl num">32</span>-bit accesses for <span class="hl num">32</span>-bit fields, etc).

Note that this is possible because while the virtio common configuration structure is PCI
(i.e. little) endian, when using the legacy interface the device-specific
configuration region is encoded in the native endian of the guest (where such distinction is
applicable).

When used through the legacy interface, the virtio common configuration structure looks as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabularx<span class="hl opt">}{</span><span class="hl kwa">\textwidth</span><span class="hl opt">}{</span> |X||X|X|X|X|X|X|X|X| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
 Bits &amp; <span class="hl num">32</span> &amp; <span class="hl num">32</span> &amp; <span class="hl num">32</span> &amp; <span class="hl num">16</span> &amp; <span class="hl num">16</span> &amp; <span class="hl num">16</span> &amp; <span class="hl num">8</span> &amp; <span class="hl num">8</span> \\
<span class="hl kwa">\hline</span>
 Read / Write &amp; R &amp; R+W &amp; R+W &amp; R &amp; R+W &amp; R+W &amp; R+W &amp; R \\
<span class="hl kwa">\hline</span>
 Purpose &amp; Device Features bits <span class="hl num">0</span>:<span class="hl num">31</span> &amp; Driver Features bits <span class="hl num">0</span>:<span class="hl num">31</span> &amp;
  Queue Address &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}</span> &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_select<span class="hl opt">}</span> &amp; Queue Notify &amp;
  Device Status &amp; ISR <span class="hl kwa">\newline</span> Status \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabularx<span class="hl opt">}</span>

If MSI-X is enabled for the device, two additional fields
immediately follow this header:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span> |l||l|l| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Bits       &amp; <span class="hl num">16</span>             &amp; <span class="hl num">16</span>     \\
<span class="hl kwa">\hline</span>
Read/Write &amp; R+W            &amp; R+W    \\
<span class="hl kwa">\hline</span>
Purpose (MSI-X) &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span>  &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

Note: When MSI-X capability is enabled, device-specific configuration starts at
byte offset <span class="hl num">24</span> in virtio common configuration structure structure. When MSI-X capability is not
enabled, device-specific configuration starts at byte offset <span class="hl num">20</span> in virtio
header.  ie. once you enable MSI-X on the device, the other fields move.
If you turn it off again, they move back!

Any device-specific configuration space immediately follows
these general headers:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span>|l||l|l|<span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Bits &amp; Device Specific &amp; <span class="hl kwa">\multirow</span><span class="hl opt">{</span><span class="hl num">3</span><span class="hl opt">}{</span>*<span class="hl opt">}{</span><span class="hl kwa">\ldots</span><span class="hl opt">}</span> \\
<span class="hl kwa">\cline</span><span class="hl opt">{</span><span class="hl num">1</span>-<span class="hl num">2</span><span class="hl opt">}</span>
Read / Write &amp; Device Specific &amp; \\
<span class="hl kwa">\cline</span><span class="hl opt">{</span><span class="hl num">1</span>-<span class="hl num">2</span><span class="hl opt">}</span>
Purpose &amp; Device Specific &amp; \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

When accessing the device-specific configuration space
using the legacy interface, transitional
drivers MUST access the device-specific configuration space
at an offset immediately following the general headers.

When using the legacy interface, transitional
devices MUST present the device-specific configuration space
if any at an offset immediately following the general headers.

Note that only Feature Bits <span class="hl num">0</span> to <span class="hl num">31</span> are accessible through the
Legacy Interface. When used through the Legacy Interface,
Transitional Devices MUST assume that Feature Bits <span class="hl num">32</span> to <span class="hl num">63</span>
are not acknowledged by Driver.

As legacy devices had no <span class="hl kwa">\field</span><span class="hl opt">{</span>config_generation<span class="hl opt">}</span> field,
see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device
Configuration Space / Legacy Interface: Device Configuration
Space<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Configuration Space / Legacy Interface: Device Configuration Space<span class="hl opt">}</span> for workarounds.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Non-transitional Device With Legacy Driver: A Note
on PCI Device Layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio
Over PCI Bus / PCI Device Layout / Non-transitional Device With
Legacy Driver: A Note on PCI Device Layout<span class="hl opt">}</span>

Non-transitional devices, on a platform where a legacy driver for
a legacy device with the same ID might have previously existed,
SHOULD take the following steps to fail gracefully when a legacy
driver attempts to drive them:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Present an I/O BAR in BAR0, and
<span class="hl kwa">\item</span> Respond to a single-byte zero write to offset <span class="hl num">18</span>
   (corresponding to Device Status register in the legacy layout)
   of BAR0 by presenting zeroes on every BAR and ignoring writes.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>PCI-specific Initialization And Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>

This documents PCI-specific steps executed during Device Initialization.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Virtio Device Configuration Layout Detection<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtio Device Configuration Layout Detection<span class="hl opt">}</span>

As a prerequisite to device initialization, the driver scans the
PCI capability list, detecting virtio configuration layout using Virtio
Structure PCI capabilities as detailed in <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / Virtio Structure PCI Capabilities<span class="hl opt">}</span>

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Non-transitional Device With Legacy Driver<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Non-transitional Device With Legacy Driver<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Non-transitional Device With Legacy Driver<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Non-transitional Device With Legacy Driver<span class="hl opt">}</span>

Non-transitional devices, on a platform where a legacy driver for
a legacy device with the same ID might have previously existed,
MUST take the following steps to fail gracefully when a legacy
driver attempts to drive them:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Present an I/O BAR in BAR0, and
<span class="hl kwa">\item</span> Respond to a single-byte zero write to offset <span class="hl num">18</span>
   (corresponding to Device Status register in the legacy layout)
   of BAR0 by presenting zeroes on every BAR and ignoring writes.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: A Note on Device Layout Detection<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtio Device Configuration Layout Detection / Legacy Interface: A Note on Device Layout Detection<span class="hl opt">}</span>

Legacy drivers skipped the Device Layout Detection step, assuming legacy
device configuration space in BAR0 in I/O space unconditionally.

Legacy devices did not have the Virtio PCI Capability in their
capability list.

Therefore:

Transitional devices MUST expose the Legacy Interface in I/O
space in BAR0.

Transitional drivers MUST look for the Virtio PCI
Capabilities on the capability list.
If these are not present, driver MUST assume a legacy device,
and use it through the legacy interface.

Non-transitional drivers MUST look for the Virtio PCI
Capabilities on the capability list.
If these are not present, driver MUST assume a legacy device,
and fail gracefully.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>MSI-X Vector Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration<span class="hl opt">}</span>

When MSI-X capability is present and enabled in the device
(through standard PCI configuration space) <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> are used to map configuration change and queue
interrupts to MSI-X vectors. In this case, the ISR Status is unused.

Writing a valid MSI-X Table entry number, <span class="hl num">0</span> to <span class="hl num">0x7FF</span>, to
<span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> maps interrupts triggered
by the configuration change/selected queue events respectively to
the corresponding MSI-X vector. To disable interrupts for an
event type, the driver unmaps this event by writing a special NO_VECTOR
value:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
/* Vector value used to disable MSI for queue */
#define VIRTIO_MSI_NO_VECTOR            <span class="hl num">0xffff</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

Note that mapping an event to vector might require device to
allocate internal device resources, and thus could fail. 

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>MSI-X Vector Configuration<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration<span class="hl opt">}</span>

A device that has an MSI-X capability SHOULD support at least <span class="hl num">2</span>
and at most <span class="hl num">0x800</span> MSI-X vectors.
Device MUST <span class="hl kwb">report</span> the number of vectors supported in
<span class="hl kwa">\field</span><span class="hl opt">{</span>Table Size<span class="hl opt">}</span> in the MSI-X Capability as specified in
<span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:PCI<span class="hl opt">]{[</span>PCI<span class="hl opt">]}</span>.
The device SHOULD restrict the reported MSI-X Table Size field
to a value that might benefit system performance.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, a device which does not expect to send
interrupts at a high rate might only specify <span class="hl num">2</span> MSI-X vectors.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
Device MUST support mapping any event type to any valid
vector <span class="hl num">0</span> to MSI-X <span class="hl kwa">\field</span><span class="hl opt">{</span>Table Size<span class="hl opt">}</span>.
Device MUST support unmapping any event type.

The device MUST return vector mapped to a given event,
(NO_VECTOR if unmapped) on read of <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span>.
The device MUST have all queue and configuration change
events are unmapped upon reset.

Devices SHOULD NOT cause mapping an event to vector to fail
unless it is impossible for the device to satisfy the mapping
request.  Devices MUST <span class="hl kwb">report</span> mapping
failures by returning the NO_VECTOR value when the relevant
<span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> field is read. 

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>MSI-X Vector Configuration<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration<span class="hl opt">}</span>

Driver MUST support device with any MSI-X Table Size <span class="hl num">0</span> to <span class="hl num">0x7FF</span>.
Driver MAY fall back on using INT\#x interrupts for a device
which only supports one MSI-X vector (MSI-X Table Size = <span class="hl num">0</span>).

Driver MAY intepret the Table Size as a hint from the device
for the suggested number of MSI-X vectors to use.

Driver MUST NOT attempt to map an event to a vector
outside the MSI-X Table supported by the device,
as reported by <span class="hl kwa">\field</span><span class="hl opt">{</span>Table Size<span class="hl opt">}</span> in the MSI-X Capability.

After mapping an event to vector, the
driver MUST verify success by reading the Vector field value: on
success, the previously written value is returned, and on
failure, NO_VECTOR is returned. If a mapping failure is detected,
the driver MAY retry mapping with fewer vectors, disable MSI-X
or <span class="hl kwb">report</span> device failure.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Virtqueue Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration<span class="hl opt">}</span>

As a device can have zero or more virtqueues for bulk data
transport<span class="hl kwa">\footnote</span><span class="hl opt">{</span>For example, the simplest network device has two virtqueues.<span class="hl opt">}</span>, the driver
needs to configure them as part of the device-specific
configuration.

The driver typically does this as follows, for each virtqueue a device has:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Write the virtqueue index (first queue is <span class="hl num">0</span>) to <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_select<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Read the virtqueue size from <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}</span>. This controls how big the virtqueue is
  (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues<span class="hl opt">}</span>). If this field is <span class="hl num">0</span>, the virtqueue does not exist.

<span class="hl kwa">\item</span> Optionally, select a smaller virtqueue size and write it to <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_size<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Allocate and zero Descriptor Table, Available and Used rings for the
   virtqueue in contiguous physical memory.

<span class="hl kwa">\item</span> Optionally, if MSI-X capability is present and enabled on the
  device, select a vector to use to request interrupts triggered
  by virtqueue events. Write the MSI-X Table entry number
  corresponding to this vector into <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span>. Read
  <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span>: on success, previously written value is
  returned; on failure, NO_VECTOR value is returned.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: A Note on Virtqueue Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration / Legacy Interface: A Note on Virtqueue Configuration<span class="hl opt">}</span>
When using the legacy interface, the queue layout follows <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span> with an alignment of <span class="hl num">4096</span>.
Driver writes the physical address, divided
by <span class="hl num">4096</span> to the Queue Address field<span class="hl kwa">\footnote</span><span class="hl opt">{</span>The <span class="hl num">4096</span> is based on the x86 page size, but it&apos;s also large
enough to ensure that the separate parts of the virtqueue are on
separate cache lines.
<span class="hl opt">}</span>.  There was no mechanism to negotiate the queue size.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notifying The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notifying The Device<span class="hl opt">}</span>

The driver notifies the device by writing the <span class="hl num">16</span>-bit virtqueue index
of this virtqueue to the Queue Notify address.  See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Notification capability<span class="hl opt">}</span> for how to calculate this address.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Virtqueue Interrupts From The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Virtqueue Interrupts From The Device<span class="hl opt">}</span>

If an interrupt is necessary for a virtqueue, the device would typically act as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If MSI-X capability is disabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> Set the lower bit of the ISR Status field for the device.

    <span class="hl kwa">\item</span> Send the appropriate PCI interrupt for the device.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

  <span class="hl kwa">\item</span> If MSI-X capability is enabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> is not NO_VECTOR,
      request the appropriate MSI-X interrupt message for the
      device, <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> sets the MSI-X Table entry
      number.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Virtqueue Interrupts From The Device<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Virtqueue Interrupts From The Device<span class="hl opt">}</span>

If MSI-X capability is enabled and <span class="hl kwa">\field</span><span class="hl opt">{</span>queue_msix_vector<span class="hl opt">}</span> is
NO_VECTOR for a virtqueue, the device MUST NOT deliver an interrupt
for that virtqueue.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notification of Device Configuration Changes<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes<span class="hl opt">}</span>

Some virtio PCI devices can change the device configuration
state, as reflected in the device-specific configuration region of the device. In this case:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If MSI-X capability is disabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> Set the second lower bit of the ISR Status field for the device.

    <span class="hl kwa">\item</span> Send the appropriate PCI interrupt for the device.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

  <span class="hl kwa">\item</span> If MSI-X capability is enabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> If <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span> is not NO_VECTOR,
      request the appropriate MSI-X interrupt message for the
      device, <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span> sets the MSI-X Table entry
      number.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

A single interrupt MAY indicate both that one or more virtqueue has
been used and that the configuration space has changed.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Notification of Device Configuration Changes<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes<span class="hl opt">}</span>

If MSI-X capability is enabled and <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span> is
NO_VECTOR, the device MUST NOT deliver an interrupt
for device configuration space changes.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Notification of Device Configuration Changes<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes<span class="hl opt">}</span>

A driver MUST handle the case where the same interrupt is used to indicate
both device configuration space change and one or more virtqueues being used.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Driver Handling Interrupts<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Driver Handling Interrupts<span class="hl opt">}</span>
The driver interrupt handler would typically:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If MSI-X capability is disabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
      <span class="hl kwa">\item</span> Read the ISR Status field, which will reset it to zero.
      <span class="hl kwa">\item</span> If the lower bit is set:
        look through the used rings of all virtqueues for the
        device, to see if any progress has been made by the device
        which requires servicing.
      <span class="hl kwa">\item</span> If the second lower bit is set:
        re-examine the configuration space to see what changed.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> If MSI-X capability is enabled:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
      <span class="hl kwa">\item</span>
        Look through the used rings of
        all virtqueues mapped to that MSI-X vector for the
        device, to see if any progress has been made by the device
        which requires servicing.
      <span class="hl kwa">\item</span>
        If the MSI-X vector is equal to <span class="hl kwa">\field</span><span class="hl opt">{</span>config_msix_vector<span class="hl opt">}</span>,
        re-examine the configuration space to see what changed.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\section</span><span class="hl opt">{</span>Virtio Over MMIO<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO<span class="hl opt">}</span>

Virtual environments without PCI support (a common situation in
embedded devices models) might use simple memory mapped device
(``virtio-mmio&apos;&apos;) instead of the PCI device.

The memory mapped virtio device behaviour is based on the PCI
device specification. Therefore most operations including device
initialization, queues configuration and buffer transfers are
nearly identical. Existing differences are described in the
following sections.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>MMIO Device Discovery<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO Device Discovery<span class="hl opt">}</span>

Unlike PCI, MMIO provides no generic device discovery mechanism.  For each
device, the guest OS will need to know the location of the registers
and interrupt(s) used.  The suggested binding for systems using
flattened device trees is shown in this example:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
// EXAMPLE: virtio_block device taking <span class="hl num">512</span> bytes at <span class="hl num">0x1e000</span>, interrupt <span class="hl num">42</span>.
virtio_block&#64;<span class="hl num">1</span>e000 <span class="hl opt">{</span>
        compatible = &quot;virtio,mmio&quot;;
        reg = &lt;<span class="hl num">0x1e000 0x200</span>&gt;;
        interrupts = &lt;<span class="hl num">42</span>&gt;;
<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>MMIO Device Register Layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>

MMIO virtio devices provide a set of memory mapped control
registers followed by a device-specific configuration space,
described in the table~<span class="hl kwa">\ref</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>.

All register values are organized as Little Endian.

<span class="hl kwa">\newcommand</span><span class="hl opt">{</span><span class="hl kwa">\mmioreg</span><span class="hl opt">}[</span><span class="hl num">5</span><span class="hl opt">]{</span><span class="hl slc">% Name Function Offset Direction Description</span>
  <span class="hl opt">{</span><span class="hl kwa">\field</span><span class="hl opt">{</span><span class="hl kwc">#1</span><span class="hl opt">}}</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#3</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#4</span> &amp; <span class="hl opt">{</span><span class="hl kwa">\bf</span><span class="hl kwc">#2</span><span class="hl opt">}</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#5</span> \\
<span class="hl opt">}</span>

<span class="hl kwa">\newcommand</span><span class="hl opt">{</span><span class="hl kwa">\mmiodreg</span><span class="hl opt">}[</span><span class="hl num">7</span><span class="hl opt">]{</span><span class="hl slc">% NameHigh NameLow Function OffsetHigh OffsetLow Direction Description</span>
  <span class="hl opt">{</span><span class="hl kwa">\field</span><span class="hl opt">{</span><span class="hl kwc">#1</span><span class="hl opt">}}</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#4</span> <span class="hl kwa">\newline</span> <span class="hl opt">{</span><span class="hl kwa">\field</span><span class="hl opt">{</span><span class="hl kwc">#2</span><span class="hl opt">}}</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#5</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#6</span> &amp; <span class="hl opt">{</span><span class="hl kwa">\bf</span><span class="hl kwc">#3</span><span class="hl opt">}</span> <span class="hl kwa">\newline</span> <span class="hl kwc">#7</span> \\
<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>longtable<span class="hl opt">}{</span>p<span class="hl opt">{</span><span class="hl num">0.2</span><span class="hl kwa">\textwidth</span><span class="hl opt">}</span>p<span class="hl opt">{</span><span class="hl num">0.7</span><span class="hl kwa">\textwidth</span><span class="hl opt">}}</span>
  <span class="hl kwa">\caption</span> <span class="hl opt">{</span>MMIO Device Register Layout<span class="hl opt">}</span>
  <span class="hl kwa">\label</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span> \\
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Name<span class="hl opt">}{</span>Function<span class="hl opt">}{</span>Offset from base<span class="hl opt">}{</span>Direction<span class="hl opt">}{</span>Description<span class="hl opt">}</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\endfirsthead</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Name<span class="hl opt">}{</span>Function<span class="hl opt">}{</span>Offset from the base<span class="hl opt">}{</span>Direction<span class="hl opt">}{</span>Description<span class="hl opt">}</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\endhead</span>
  <span class="hl kwa">\endfoot</span>
  <span class="hl kwa">\endlastfoot</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>MagicValue<span class="hl opt">}{</span>Magic value<span class="hl opt">}{</span><span class="hl num">0x000</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    <span class="hl num">0x74726976</span>
    (a Little Endian equivalent of the ``virt&apos;&apos; string).
  <span class="hl opt">}</span> 
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Version<span class="hl opt">}{</span>Device version number<span class="hl opt">}{</span><span class="hl num">0x004</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    <span class="hl num">0x2</span>.
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
      Legacy devices (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / Legacy interface<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / Legacy interface<span class="hl opt">}</span>) used <span class="hl num">0x1</span>.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DeviceID<span class="hl opt">}{</span>Virtio Subsystem Device ID<span class="hl opt">}{</span><span class="hl num">0x008</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span> for possible values.
    Value zero (<span class="hl num">0x0</span>) is used to
    define a system memory map with placeholder devices at static,
    well known addresses, assigning functions to them depending
    on user&apos;s needs.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>VendorID<span class="hl opt">}{</span>Virtio Subsystem Vendor ID<span class="hl opt">}{</span><span class="hl num">0x00c</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DeviceFeatures<span class="hl opt">}{</span>Flags representing features the device supports<span class="hl opt">}{</span><span class="hl num">0x010</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from this register returns <span class="hl num">32</span> consecutive flag bits,
    the least significant bit depending on the last value written to
    <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span>. Access to this register returns
    bits $<span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span>*<span class="hl num">32</span>$ to $(<span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span>*<span class="hl num">32</span>)+<span class="hl num">31</span>$, eg.
    feature bits <span class="hl num">0</span> to <span class="hl num">31</span> if <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span> is set to <span class="hl num">0</span> and
    features bits <span class="hl num">32</span> to <span class="hl num">63</span> if <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span> is set to <span class="hl num">1</span>.
    Also see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}{</span>Device (host) features word selection.<span class="hl opt">}{</span><span class="hl num">0x014</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register selects a set of <span class="hl num">32</span> device feature bits
    accessible by reading from <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeatures<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DriverFeatures<span class="hl opt">}{</span>Flags representing device features understood and activated by the driver<span class="hl opt">}{</span><span class="hl num">0x020</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register sets <span class="hl num">32</span> consecutive flag bits, the least significant
    bit depending on the last value written to <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span>.
     Access to this register sets bits $<span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span>*<span class="hl num">32</span>$
    to $(<span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span>*<span class="hl num">32</span>)+<span class="hl num">31</span>$, eg. feature bits <span class="hl num">0</span> to <span class="hl num">31</span> if
    <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span> is set to <span class="hl num">0</span> and features bits <span class="hl num">32</span> to <span class="hl num">63</span> if
    <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span> is set to <span class="hl num">1</span>. Also see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}{</span>Activated (guest) features word selection<span class="hl opt">}{</span><span class="hl num">0x024</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register selects a set of <span class="hl num">32</span> activated feature
    bits accessible by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeatures<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}{</span>Virtual queue index<span class="hl opt">}{</span><span class="hl num">0x030</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register selects the virtual queue that the
    following operations on <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span>,
    <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescLow<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescHigh<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailLow<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailHigh<span class="hl opt">}</span>,
    <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedLow<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedHigh<span class="hl opt">}</span> apply to. The index
    number of the first queue is zero (<span class="hl num">0x0</span>). 
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}{</span>Maximum virtual queue size<span class="hl opt">}{</span><span class="hl num">0x034</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from the register returns the maximum size (number of
    elements) of the queue the device is ready to process or
    zero (<span class="hl num">0x0</span>) if the queue is not available. This applies to the
    queue selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}{</span>Virtual queue size<span class="hl opt">}{</span><span class="hl num">0x038</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Queue size is the number of elements in the queue, therefore in each
    of the Descriptor Table, the Available Ring and the Used Ring.
    Writing to this register notifies the device what size of the
    queue the driver will use. This applies to the queue selected by
    writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}{</span>Virtual queue ready bit<span class="hl opt">}{</span><span class="hl num">0x044</span><span class="hl opt">}{</span>RW<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing one (<span class="hl num">0x1</span>) to this register notifies the device that it can
    execute requests from this virtual queue. Reading from this register
    returns the last value written to it. Both read and write
    accesses apply to the queue selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNotify<span class="hl opt">}{</span>Queue notifier<span class="hl opt">}{</span><span class="hl num">0x050</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing a queue index to this register notifies the device that
    there are new buffers to process in the queue.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}{</span>Interrupt status<span class="hl opt">}{</span><span class="hl num">0x60</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from this register returns a bit mask of events that
    caused the device interrupt to be asserted.
    The following events are possible:
    <span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
      <span class="hl kwa">\item</span><span class="hl opt">[</span>Used Ring Update<span class="hl opt">]</span> - bit <span class="hl num">0</span> - the interrupt was asserted
        because the device has updated the Used
        Ring in at least one of the active virtual queues.
      <span class="hl kwa">\item</span> <span class="hl opt">[</span>Configuration Change<span class="hl opt">]</span> - bit <span class="hl num">1</span> - the interrupt was
        asserted because the configuration of the device has changed.
    <span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>InterruptACK<span class="hl opt">}{</span>Interrupt acknowledge<span class="hl opt">}{</span><span class="hl num">0x064</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing a value with bits set as defined in <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span>
    to this register notifies the device that events causing
    the interrupt have been handled.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Status<span class="hl opt">}{</span>Device status<span class="hl opt">}{</span><span class="hl num">0x070</span><span class="hl opt">}{</span>RW<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from this register returns the current device status
    flags.
    Writing non-zero values to this register sets the status flags,
    indicating the driver progress. Writing zero (<span class="hl num">0x0</span>) to this
    register triggers a device reset. 
    See also p. <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmiodreg</span><span class="hl opt">{</span>QueueDescLow<span class="hl opt">}{</span>QueueDescHigh<span class="hl opt">}{</span>Virtual queue&apos;s Descriptor Table <span class="hl num">64</span> bit long physical address<span class="hl opt">}{</span><span class="hl num">0x080</span><span class="hl opt">}{</span><span class="hl num">0x084</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to these two registers (lower <span class="hl num">32</span> bits of the address
    to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescLow<span class="hl opt">}</span>, higher <span class="hl num">32</span> bits to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescHigh<span class="hl opt">}</span>) notifies
    the device about location of the Descriptor Table of the queue
    selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span> register.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmiodreg</span><span class="hl opt">{</span>QueueAvailLow<span class="hl opt">}{</span>QueueAvailHigh<span class="hl opt">}{</span>Virtual queue&apos;s Available Ring <span class="hl num">64</span> bit long physical address<span class="hl opt">}{</span><span class="hl num">0x090</span><span class="hl opt">}{</span><span class="hl num">0x094</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to these two registers (lower <span class="hl num">32</span> bits of the address
    to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailLow<span class="hl opt">}</span>, higher <span class="hl num">32</span> bits to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailHigh<span class="hl opt">}</span>) notifies
    the device about location of the Available Ring of the queue
    selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmiodreg</span><span class="hl opt">{</span>QueueUsedLow<span class="hl opt">}{</span>QueueUsedHigh<span class="hl opt">}{</span>Virtual queue&apos;s Used Ring <span class="hl num">64</span> bit long physical address<span class="hl opt">}{</span><span class="hl num">0x0a0</span><span class="hl opt">}{</span><span class="hl num">0x0a4</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to these two registers (lower <span class="hl num">32</span> bits of the address
    to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedLow<span class="hl opt">}</span>, higher <span class="hl num">32</span> bits to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedHigh<span class="hl opt">}</span>) notifies
    the device about location of the Used Ring of the queue
    selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>ConfigGeneration<span class="hl opt">}{</span>Configuration atomicity value<span class="hl opt">}{</span><span class="hl num">0x0fc</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span>
    Reading from this register returns a value describing a version of the device-specific configuration space (see <span class="hl kwa">\field</span><span class="hl opt">{</span>Config<span class="hl opt">}</span>).
    The driver can then access the configuration space and, when finished, read <span class="hl kwa">\field</span><span class="hl opt">{</span>ConfigGeneration<span class="hl opt">}</span> again.
    If no part of the configuration space has changed between these two <span class="hl kwa">\field</span><span class="hl opt">{</span>ConfigGeneration<span class="hl opt">}</span> reads, the returned values are identical.
    If the values are different, the configuration space accesses were not atomic and the driver has to perform the operations again.
    See also <span class="hl kwa">\ref</span> <span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Device Configuration Space<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Config<span class="hl opt">}{</span>Configuration space<span class="hl opt">}{</span><span class="hl num">0x100</span>+<span class="hl opt">}{</span>RW<span class="hl opt">}{</span>
    Device-specific configuration space starts at the offset <span class="hl num">0x100</span>
    and is accessed with byte alignment. Its meaning and size
    depend on the device and the driver.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>longtable<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>MMIO Device Register Layout<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>

The device MUST return <span class="hl num">0x74726976</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>MagicValue<span class="hl opt">}</span>.

The device MUST return value <span class="hl num">0x2</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>Version<span class="hl opt">}</span>.

The device MUST present each event by setting the corresponding bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span> from the
moment it takes place, until the driver acknowledges the interrupt
by writing a corresponding bit mask to the <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptACK<span class="hl opt">}</span> register.  Bits which
do not represent events which took place MUST be zero.

Upon reset, the device MUST clear all bits in <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span> and ready bits in the
<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span> register for all queues in the device.

The device MUST change value returned in <span class="hl kwa">\field</span><span class="hl opt">{</span>ConfigGeneration<span class="hl opt">}</span> if there is any risk of a
driver seeing an inconsistent configuration state.

The device MUST NOT access virtual queue contents when <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span> is zero (<span class="hl num">0x0</span>).

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>MMIO Device Register Layout<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>
The driver MUST NOT access memory locations not described in the
table <span class="hl kwa">\ref</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>
(or, in case of the configuration space, described in the device specification),
MUST NOT write to the read-only registers (direction R) and
MUST NOT read from the write-only registers (direction W).

The driver MUST only use <span class="hl num">32</span> bit wide and aligned reads and writes to access the control registers
described in table <span class="hl kwa">\ref</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Register Layout<span class="hl opt">}</span>.
For the device-specific configuration space, the driver MUST use <span class="hl num">8</span> bit wide accesses for
<span class="hl num">8</span> bit wide fields, <span class="hl num">16</span> bit wide and aligned accesses for <span class="hl num">16</span> bit wide fields and <span class="hl num">32</span> bit wide and
aligned accesses for <span class="hl num">32</span> and <span class="hl num">64</span> bit wide fields.

The driver MUST ignore a device with <span class="hl kwa">\field</span><span class="hl opt">{</span>MagicValue<span class="hl opt">}</span> which is not <span class="hl num">0x74726976</span>,
although it MAY <span class="hl kwb">report</span> an error.

The driver MUST ignore a device with <span class="hl kwa">\field</span><span class="hl opt">{</span>Version<span class="hl opt">}</span> which is not <span class="hl num">0x2</span>,
although it MAY <span class="hl kwb">report</span> an error.

The driver MUST ignore a device with <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceID<span class="hl opt">}</span> <span class="hl num">0x0</span>,
but MUST NOT <span class="hl kwb">report</span> any error.

Before reading from <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeatures<span class="hl opt">}</span>, the driver MUST write a value to <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceFeaturesSel<span class="hl opt">}</span>.

Before writing to the <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeatures<span class="hl opt">}</span> register, the driver MUST write a value to the <span class="hl kwa">\field</span><span class="hl opt">{</span>DriverFeaturesSel<span class="hl opt">}</span> register.

The driver MUST write a value to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span> which is less than
or equal to the value presented by the device in <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>.

When <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span> is not zero, the driver MUST NOT access
<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescLow<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescHigh<span class="hl opt">}</span>,
<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailLow<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailHigh<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedLow<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedHigh<span class="hl opt">}</span>.

To stop using the queue the driver MUST write zero (<span class="hl num">0x0</span>) to this
<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span> and MUST read the value back to ensure
synchronization.

The driver MUST ignore undefined bits in <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span>.

The driver MUST write a value with a bit mask describing events it handled into <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptACK<span class="hl opt">}</span> when
it finishes handling an interrupt and MUST NOT set any of the undefined bits in the value.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>MMIO-specific Initialization And Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device Initialization<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>

The driver MUST start the device initialization by reading and
checking values from <span class="hl kwa">\field</span><span class="hl opt">{</span>MagicValue<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>Version<span class="hl opt">}</span>.
If both values are valid, it MUST read <span class="hl kwa">\field</span><span class="hl opt">{</span>DeviceID<span class="hl opt">}</span>
and if its value is zero (<span class="hl num">0x0</span>) MUST abort initialization and
MUST NOT access any other register.

Further initialization MUST follow the procedure described in
<span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Virtqueue Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Virtqueue Configuration<span class="hl opt">}</span>

The driver will typically initialize the virtual queue in the following way:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Select the queue writing its index (first queue is <span class="hl num">0</span>) to
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Check if the queue is not already in use: read <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span>,
   and expect a returned value of zero (<span class="hl num">0x0</span>).

<span class="hl kwa">\item</span> Read maximum queue size (number of elements) from
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>. If the returned value is zero (<span class="hl num">0x0</span>) the
   queue is not available.

<span class="hl kwa">\item</span> Allocate and zero the queue pages, making sure the memory
   is physically contiguous. It is recommended to align the
   Used Ring to an optimal boundary (usually the page size).

<span class="hl kwa">\item</span> Notify the device about the queue size by writing the size to
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Write physical addresses of the queue&apos;s Descriptor Table,
   Available Ring and Used Ring to (respectively) the
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescLow<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueDescHigh<span class="hl opt">}</span>,
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailLow<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAvailHigh<span class="hl opt">}</span> and
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedLow<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>QueueUsedHigh<span class="hl opt">}</span> register pairs.

<span class="hl kwa">\item</span> Write <span class="hl num">0x1</span> to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueReady<span class="hl opt">}</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notifying The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Notifying The Device<span class="hl opt">}</span>

The driver notifies the device about new buffers being available in
a queue by writing the index of the updated queue to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNotify<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Notifications From The Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Notifications From The Device<span class="hl opt">}</span>

The memory mapped virtio device is using a single, dedicated
interrupt signal, which is asserted when at least one of the
bits described in the description of <span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span>
is set. This is how the device notifies the
driver about a new used buffer being available in the queue
or about a change in the device configuration.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Notifications From The Device<span class="hl opt">}{</span>Virtio Transport Options / Virtio Over MMIO / MMIO-specific Initialization And Device Operation / Notifications From The Device<span class="hl opt">}</span>
After receiving an interrupt, the driver MUST read
<span class="hl kwa">\field</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}</span> to check what caused the interrupt
(see the register description). After the interrupt is handled,
the driver MUST acknowledge it by writing a bit mask
corresponding to the handled events to the InterruptACK register.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Legacy interface<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over MMIO / Legacy interface<span class="hl opt">}</span>

The legacy MMIO transport used page-based addressing, resulting
in a slightly different control register layout, the device
initialization and the virtual queue configuration procedure.

Table <span class="hl kwa">\ref</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Legacy Register Layout<span class="hl opt">}</span> 
presents control registers layout, omitting
descriptions of registers which did not change their function
nor behaviour:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>longtable<span class="hl opt">}{</span>p<span class="hl opt">{</span><span class="hl num">0.2</span><span class="hl kwa">\textwidth</span><span class="hl opt">}</span>p<span class="hl opt">{</span><span class="hl num">0.7</span><span class="hl kwa">\textwidth</span><span class="hl opt">}}</span>
  <span class="hl kwa">\caption</span> <span class="hl opt">{</span>MMIO Device Legacy Register Layout<span class="hl opt">}</span>
  <span class="hl kwa">\label</span><span class="hl opt">{</span>tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device Legacy Register Layout<span class="hl opt">}</span> \\
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Name<span class="hl opt">}{</span>Function<span class="hl opt">}{</span>Offset from base<span class="hl opt">}{</span>Direction<span class="hl opt">}{</span>Description<span class="hl opt">}</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\endfirsthead</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Name<span class="hl opt">}{</span>Function<span class="hl opt">}{</span>Offset from the base<span class="hl opt">}{</span>Direction<span class="hl opt">}{</span>Description<span class="hl opt">}</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\endhead</span>
  <span class="hl kwa">\endfoot</span>
  <span class="hl kwa">\endlastfoot</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>MagicValue<span class="hl opt">}{</span>Magic value<span class="hl opt">}{</span><span class="hl num">0x000</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Version<span class="hl opt">}{</span>Device version number<span class="hl opt">}{</span><span class="hl num">0x004</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span>Legacy device returns value <span class="hl num">0x1</span>.<span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>DeviceID<span class="hl opt">}{</span>Virtio Subsystem Device ID<span class="hl opt">}{</span><span class="hl num">0x008</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>VendorID<span class="hl opt">}{</span>Virtio Subsystem Vendor ID<span class="hl opt">}{</span><span class="hl num">0x00c</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>HostFeatures<span class="hl opt">}{</span>Flags representing features the device supports<span class="hl opt">}{</span><span class="hl num">0x010</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>HostFeaturesSel<span class="hl opt">}{</span>Device (host) features word selection.<span class="hl opt">}{</span><span class="hl num">0x014</span><span class="hl opt">}{</span>W<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>GuestFeatures<span class="hl opt">}{</span>Flags representing device features understood and activated by the driver<span class="hl opt">}{</span><span class="hl num">0x020</span><span class="hl opt">}{</span>W<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>GuestFeaturesSel<span class="hl opt">}{</span>Activated (guest) features word selection<span class="hl opt">}{</span><span class="hl num">0x024</span><span class="hl opt">}{</span>W<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span> 
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>GuestPageSize<span class="hl opt">}{</span>Guest page size<span class="hl opt">}{</span><span class="hl num">0x028</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    The driver writes the guest page size in bytes to the
    register during initialization, before any queues are used.
    This value should be a power of <span class="hl num">2</span> and is used by the device to
    calculate the Guest address of the first queue page
    (see QueuePFN).
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}{</span>Virtual queue index<span class="hl opt">}{</span><span class="hl num">0x030</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register selects the virtual queue that the
    following operations on the <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAlign<span class="hl opt">}</span>
    and <span class="hl kwa">\field</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}</span> registers apply to. The index
    number of the first queue is zero (<span class="hl num">0x0</span>). 
.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}{</span>Maximum virtual queue size<span class="hl opt">}{</span><span class="hl num">0x034</span><span class="hl opt">}{</span>R<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from the register returns the maximum size of the queue
    the device is ready to process or zero (<span class="hl num">0x0</span>) if the queue is not
    available. This applies to the queue selected by writing to
    <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span> and is allowed only when <span class="hl kwa">\field</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}</span> is set to zero
    (<span class="hl num">0x0</span>), so when the queue is not actively used.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}{</span>Virtual queue size<span class="hl opt">}{</span><span class="hl num">0x038</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Queue size is the number of elements in the queue, therefore size
    of the descriptor table and both available and used rings.
    Writing to this register notifies the device what size of the
    queue the driver will use. This applies to the queue selected by
    writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueAlign<span class="hl opt">}{</span>Used Ring alignment in the virtual queue<span class="hl opt">}{</span><span class="hl num">0x03c</span><span class="hl opt">}{</span>W<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register notifies the device about alignment
    boundary of the Used Ring in bytes. This value should be a power
    of <span class="hl num">2</span> and applies to the queue selected by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}{</span>Guest physical page number of the virtual queue<span class="hl opt">}{</span><span class="hl num">0x040</span><span class="hl opt">}{</span>RW<span class="hl opt">}{</span><span class="hl slc">%</span>
    Writing to this register notifies the device about location of the
    virtual queue in the Guest&apos;s physical address space. This value
    is the index number of a page starting with the queue
    Descriptor Table. Value zero (<span class="hl num">0x0</span>) means physical address zero
    (<span class="hl num">0x00000000</span>) and is illegal. When the driver stops using the
    queue it writes zero (<span class="hl num">0x0</span>) to this register.
    Reading from this register returns the currently used page
    number of the queue, therefore a value other than zero (<span class="hl num">0x0</span>)
    means that the queue is in use.
    Both read and write accesses apply to the queue selected by
    writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>QueueNotify<span class="hl opt">}{</span>Queue notifier<span class="hl opt">}{</span><span class="hl num">0x050</span><span class="hl opt">}{</span>W<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>InterruptStatus<span class="hl opt">}{</span>Interrupt status<span class="hl opt">}{</span><span class="hl num">0x60</span><span class="hl opt">}{</span>R<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>InterruptACK<span class="hl opt">}{</span>Interrupt acknowledge<span class="hl opt">}{</span><span class="hl num">0x064</span><span class="hl opt">}{</span>W<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Status<span class="hl opt">}{</span>Device status<span class="hl opt">}{</span><span class="hl num">0x070</span><span class="hl opt">}{</span>RW<span class="hl opt">}{</span><span class="hl slc">%</span>
    Reading from this register returns the current device status
    flags.
    Writing non-zero values to this register sets the status flags,
    indicating the OS/driver progress. Writing zero (<span class="hl num">0x0</span>) to this
    register triggers a device reset. The device
    sets <span class="hl kwa">\field</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}</span> to zero (<span class="hl num">0x0</span>) for all queues in the device.
    Also see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Initialization<span class="hl opt">}</span>.
  <span class="hl opt">}</span>
  <span class="hl kwa">\hline</span>
  <span class="hl kwa">\mmioreg</span><span class="hl opt">{</span>Config<span class="hl opt">}{</span>Configuration space<span class="hl opt">}{</span><span class="hl num">0x100</span>+<span class="hl opt">}{</span>RW<span class="hl opt">}{}</span>
  <span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>longtable<span class="hl opt">}</span>

The virtual queue page size is defined by writing to <span class="hl kwa">\field</span><span class="hl opt">{</span>GuestPageSize<span class="hl opt">}</span>,
as written by the guest. The driver does this before the
virtual queues are configured.

The virtual queue layout follows
p. <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>,
with the alignment defined in <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAlign<span class="hl opt">}</span>.

The virtual queue is configured as follows:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Select the queue writing its index (first queue is <span class="hl num">0</span>) to
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueSel<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Check if the queue is not already in use: read <span class="hl kwa">\field</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}</span>,
   expecting a returned value of zero (<span class="hl num">0x0</span>).

<span class="hl kwa">\item</span> Read maximum queue size (number of elements) from
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>. If the returned value is zero (<span class="hl num">0x0</span>) the
   queue is not available.

<span class="hl kwa">\item</span> Allocate and zero the queue pages in contiguous virtual
   memory, aligning the Used Ring to an optimal boundary (usually
   page size). The driver should choose a queue size smaller than or
   equal to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNumMax<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Notify the device about the queue size by writing the size to
   <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueNum<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Notify the device about the used alignment by writing its value
   in bytes to <span class="hl kwa">\field</span><span class="hl opt">{</span>QueueAlign<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Write the physical number of the first page of the queue to
   the <span class="hl kwa">\field</span><span class="hl opt">{</span>QueuePFN<span class="hl opt">}</span> register.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

Notification mechanisms did not change.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Virtio Over Channel I/O<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio Over Channel I/O<span class="hl opt">}</span>

S/<span class="hl num">390</span> based virtual machines support neither PCI nor MMIO, so a
different transport is needed there.

virtio-ccw uses the standard channel I/O based mechanism used for
the majority of devices on S/<span class="hl num">390</span>. A virtual channel device with a
special control unit type acts as proxy to the virtio device
(similar to the way virtio-pci uses a PCI device) and
configuration and operation of the virtio device is accomplished
(mostly) via channel commands. This means virtio devices are
discoverable via standard operating system algorithms, and adding
virtio support is mainly a question of supporting a new control
unit type.

As the S/<span class="hl num">390</span> is a big endian machine, the data structures transmitted
via channel commands are big-endian: this is made clear by use of
the types be16, be32 and be64.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Basic Concepts<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Basic Concepts<span class="hl opt">}</span>

As a proxy device, virtio-ccw uses a channel-attached I/O control
unit with a special control unit type (<span class="hl num">0x3832</span>) and a control unit
model corresponding to the attached virtio device&apos;s subsystem
device ID, accessed via a virtual I/O subchannel and a virtual
channel path of type <span class="hl num">0x32</span>. This proxy device is discoverable via
normal channel subsystem device discovery (usually a STORE
SUBCHANNEL loop) and answers to the basic channel commands:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> NO-OPERATION (<span class="hl num">0x03</span>)
<span class="hl kwa">\item</span> BASIC SENSE (<span class="hl num">0x04</span>)
<span class="hl kwa">\item</span> TRANSFER IN CHANNEL (<span class="hl num">0x08</span>)
<span class="hl kwa">\item</span> SENSE ID (<span class="hl num">0xe4</span>)
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

For a virtio-ccw proxy device, SENSE ID will return the following
information:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span> |l|l|l| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Bytes &amp; Description &amp; Contents \\
<span class="hl kwa">\hline \hline</span>
<span class="hl num">0</span>     &amp; reserved              &amp; <span class="hl num">0xff</span> \\
<span class="hl kwa">\hline</span>
<span class="hl num">1</span>-<span class="hl num">2</span>   &amp; control unit type     &amp; <span class="hl num">0x3832</span> \\
<span class="hl kwa">\hline</span>
<span class="hl num">3</span>     &amp; control unit model    &amp; &lt;virtio device id&gt; \\
<span class="hl kwa">\hline</span>
<span class="hl num">4</span>-<span class="hl num">5</span>   &amp; device type           &amp; zeroes (unset) \\
<span class="hl kwa">\hline</span>
<span class="hl num">6</span>     &amp; device model          &amp; zeroes (unset) \\
<span class="hl kwa">\hline</span>
<span class="hl num">7</span>-<span class="hl num">255</span> &amp; extended SenseId data &amp; zeroes (unset) \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

In addition to the basic channel commands, virtio-ccw defines a
set of channel commands related to configuration and operation of
virtio:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define CCW_CMD_SET_VQ <span class="hl num">0x13</span>
#define CCW_CMD_VDEV_RESET <span class="hl num">0x33</span>
#define CCW_CMD_SET_IND <span class="hl num">0x43</span>
#define CCW_CMD_SET_CONF_IND <span class="hl num">0x53</span>
#define CCW_CMD_SET_IND_ADAPTER <span class="hl num">0x73</span>
#define CCW_CMD_READ_FEAT <span class="hl num">0x12</span>
#define CCW_CMD_WRITE_FEAT <span class="hl num">0x11</span>
#define CCW_CMD_READ_CONF <span class="hl num">0x22</span>
#define CCW_CMD_WRITE_CONF <span class="hl num">0x21</span>
#define CCW_CMD_WRITE_STATUS <span class="hl num">0x31</span>
#define CCW_CMD_READ_VQ_CONF <span class="hl num">0x32</span>
#define CCW_CMD_SET_VIRTIO_REV <span class="hl num">0x83</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Basic Concepts<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Basic Concepts<span class="hl opt">}</span>

The virtio-ccw device acts like a normal channel device, as specified
in <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:S390 PoP<span class="hl opt">]{[</span>S390 PoP<span class="hl opt">]}</span> and <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:S390 Common I/O<span class="hl opt">]{[</span>S390 Common I/O<span class="hl opt">]}</span>. In particular:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> A device MUST post a unit check with command reject for any command
  it does not support.

<span class="hl kwa">\item</span> If a driver did not suppress length checks for a channel command,
  the device MUST present a subchannel status as detailed in the
  architecture when the actual length did not match the expected length.

<span class="hl kwa">\item</span> If a driver did suppress length checks for a channel command, the
  device MUST present a check condition if the transmitted data does
  not contain enough data to process the command. If the driver submitted
  a buffer that was too long, the device SHOULD accept the command.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Basic Concepts<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Basic Concepts<span class="hl opt">}</span>

A driver for virtio-ccw devices MUST check for a control unit
type of <span class="hl num">0x3832</span> and MUST ignore the device type and model.

A driver SHOULD attempt to provide the correct length in a channel
command even if it suppresses length checks for that command.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization<span class="hl opt">}</span>

virtio-ccw uses several channel commands to set up a device.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Setting the Virtio Revision<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision<span class="hl opt">}</span>

CCW_CMD_SET_VIRTIO_REV is issued by the driver to set the revision of
the virtio-ccw transport it intends to drive the device with. It uses the
following communication structure:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_rev_info <span class="hl opt">{</span>
        be16 revision;
        be16 length;
        u8 data<span class="hl opt">[]</span>;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>revision<span class="hl opt">}</span> contains the desired revision id, <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span> the length of the
data portion and <span class="hl kwa">\field</span><span class="hl opt">{</span>data<span class="hl opt">}</span> revision-dependent additional desired options.

The following values are supported:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span> |l|l|l|l| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
<span class="hl kwa">\field</span><span class="hl opt">{</span>revision<span class="hl opt">}</span> &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span> &amp; <span class="hl kwa">\field</span><span class="hl opt">{</span>data<span class="hl opt">}</span>      &amp; remarks \\
<span class="hl kwa">\hline \hline</span>
<span class="hl num">0</span>        &amp; <span class="hl num">0</span>      &amp; &lt;empty&gt;   &amp; legacy interface; transitional devices only \\
<span class="hl kwa">\hline</span>
<span class="hl num">1</span>        &amp; <span class="hl num">0</span>      &amp; &lt;empty&gt;   &amp; Virtio <span class="hl num">1.0</span> \\
<span class="hl kwa">\hline</span>
<span class="hl num">2</span>-n      &amp;        &amp;           &amp; reserved for later revisions \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

Note that a change in the virtio standard does not necessarily
correspond to a change in the virtio-ccw revision.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Setting the Virtio Revision<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision<span class="hl opt">}</span>

A device MUST post a unit check with command reject for any <span class="hl kwa">\field</span><span class="hl opt">{</span>revision<span class="hl opt">}</span>
it does not support. For any invalid combination of <span class="hl kwa">\field</span><span class="hl opt">{</span>revision<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>length<span class="hl opt">}</span>
and <span class="hl kwa">\field</span><span class="hl opt">{</span>data<span class="hl opt">}</span>, it MUST post a unit check with command reject as well. A
non-transitional device MUST reject revision id <span class="hl num">0</span>.

A device MUST answer with command reject to any virtio-ccw specific
channel command that is not contained in the revision selected by the
driver.

A device MUST answer with command reject to any attempt to select a different revision
after a revision has been successfully selected by the driver.

A device MUST treat the revision as unset from the time the associated
subchannel has been enabled until a revision has been successfully set
by the driver. This implies that revisions are not persistent across
disabling and enabling of the associated subchannel.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Setting the Virtio Revision<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision<span class="hl opt">}</span>

A driver SHOULD start with trying to set the highest revision it
supports and continue with lower revisions if it gets a command reject.

A driver MUST NOT issue any other virtio-ccw specific channel commands
prior to setting the revision.

After a revision has been successfully selected by the driver, it
MUST NOT attempt to select a different revision.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interfaces: A Note on Setting the Virtio Revision<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision / Legacy Interfaces: A Note on Setting the Virtio Revision<span class="hl opt">}</span>

A legacy device will not support the CCW_CMD_SET_VIRTIO_REV and answer
with a command reject. A non-transitional driver MUST stop trying to
operate this device in that case. A transitional driver MUST operate
the device as if it had been able to set revision <span class="hl num">0</span>.

A legacy driver will not issue the CCW_CMD_SET_VIRTIO_REV prior to
issuing other virtio-ccw specific channel commands. A non-transitional
device therefore MUST answer any such attempts with a command reject.
A transitional device MUST assume in this case that the driver is a
legacy driver and continue as if the driver selected revision <span class="hl num">0</span>. This
implies that the device MUST reject any command not valid for revision
<span class="hl num">0</span>, including a subsequent CCW_CMD_SET_VIRTIO_REV.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Configuring a Virtqueue<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue<span class="hl opt">}</span>

CCW_CMD_READ_VQ_CONF is issued by the driver to obtain information
about a queue. It uses the following structure for communicating:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct vq_config_block <span class="hl opt">{</span>
        be16 index;
        be16 max_num;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The requested number of buffers for queue <span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span> is returned in
<span class="hl kwa">\field</span><span class="hl opt">{</span>max_num<span class="hl opt">}</span>.

Afterwards, CCW_CMD_SET_VQ is issued by the driver to inform the
device about the location used for its queue. The transmitted
structure is

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct vq_info_block <span class="hl opt">{</span>
        be64 desc;
        be32 res0;
        be16 index;
        be16 num;
        be64 avail;
        be64 used;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>desc<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>avail<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>used<span class="hl opt">}</span> contain the guest addresses for the descriptor table,
available ring and used ring for queue <span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span>, respectively. The actual
virtqueue size (number of allocated buffers) is transmitted in <span class="hl kwa">\field</span><span class="hl opt">{</span>num<span class="hl opt">}</span>.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Configuring a Virtqueue<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>res0<span class="hl opt">}</span> is reserved and MUST be ignored by the device.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interface: A Note on Configuring a Virtqueue<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue / Legacy Interface: A Note on Configuring a Virtqueue<span class="hl opt">}</span>

For a legacy driver or for a driver that selected revision <span class="hl num">0</span>,
CCW_CMD_SET_VQ uses the following communication block:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct vq_info_block_legacy <span class="hl opt">{</span>
        be64 queue;
        be32 align;
        be16 index;
        be16 num;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>queue<span class="hl opt">}</span> contains the guest address for queue <span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>num<span class="hl opt">}</span> the number of buffers
and <span class="hl kwa">\field</span><span class="hl opt">{</span>align<span class="hl opt">}</span> the alignment. The queue layout follows <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Communicating Status Information<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information<span class="hl opt">}</span>

The driver changes the status of a device via the
CCW_CMD_WRITE_STATUS command, which transmits an <span class="hl num">8</span> bit status
value.

As described in
<span class="hl kwa">\ref</span><span class="hl opt">{</span>devicenormative:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>,
a device sometimes fails to set the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> field: For example, it
might fail to accept the FEATURES_OK status bit during device initialization.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Communicating Status Information<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information<span class="hl opt">}</span>

If the device posts a unit check with command reject in response to the
CCW_CMD_WRITE_STATUS command, the driver MUST assume that the device failed
to set the status and the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> field retained its previous value.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Communicating Status Information<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information<span class="hl opt">}</span>

If the device fails to set the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> field to the value written by
the driver, the device MUST assure that the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> field is left
unchanged and MUST post a unit check with command reject.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Handling Device Features<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Handling Device Features<span class="hl opt">}</span>

Feature bits are arranged in an array of <span class="hl num">32</span> bit values, making
for a total of <span class="hl num">8192</span> feature bits. Feature bits are in
little-endian byte order.

The CCW commands dealing with features use the following
communication block:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_feature_desc <span class="hl opt">{</span>
        le32 features;
        u8 index;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>features<span class="hl opt">}</span> are the <span class="hl num">32</span> bits of features currently accessed, while
<span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span> describes which of the feature bit values is to be
accessed. No padding is added at the end of the structure, it is
exactly <span class="hl num">5</span> bytes in length.

The guest obtains the device&apos;s device feature set via the
CCW_CMD_READ_FEAT command. The device stores the features at <span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span>
to <span class="hl kwa">\field</span><span class="hl opt">{</span>features<span class="hl opt">}</span>.

For communicating its supported features to the device, the driver
uses the CCW_CMD_WRITE_FEAT command, denoting a <span class="hl kwa">\field</span><span class="hl opt">{</span>features<span class="hl opt">}</span>/<span class="hl kwa">\field</span><span class="hl opt">{</span>index<span class="hl opt">}</span>
combination.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Device Configuration<span class="hl opt">}</span>

The device&apos;s configuration space is located in host memory.

To obtain information from the configuration space, the driver
uses CCW_CMD_READ_CONF, specifying the guest memory for the device
to write to.

For changing configuration information, the driver uses
CCW_CMD_WRITE_CONF, specifying the guest memory for the device to
read from.

In both cases, the complete configuration space is transmitted.  This
allows the driver to compare the new configuration space with the old
version, and keep a generation count internally whenever it changes.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Setting Up Indicators<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators<span class="hl opt">}</span>

In order to set up the indicator bits for host-&gt;guest notification,
the driver uses different channel commands depending on whether it
wishes to use traditional I/O interrupts tied to a subchannel or
adapter I/O interrupts for virtqueue notifications. For any given
device, the two mechanisms are mutually exclusive.

For the configuration change indicators, only a mechanism using
traditional I/O interrupts is provided, regardless of whether
traditional or adapter I/O interrupts are used for virtqueue
notifications.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Setting Up Classic Queue Indicators<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Classic Queue Indicators<span class="hl opt">}</span>

Indicators for notification via classic I/O interrupts are contained
in a <span class="hl num">64</span> bit value per virtio-ccw proxy device.

To communicate the location of the indicator bits for host-&gt;guest
notification, the driver uses the CCW_CMD_SET_IND command,
pointing to a location containing the guest address of the
indicators in a <span class="hl num">64</span> bit value.

If the driver has already set up two-staged queue indicators via the
CCW_CMD_SET_IND_ADAPTER command, the device MUST post a unit check
with command reject to any subsequent CCW_CMD_SET_IND command.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Setting Up Configuration Change Indicators<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Configuration Change Indicators<span class="hl opt">}</span>

Indicators for configuration change host-&gt;guest notification are
contained in a <span class="hl num">64</span> bit value per virtio-ccw proxy device.

To communicate the location of the indicator bits used in the
configuration change host-&gt;guest notification, the driver issues the
CCW_CMD_SET_CONF_IND command, pointing to a location containing the
guest address of the indicators in a <span class="hl num">64</span> bit value.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Setting Up Two-Stage Queue Indicators<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Two-Stage Queue Indicators<span class="hl opt">}</span>

Indicators for notification via adapter I/O interrupts consist of
two stages:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> a summary indicator byte covering the virtqueues for one or more
  virtio-ccw proxy devices
<span class="hl kwa">\item</span> a set of contigous indicator bits for the virtqueues for a
  virtio-ccw proxy device
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

To communicate the location of the summary and queue indicator bits,
the driver uses the CCW_CMD_SET_IND_ADAPTER command with the following
payload:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_thinint_area <span class="hl opt">{</span>
        be64 summary_indicator;
        be64 indicator;
        be64 bit_nr;
        u8 isc;
<span class="hl opt">}</span> __attribute__ ((packed));
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>summary_indicator<span class="hl opt">}</span> contains the guest address of the <span class="hl num">8</span> bit summary
indicator.
<span class="hl kwa">\field</span><span class="hl opt">{</span>indicator<span class="hl opt">}</span> contains the guest address of an area wherein the indicators
for the devices are contained, starting at <span class="hl kwa">\field</span><span class="hl opt">{</span>bit_nr<span class="hl opt">}</span>, one bit per
virtqueue of the device. Bit numbers start at the left, i.e. the most
significant bit in the first byte is assigned the bit number <span class="hl num">0</span>.
<span class="hl kwa">\field</span><span class="hl opt">{</span>isc<span class="hl opt">}</span> contains the I/O interruption subclass to be used for the adapter
I/O interrupt. It MAY be different from the isc used by the proxy
virtio-ccw device&apos;s subchannel.
No padding is added at the end of the structure, it is exactly <span class="hl num">25</span> bytes
in length.


<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Setting Up Two-Stage Queue Indicators<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Two-Stage Queue Indicators<span class="hl opt">}</span>
If the driver has already set up classic queue indicators via the
CCW_CMD_SET_IND command, the device MUST post a unit check with
command reject to any subsequent CCW_CMD_SET_IND_ADAPTER command.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interfaces: A Note on Setting Up Indicators<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Legacy Interfaces: A Note on Setting Up Indicators<span class="hl opt">}</span>

In some cases, legacy devices will only support classic queue indicators;
in that case, they will reject CCW_CMD_SET_IND_ADAPTER as they don&apos;t know that
command. Some legacy devices will support two-stage queue indicators, though,
and a driver will be able to successfully use CCW_CMD_SET_IND_ADAPTER to set
them up.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Host-&gt;Guest Notification<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification<span class="hl opt">}</span>

There are two modes of operation regarding host-&gt;guest notification,
classic I/O interrupts and adapter I/O interrupts. The mode to be
used is determined by the driver by using CCW_CMD_SET_IND respectively
CCW_CMD_SET_IND_ADAPTER to set up queue indicators.

For configuration changes, the driver always uses classic I/O
interrupts.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Notification via Classic I/O Interrupts<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification / Notification via Classic I/O Interrupts<span class="hl opt">}</span>

If the driver used the CCW_CMD_SET_IND command to set up queue
indicators, the device will use classic I/O interrupts for
host-&gt;guest notification about virtqueue activity.

For notifying the driver of virtqueue buffers, the device sets the
corresponding bit in the guest-provided indicators. If an
interrupt is not already pending for the subchannel, the device
generates an unsolicited I/O interrupt.

If the device wants to notify the driver about configuration
changes, it sets bit <span class="hl num">0</span> in the configuration indicators and
generates an unsolicited I/O interrupt, if needed. This also
applies if adapter I/O interrupts are used for queue notifications.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Notification via Adapter I/O Interrupts<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification / Notification via Adapter I/O Interrupts<span class="hl opt">}</span>

If the driver used the CCW_CMD_SET_IND_ADAPTER command to set up
queue indicators, the device will use adapter I/O interrupts for
host-&gt;guest notification about virtqueue activity.

For notifying the driver of virtqueue buffers, the device sets the
bit in the guest-provided indicator area at the corresponding offset.
The guest-provided summary indicator is set to <span class="hl num">0x01</span>. An adapter I/O
interrupt for the corresponding interruption subclass is generated.

The recommended way to process an adapter I/O interrupt by the driver
is as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Process all queue indicator bits associated with the summary indicator.
<span class="hl kwa">\item</span> Clear the summary indicator, performing a synchronization (memory
barrier) afterwards.
<span class="hl kwa">\item</span> Process all queue indicator bits associated with the summary indicator
again.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Notification via Adapter I/O Interrupts<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification / Notification via Adapter I/O Interrupts<span class="hl opt">}</span>

The device SHOULD only generate an adapter I/O interrupt if the
summary indicator had not been set prior to notification.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Notification via Adapter I/O Interrupts<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification / Notification via Adapter I/O Interrupts<span class="hl opt">}</span>
The driver
MUST clear the summary indicator after receiving an adapter I/O
interrupt before it processes the queue indicators.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interfaces: A Note on Host-&gt;Guest Notification<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host-&gt;Guest Notification / Legacy Interfaces: A Note on Host-&gt;Guest Notification<span class="hl opt">}</span>

As legacy devices and drivers support only classic queue indicators,
host-&gt;guest notification will always be done via classic I/O interrupts.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Guest-&gt;Host Notification<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest-&gt;Host Notification<span class="hl opt">}</span>

For notifying the device of virtqueue buffers, the driver
unfortunately can&apos;t use a channel command (the asynchronous
characteristics of channel I/O interact badly with the host block
I/O backend). Instead, it uses a diagnose <span class="hl num">0x500</span> call with subcode
<span class="hl num">3</span> specifying the queue, as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">}{</span> |l|l|l| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
GPR  &amp;   Input Value     &amp; Output Value \\
<span class="hl kwa">\hline \hline</span>
  <span class="hl num">1</span>   &amp;       <span class="hl num">0x3</span>         &amp;              \\
<span class="hl kwa">\hline</span>
  <span class="hl num">2</span>   &amp;  Subchannel ID    &amp; Host Cookie  \\
<span class="hl kwa">\hline</span>
  <span class="hl num">3</span>   &amp; Virtqueue number  &amp;              \\
<span class="hl kwa">\hline</span>
  <span class="hl num">4</span>   &amp;   Host Cookie     &amp;              \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Guest-&gt;Host Notification<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest-&gt;Host Notification<span class="hl opt">}</span>
The device MUST ignore bits <span class="hl num">0</span>-<span class="hl num">31</span> (counting from the left) of GPR2.
This aligns passing the subchannel ID with the way it is passed
for the existing I/O instructions.

The device MAY return a <span class="hl num">64</span>-bit host cookie in GPR2 to speed up the
notification execution.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Guest-&gt;Host Notification<span class="hl opt">}{</span>Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest-&gt;Host Notification<span class="hl opt">}</span>

For each notification, the driver SHOULD use GPR4 to pass the host cookie received in GPR2 from the previous notication.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
info-&gt;cookie = do_notify(schid,
                         virtqueue_get_queue_index(vq),
                         info-&gt;cookie);
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Resetting Devices<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices<span class="hl opt">}</span>

In order to reset a device, a driver sends the
CCW_CMD_VDEV_RESET command.


<span class="hl kwa">\chapter</span><span class="hl opt">{</span>Device Types<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types<span class="hl opt">}</span>

On top of the queues, config space and feature negotiation facilities
built into virtio, several devices are defined.

The following device IDs are used to identify different types of virtio
devices.  Some device IDs are reserved for devices which are not currently
defined in this standard.

Discovering what devices are available and their type is bus-dependent.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>tabular<span class="hl opt">} {</span> |l|c| <span class="hl opt">}</span>
<span class="hl kwa">\hline</span>
Device ID  &amp;  Virtio Device    \\
<span class="hl kwa">\hline \hline</span>
<span class="hl num">0</span>          &amp; reserved (invalid) \\
<span class="hl kwa">\hline</span>
<span class="hl num">1</span>          &amp;   network card     \\
<span class="hl kwa">\hline</span>
<span class="hl num">2</span>          &amp;   block device     \\
<span class="hl kwa">\hline</span>
<span class="hl num">3</span>          &amp;      console       \\
<span class="hl kwa">\hline</span>
<span class="hl num">4</span>          &amp;  entropy source    \\
<span class="hl kwa">\hline</span>
<span class="hl num">5</span>          &amp; memory ballooning (legacy)  \\
<span class="hl kwa">\hline</span>
<span class="hl num">6</span>          &amp;     ioMemory       \\
<span class="hl kwa">\hline</span>
<span class="hl num">7</span>          &amp;       rpmsg        \\
<span class="hl kwa">\hline</span>
<span class="hl num">8</span>          &amp;     SCSI host      \\
<span class="hl kwa">\hline</span>
<span class="hl num">9</span>          &amp;   <span class="hl num">9</span>P transport     \\
<span class="hl kwa">\hline</span>
<span class="hl num">10</span>         &amp;   mac80211 wlan    \\
<span class="hl kwa">\hline</span>
<span class="hl num">11</span>         &amp;   rproc serial     \\
<span class="hl kwa">\hline</span>
<span class="hl num">12</span>         &amp;   virtio CAIF      \\
<span class="hl kwa">\hline</span>
<span class="hl num">13</span>         &amp;  memory balloon    \\
<span class="hl kwa">\hline</span>
<span class="hl num">16</span>         &amp;   GPU device       \\
<span class="hl kwa">\hline</span>
<span class="hl num">17</span>         &amp;   Timer/Clock device \\
<span class="hl kwa">\hline</span>
<span class="hl num">18</span>         &amp;   Input device \\
<span class="hl kwa">\hline</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>tabular<span class="hl opt">}</span>

Some of the devices above are unspecified by this <span class="hl kwb">document</span>,
because they are seen as immature or especially niche.  Be warned
that some are only specified by the sole existing implementation;
they could become part of a future specification, be abandoned
entirely, or live on outside this standard.  We shall speak of
them no further.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Network Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device<span class="hl opt">}</span>

The virtio network device is a virtual ethernet card, and is the
most complex of the devices supported so far by virtio. It has
enhanced rapidly and demonstrates clearly how support for new
features are added to an existing device. Empty buffers are
placed in one virtqueue for receiving packets, and outgoing
packets are enqueued into another for transmission in that order.
A third command queue is used to control advanced filtering
features.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device ID<span class="hl opt">}</span>

 <span class="hl num">1</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Virtqueues<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> receiveq1
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">1</span><span class="hl opt">]</span> transmitq1
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\ldots</span><span class="hl opt">]</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span>N<span class="hl opt">]</span> receiveqN
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span>N+<span class="hl num">1</span><span class="hl opt">]</span> transmitqN
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span>N+<span class="hl num">2</span><span class="hl opt">]</span> controlq
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

 N=<span class="hl num">1</span> if VIRTIO_NET_F_MQ is not negotiated, otherwise N is set by
 <span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span>.

 controlq only exists if VIRTIO_NET_F_CTRL_VQ set.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Feature bits<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CSUM (<span class="hl num">0</span>)<span class="hl opt">]</span> Device handles packets with partial checksum.   This 
  ``checksum offload&apos;&apos; is a common feature on modern network cards.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_CSUM (<span class="hl num">1</span>)<span class="hl opt">]</span> Driver handles packets with partial checksum.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_GUEST_OFFLOADS (<span class="hl num">2</span>)<span class="hl opt">]</span> Control channel offloads
        reconfiguration support.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_MAC (<span class="hl num">5</span>)<span class="hl opt">]</span> Device has given MAC address.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_TSO4 (<span class="hl num">7</span>)<span class="hl opt">]</span> Driver can receive TSOv4.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_TSO6 (<span class="hl num">8</span>)<span class="hl opt">]</span> Driver can receive TSOv6.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_ECN (<span class="hl num">9</span>)<span class="hl opt">]</span> Driver can receive TSO with ECN.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_UFO (<span class="hl num">10</span>)<span class="hl opt">]</span> Driver can receive UFO.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_TSO4 (<span class="hl num">11</span>)<span class="hl opt">]</span> Device can receive TSOv4.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_TSO6 (<span class="hl num">12</span>)<span class="hl opt">]</span> Device can receive TSOv6.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_ECN (<span class="hl num">13</span>)<span class="hl opt">]</span> Device can receive TSO with ECN.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_UFO (<span class="hl num">14</span>)<span class="hl opt">]</span> Device can receive UFO.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_MRG_RXBUF (<span class="hl num">15</span>)<span class="hl opt">]</span> Driver can merge receive buffers.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_STATUS (<span class="hl num">16</span>)<span class="hl opt">]</span> Configuration status field is
    available.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_VQ (<span class="hl num">17</span>)<span class="hl opt">]</span> Control channel is available.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_RX (<span class="hl num">18</span>)<span class="hl opt">]</span> Control channel RX mode support.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_VLAN (<span class="hl num">19</span>)<span class="hl opt">]</span> Control channel VLAN filtering.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_ANNOUNCE(<span class="hl num">21</span>)<span class="hl opt">]</span> Driver can send gratuitous
    packets.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_MQ(<span class="hl num">22</span>)<span class="hl opt">]</span> Device supports multiqueue with automatic
    receive steering.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_MAC_ADDR(<span class="hl num">23</span>)<span class="hl opt">]</span> Set MAC address through control
    channel.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Feature bit requirements<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Feature bits / Feature bit requirements<span class="hl opt">}</span>

Some networking feature bits require other networking feature bits
(see <span class="hl kwa">\ref</span><span class="hl opt">{</span>drivernormative:Basic Facilities of a Virtio Device / Feature Bits<span class="hl opt">}</span>):

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_TSO4<span class="hl opt">]</span> Requires VIRTIO_NET_F_GUEST_CSUM.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_TSO6<span class="hl opt">]</span> Requires VIRTIO_NET_F_GUEST_CSUM.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_ECN<span class="hl opt">]</span> Requires VIRTIO_NET_F_GUEST_TSO4 or VIRTIO_NET_F_GUEST_TSO6.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_UFO<span class="hl opt">]</span> Requires VIRTIO_NET_F_GUEST_CSUM.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_TSO4<span class="hl opt">]</span> Requires VIRTIO_NET_F_CSUM.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_TSO6<span class="hl opt">]</span> Requires VIRTIO_NET_F_CSUM.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_ECN<span class="hl opt">]</span> Requires VIRTIO_NET_F_HOST_TSO4 or VIRTIO_NET_F_HOST_TSO6.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_HOST_UFO<span class="hl opt">]</span> Requires VIRTIO_NET_F_CSUM.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_RX<span class="hl opt">]</span> Requires VIRTIO_NET_F_CTRL_VQ.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_VLAN<span class="hl opt">]</span> Requires VIRTIO_NET_F_CTRL_VQ.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GUEST_ANNOUNCE<span class="hl opt">]</span> Requires VIRTIO_NET_F_CTRL_VQ.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_MQ<span class="hl opt">]</span> Requires VIRTIO_NET_F_CTRL_VQ.
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_CTRL_MAC_ADDR<span class="hl opt">]</span> Requires VIRTIO_NET_F_CTRL_VQ.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_NET_F_GSO (<span class="hl num">6</span>)<span class="hl opt">]</span> Device handles packets with any GSO type.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

This was supposed to indicate segmentation offload support, but
upon further investigation it became clear that multiple bits
were needed.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device configuration layout<span class="hl opt">}</span>
<span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Feature bits / Device configuration layout<span class="hl opt">}</span>

Three driver-read-only configuration fields are currently defined. The <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> address field
always exists (though is only valid if VIRTIO_NET_F_MAC is set), and
<span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> only exists if VIRTIO_NET_F_STATUS is set. Two
read-only bits (for the driver) are currently defined for the status field:
VIRTIO_NET_S_LINK_UP and VIRTIO_NET_S_ANNOUNCE.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_NET_S_LINK_UP     <span class="hl num">1</span>
#define VIRTIO_NET_S_ANNOUNCE    <span class="hl num">2</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The following driver-read-only field, <span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span> only exists if
VIRTIO_NET_F_MQ is set. This field specifies the maximum number
of each of transmit and receive virtqueues (receiveq1<span class="hl kwa">\ldots</span> receiveqN
and transmitq1<span class="hl kwa">\ldots</span> transmitqN respectively) that can be configured once VIRTIO_NET_F_MQ
is negotiated.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_net_config <span class="hl opt">{</span>
        u8 mac<span class="hl opt">[</span><span class="hl num">6</span><span class="hl opt">]</span>;
        le16 status;
        le16 max_virtqueue_pairs;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device configuration layout<span class="hl opt">}{</span>Device Types / Network Device / Device configuration layout<span class="hl opt">}</span>

The device MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span> to between <span class="hl num">1</span> and <span class="hl num">0x8000</span> inclusive,
if it offers VIRTIO_NET_F_MQ.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device configuration layout<span class="hl opt">}{</span>Device Types / Network Device / Device configuration layout<span class="hl opt">}</span>

A driver SHOULD negotiate VIRTIO_NET_F_MAC if the device offers it.
If the driver negotiates the VIRTIO_NET_F_MAC feature, the driver MUST set
the physical address of the NIC to <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span>.  Otherwise, it SHOULD
use a locally-administered MAC address (see <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:IEEE <span class="hl num">802</span><span class="hl opt">]{</span>IEEE <span class="hl num">802</span><span class="hl opt">}</span>,
``<span class="hl num">9.2 48</span>-bit universal LAN MAC addresses&apos;&apos;).

If the driver does not negotiate the VIRTIO_NET_F_STATUS feature, it SHOULD
assume the link is active, otherwise it SHOULD read the link status from
the bottom bit of <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device configuration layout / Legacy Interface: Device configuration layout<span class="hl opt">}</span>
<span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Feature bits / Device configuration layout / Legacy Interface: Device configuration layout<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> and
<span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span> in struct virtio_net_config
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

When using the legacy interface, <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> is driver-writable
which provided a way for drivers to update the MAC without
negotiating VIRTIO_NET_F_CTRL_MAC_ADDR.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Initialization<span class="hl opt">}</span>

A driver would perform a typical initialization routine like so:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Identify and initialize the receive and
  transmission virtqueues, up to N of each kind. If
  VIRTIO_NET_F_MQ feature bit is negotiated,
  N=<span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span>, otherwise identify N=<span class="hl num">1</span>.

<span class="hl kwa">\item</span> If the VIRTIO_NET_F_CTRL_VQ feature bit is negotiated,
  identify the control virtqueue.

<span class="hl kwa">\item</span> Fill the receive queues with buffers: see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> Even with VIRTIO_NET_F_MQ, only receiveq1, transmitq1 and
  controlq are used by default.  The driver would send the
  VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command specifying the
  number of the transmit and receive queues to use.

<span class="hl kwa">\item</span> If the VIRTIO_NET_F_MAC feature bit is set, the configuration
  space <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> entry indicates the ``physical&apos;&apos; address of the
  network card, otherwise the driver would typically generate a random
  local MAC address.

<span class="hl kwa">\item</span> If the VIRTIO_NET_F_STATUS feature bit is negotiated, the link
  status comes from the bottom bit of <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>.
  Otherwise, the driver assumes it&apos;s active.

<span class="hl kwa">\item</span> A performant driver would indicate that it will generate checksumless
  packets by negotating the VIRTIO_NET_F_CSUM feature.

<span class="hl kwa">\item</span> If that feature is negotiated, a driver can use TCP or UDP
  segmentation offload by negotiating the VIRTIO_NET_F_HOST_TSO4 (IPv4
  TCP), VIRTIO_NET_F_HOST_TSO6 (IPv6 TCP) and VIRTIO_NET_F_HOST_UFO
  (UDP fragmentation) features.

<span class="hl kwa">\item</span> The converse features are also available: a driver can save
  the virtual device some work by negotiating these features.<span class="hl kwa">\note</span><span class="hl opt">{</span>For example, a network packet transported between two guests on
the same system might not need checksumming at all, nor segmentation,
if both guests are amenable.<span class="hl opt">}</span>
   The VIRTIO_NET_F_GUEST_CSUM feature indicates that partially
  checksummed packets can be received, and if it can do that then
  the VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
  VIRTIO_NET_F_GUEST_UFO and VIRTIO_NET_F_GUEST_ECN are the input
  equivalents of the features described above.
  See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Processing of Packets<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Processing of Packets<span class="hl opt">}</span> below.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

A truly minimal driver would only accept VIRTIO_NET_F_MAC and ignore
everything else.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation<span class="hl opt">}</span>

Packets are transmitted by placing them in the
transmitq1<span class="hl kwa">\ldots</span> transmitqN, and buffers for incoming packets are
placed in the receiveq1<span class="hl kwa">\ldots</span> receiveqN. In each case, the packet
itself is preceded by a header:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_net_hdr <span class="hl opt">{</span>
#define VIRTIO_NET_HDR_F_NEEDS_CSUM    <span class="hl num">1</span>
        u8 flags;
#define VIRTIO_NET_HDR_GSO_NONE        <span class="hl num">0</span>
#define VIRTIO_NET_HDR_GSO_TCPV4       <span class="hl num">1</span>
#define VIRTIO_NET_HDR_GSO_UDP         <span class="hl num">3</span>
#define VIRTIO_NET_HDR_GSO_TCPV6       <span class="hl num">4</span>
#define VIRTIO_NET_HDR_GSO_ECN      <span class="hl num">0x80</span>
        u8 gso_type;
        le16 hdr_len;
        le16 gso_size;
        le16 csum_start;
        le16 csum_offset;
        le16 num_buffers;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The controlq is used to control device features such as
filtering.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Legacy Interface: Device Operation<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_net_hdr
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

The legacy driver only presented <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> in the struct virtio_net_hdr
when VIRTIO_NET_F_MRG_RXBUF was not negotiated; without that feature the
structure was <span class="hl num">2</span> bytes shorter.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Packet Transmission<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Packet Transmission<span class="hl opt">}</span>

Transmitting a single packet is simple, but varies depending on
the different features the driver negotiated.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The driver MAY send a completely checksummed packet.  In this case,
  <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> will be zero, and <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span> will be VIRTIO_NET_HDR_GSO_NONE.

<span class="hl kwa">\item</span> If the driver negotiated VIRTIO_NET_F_CSUM, it MAY skip
  checksumming the packet:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item \field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> has the VIRTIO_NET_HDR_F_NEEDS_CSUM set,

  <span class="hl kwa">\item \field</span><span class="hl opt">{</span>csum_start<span class="hl opt">}</span> is set to the offset within the packet to begin checksumming,
    and

  <span class="hl kwa">\item \field</span><span class="hl opt">{</span>csum_offset<span class="hl opt">}</span> indicates how many bytes after the csum_start the
    new (<span class="hl num">16</span> bit ones&apos; complement) checksum is placed by the device.

  <span class="hl kwa">\item</span> The TCP checksum field in the packet is set to the sum
    of the TCP pseudo header, so that replacing it by the ones&apos;
    complement checksum of the TCP header and body will give the
    correct result.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
For example, consider a partially checksummed TCP (IPv4) packet.
It will have a <span class="hl num">14</span> byte ethernet header and <span class="hl num">20</span> byte IP header
followed by the TCP header (with the TCP checksum field <span class="hl num">16</span> bytes
into that header). <span class="hl kwa">\field</span><span class="hl opt">{</span>csum_start<span class="hl opt">}</span> will be <span class="hl num">14</span>+<span class="hl num">20</span> = <span class="hl num">34</span> (the TCP
checksum includes the header), and <span class="hl kwa">\field</span><span class="hl opt">{</span>csum_offset<span class="hl opt">}</span> will be <span class="hl num">16</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\item</span> If the driver negotiated
  VIRTIO_NET_F_HOST_TSO4, TSO6 or UFO, and the packet requires
  TCP segmentation or UDP fragmentation, then <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span>
  is set to VIRTIO_NET_HDR_GSO_TCPV4, TCPV6 or UDP.
  (Otherwise, it is set to VIRTIO_NET_HDR_GSO_NONE). In this
  case, packets larger than <span class="hl num">1514</span> bytes can be transmitted: the
  metadata indicates how to replicate the packet header to cut it
  into smaller packets. The other gso fields are set:

  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item \field</span><span class="hl opt">{</span>hdr_len<span class="hl opt">}</span> is a hint to the device as to how much of the header
    needs to be kept to copy into each packet, usually set to the
    length of the headers, including the transport header<span class="hl kwa">\footnote</span><span class="hl opt">{</span>Due to various bugs in implementations, this field is not useful
as a guarantee of the transport header size.
<span class="hl opt">}</span>.

  <span class="hl kwa">\item \field</span><span class="hl opt">{</span>gso_size<span class="hl opt">}</span> is the maximum size of each packet beyond that
    header (ie. MSS).

  <span class="hl kwa">\item</span> If the driver negotiated the VIRTIO_NET_F_HOST_ECN feature,
    the VIRTIO_NET_HDR_GSO_ECN bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span>
    indicates that the TCP packet has the ECN bit set<span class="hl kwa">\footnote</span><span class="hl opt">{</span>This case is not handled by some older hardware, so is called out
specifically in the protocol.<span class="hl opt">}</span>.
   <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\item \field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> is set to zero.  This field is unused on transmitted packets.

<span class="hl kwa">\item</span> The header and packet are added as one output descriptor to the
  transmitq, and the device is notified of the new entry
  (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Initialization<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Initialization<span class="hl opt">}</span>).
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Packet Transmission<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Packet Transmission<span class="hl opt">}</span>

If a driver has not negotiated VIRTIO_NET_F_CSUM, <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> MUST be zero and
the packet MUST be fully checksummed.

The driver MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> to zero.

A driver SHOULD NOT send TCP packets requiring segmentation offload which have the Explicit Congestion Notification bit set, unless the VIRTIO_NET_F_HOST_ECN feature is
negotiated<span class="hl kwa">\footnote</span><span class="hl opt">{</span>This is a common restriction in real, older network cards.<span class="hl opt">}</span>, in
which case it MUST set the VIRTIO_NET_HDR_GSO_ECN bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span>.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Packet Transmission Interrupt<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Packet Transmission / Packet Transmission Interrupt<span class="hl opt">}</span>

Often a driver will suppress transmission interrupts using the
VIRTQ_AVAIL_F_NO_INTERRUPT flag
 (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device<span class="hl opt">}</span>)
and check for used packets in the transmit path of following
packets.

The normal behavior in this interrupt handler is to retrieve and
new descriptors from the used ring and free the corresponding
headers and packets.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Setting Up Receive Buffers<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span>

It is generally a good idea to keep the receive virtqueue as
fully populated as possible: if it runs out, network performance
will suffer.

If the VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6 or
VIRTIO_NET_F_GUEST_UFO features are used, the maximum incoming packet
will be to <span class="hl num">65550</span> bytes long (the maximum size of a
TCP or UDP packet, plus the <span class="hl num">14</span> byte ethernet header), otherwise
<span class="hl num">1514</span> bytes.  The <span class="hl num">12</span>-byte struct virtio_net_hdr is prepended to this,
making for <span class="hl num">65562</span> or <span class="hl num">1526</span> bytes.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Setting Up Receive Buffers<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> If VIRTIO_NET_F_MRG_RXBUF is not negotiated:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
    <span class="hl kwa">\item</span> If VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6 or
      VIRTIO_NET_F_GUEST_UFO are negotiated, the driver SHOULD populate
      the receive queue(s) with buffers of at least <span class="hl num">65562</span> bytes.
    <span class="hl kwa">\item</span> Otherwise, the driver SHOULD populate the receive queue(s)
      with buffers of at least <span class="hl num">1526</span> bytes.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> If VIRTIO_NET_F_MRG_RXBUF is negotiated, each buffer MUST be at
  greater than the size of the struct virtio_net_hdr.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
Obviously each buffer can be split across multiple descriptor elements.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

If VIRTIO_NET_F_MQ is negotiated, each of receiveq1<span class="hl kwa">\ldots</span> receiveqN
that will be used SHOULD be populated with receive buffers.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Setting Up Receive Buffers<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Setting Up Receive Buffers<span class="hl opt">}</span>

The device MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> to the number of descriptors used to
hold the incoming packet.

The device MUST use only a single descriptor if VIRTIO_NET_F_MRG_RXBUF
was not negotiated. <span class="hl kwa">\note</span><span class="hl opt">{</span>This means that <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> will always be <span class="hl num">1</span> 
if VIRTIO_NET_F_MRG_RXBUF is not negotiated.<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Processing of Packets<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Processing of Packets<span class="hl opt">}</span>

When a packet is copied into a buffer in the receiveq, the
optimal path is to disable further interrupts for the receiveq
(see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device<span class="hl opt">}</span>) and process
packets until no more are found, then re-enable them.

Processing packet involves:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item \field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> indicates how many descriptors
  this packet is spread over (including this one): this will
  always be <span class="hl num">1</span> if VIRTIO_NET_F_MRG_RXBUF was not negotiated.
  This allows receipt of large packets without having to allocate large
  buffers. In this case, there will be at least <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> in
  the used ring, and the device chains them together to form a
  single packet. The other buffers will not begin with a struct
  virtio_net_hdr.

<span class="hl kwa">\item</span> If
  <span class="hl kwa">\field</span><span class="hl opt">{</span>num_buffers<span class="hl opt">}</span> is one, then the entire packet will be
  contained within this buffer, immediately following the struct
  virtio_net_hdr.

<span class="hl kwa">\item</span> If the VIRTIO_NET_F_GUEST_CSUM feature was negotiated, the
  VIRTIO_NET_HDR_F_NEEDS_CSUM bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> MAY be
  set: if so, the checksum on the packet is incomplete and
  <span class="hl kwa">\field</span><span class="hl opt">{</span>csum_start<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>csum_offset<span class="hl opt">}</span> indicate how to calculate
  it (see Packet Transmission point <span class="hl num">1</span>).

<span class="hl kwa">\item</span> If the VIRTIO_NET_F_GUEST_TSO4, TSO6 or UFO options were
  negotiated, then <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span> MAY be something other than
  VIRTIO_NET_HDR_GSO_NONE, and <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_size<span class="hl opt">}</span> field indicates the
  desired MSS (see Packet Transmission point <span class="hl num">2</span>).
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Processing of Packets<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Processing of Packets<span class="hl opt">}</span>

If VIRTIO_NET_F_CSUM is not negotiated, the device MUST set
<span class="hl kwa">\field</span><span class="hl opt">{</span>flags<span class="hl opt">}</span> to zero and the packet MUST be fully checksummed.

If VIRTIO_NET_F_GUEST_TSO4 is not negotiated, the device MUST NOT set
<span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span> to VIRTIO_NET_HDR_GSO_TCPV4.

If VIRTIO_NET_F_GUEST_UDP is not negotiated, the device MUST NOT set
<span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span> to VIRTIO_NET_HDR_GSO_UDP.

If VIRTIO_NET_F_GUEST_TSO6 is not negotiated, the device MUST NOT set
<span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span> to VIRTIO_NET_HDR_GSO_TCPV6.

A device SHOULD NOT send TCP packets requiring segmentation offload
which have the Explicit Congestion Notification bit set, unless the
VIRTIO_NET_F_GUEST_ECN feature is negotiated, in which case it MUST set
the VIRTIO_NET_HDR_GSO_ECN bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>gso_type<span class="hl opt">}</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Control Virtqueue<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue<span class="hl opt">}</span>

The driver uses the control virtqueue (if VIRTIO_NET_F_CTRL_VQ is
negotiated) to send commands to manipulate various features of
the device which would not easily map into the configuration
space.

All commands are of the following form:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_net_ctrl <span class="hl opt">{</span>
        u8 class;
        u8 command;
        u8 command-specific-data<span class="hl opt">[]</span>;
        u8 ack;
<span class="hl opt">}</span>;

/* ack values */
#define VIRTIO_NET_OK     <span class="hl num">0</span>
#define VIRTIO_NET_ERR    <span class="hl num">1</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>class<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>command<span class="hl opt">}</span> and command-specific-data are set by the
driver, and the device sets the <span class="hl kwa">\field</span><span class="hl opt">{</span>ack<span class="hl opt">}</span> byte. There is little it can
do except issue a diagnostic if <span class="hl kwa">\field</span><span class="hl opt">{</span>ack<span class="hl opt">}</span> is not
VIRTIO_NET_OK.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Packet Receive Filtering<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Packet Receive Filtering<span class="hl opt">}</span>

If the VIRTIO_NET_F_CTRL_RX feature is negotiated, the driver can
send control commands for promiscuous mode, multicast receiving,
and filtering of MAC addresses.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
In general, these commands are best-effort: unwanted
packets could still arrive.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Setting Promiscuous Mode<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting Promiscuous Mode<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_NET_CTRL_RX    <span class="hl num">0</span>
 #define VIRTIO_NET_CTRL_RX_PROMISC      <span class="hl num">0</span>
 #define VIRTIO_NET_CTRL_RX_ALLMULTI     <span class="hl num">1</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The class VIRTIO_NET_CTRL_RX has two commands:
VIRTIO_NET_CTRL_RX_PROMISC turns promiscuous mode on and off, and
VIRTIO_NET_CTRL_RX_ALLMULTI turns all-multicast receive on and
off. The command-specific-data is one byte containing <span class="hl num">0</span> (off) or
<span class="hl num">1</span> (on).

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Setting MAC Address Filtering<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_net_ctrl_mac <span class="hl opt">{</span>
        le32 entries;
        u8 macs<span class="hl opt">[</span>entries<span class="hl opt">][</span><span class="hl num">6</span><span class="hl opt">]</span>;
<span class="hl opt">}</span>;

#define VIRTIO_NET_CTRL_MAC    <span class="hl num">1</span>
 #define VIRTIO_NET_CTRL_MAC_TABLE_SET        <span class="hl num">0</span>
 #define VIRTIO_NET_CTRL_MAC_ADDR_SET         <span class="hl num">1</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The device can filter incoming packets by any number of destination
MAC addresses<span class="hl kwa">\footnote</span><span class="hl opt">{</span>Since there are no guarantees, it can use a hash filter or
silently switch to allmulti or promiscuous mode if it is given too
many addresses.
<span class="hl opt">}</span>. This table is set using the class
VIRTIO_NET_CTRL_MAC and the command VIRTIO_NET_CTRL_MAC_TABLE_SET. The
command-specific-data is two variable length tables of <span class="hl num">6</span>-byte MAC
addresses (as described in struct virtio_net_ctrl_mac). The first table contains unicast addresses, and the second
contains multicast addresses.

The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the
default MAC address which rx filtering
accepts (and if VIRTIO_NET_F_MAC_ADDR has been negotiated,
this will be reflected in <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> in config space).

The command-specific-data for VIRTIO_NET_CTRL_MAC_ADDR_SET is
the <span class="hl num">6</span>-byte MAC address.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Setting MAC Address Filtering<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering<span class="hl opt">}</span>

The device MUST have an empty MAC filtering table on reset.

The device MUST update the MAC filtering table before it consumes
the VIRTIO_NET_CTRL_MAC_TABLE_SET command.

The device MUST update <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> in config space before it consumes
the VIRTIO_NET_CTRL_MAC_ADDR_SET command, if VIRTIO_NET_F_MAC_ADDR has
been negotiated.

The device SHOULD drop incoming packets which have a destination MAC which
matches neither the <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> (or that set with VIRTIO_NET_CTRL_MAC_ADDR_SET)
nor the MAC filtering table.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Setting MAC Address Filtering<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering<span class="hl opt">}</span>

The driver MUST follow the VIRTIO_NET_CTRL_MAC_TABLE_SET command
by a le32 number, followed by that number of non-multicast
MAC addresses, followed by another le32 number, followed by
that number of multicast addresses.  Either number MAY be <span class="hl num">0</span>.

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: Setting MAC Address Filtering<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering / Legacy Interface: Setting MAC Address Filtering<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format <span class="hl kwa">\field</span><span class="hl opt">{</span>entries<span class="hl opt">}</span> in struct virtio_net_ctrl_mac
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

Legacy drivers that didn&apos;t negotiate VIRTIO_NET_F_CTRL_MAC_ADDR
changed <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> in config space when NIC is accepting
incoming packets. These drivers always wrote the mac value from
first to last byte, therefore after detecting such drivers,
a transitional device MAY defer MAC update, or MAY defer
processing incoming packets until driver writes the last byte
of <span class="hl kwa">\field</span><span class="hl opt">{</span>mac<span class="hl opt">}</span> in the config space.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>VLAN Filtering<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering<span class="hl opt">}</span>

If the driver negotiates the VIRTION_NET_F_CTRL_VLAN feature, it
can control a VLAN filter table in the device.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_NET_CTRL_VLAN       <span class="hl num">2</span>
 #define VIRTIO_NET_CTRL_VLAN_ADD             <span class="hl num">0</span>
 #define VIRTIO_NET_CTRL_VLAN_DEL             <span class="hl num">1</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

Both the VIRTIO_NET_CTRL_VLAN_ADD and VIRTIO_NET_CTRL_VLAN_DEL
command take a little-endian <span class="hl num">16</span>-bit VLAN id as the command-specific-data.

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: VLAN Filtering<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering / Legacy Interface: VLAN Filtering<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the VLAN id
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Gratuitous Packet Sending<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending<span class="hl opt">}</span>

If the driver negotiates the VIRTIO_NET_F_GUEST_ANNOUNCE (depends
on VIRTIO_NET_F_CTRL_VQ), the device can ask the driver to send gratuitous
packets; this is usually done after the guest has been physically
migrated, and needs to announce its presence on the new network
links. (As hypervisor does not have the knowledge of guest
network configuration (eg. tagged vlan) it is simplest to prod
the guest in this way).

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_NET_CTRL_ANNOUNCE       <span class="hl num">3</span>
 #define VIRTIO_NET_CTRL_ANNOUNCE_ACK             <span class="hl num">0</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The driver checks VIRTIO_NET_S_ANNOUNCE bit in the device configuration <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> field
when it notices the changes of device configuration. The
command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
driver has received the notification and device clears the
VIRTIO_NET_S_ANNOUNCE bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>.

Processing this notification involves:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Sending the gratuitous packets (eg. ARP) or marking there are pending
  gratuitous packets to be sent and letting deferred routine to
  send them.

<span class="hl kwa">\item</span> Sending VIRTIO_NET_CTRL_ANNOUNCE_ACK command through control
  vq.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Gratuitous Packet Sending<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending<span class="hl opt">}</span>

If the driver negotiates VIRTIO_NET_F_GUEST_ANNOUNCE, it SHOULD notify
network peers of its new location after it sees the VIRTIO_NET_S_ANNOUNCE bit
in <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>.  The driver MUST send a command on the command queue
with class VIRTIO_NET_CTRL_ANNOUNCE and command VIRTIO_NET_CTRL_ANNOUNCE_ACK.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Gratuitous Packet Sending<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending<span class="hl opt">}</span>

If VIRTIO_NET_F_GUEST_ANNOUNCE is negotiated, the device MUST clear the
VIRTIO_NET_S_ANNOUNCE bit in <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> upon receipt of a command buffer
with class VIRTIO_NET_CTRL_ANNOUNCE and command VIRTIO_NET_CTRL_ANNOUNCE_ACK
before marking the buffer as used.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Automatic receive steering in multiqueue mode<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode<span class="hl opt">}</span>

If the driver negotiates the VIRTIO_NET_F_MQ feature bit (depends
on VIRTIO_NET_F_CTRL_VQ), it MAY transmit outgoing packets on one
of the multiple transmitq1<span class="hl kwa">\ldots</span> transmitqN and ask the device to
queue incoming packets into one of the multiple receiveq1<span class="hl kwa">\ldots</span> receiveqN
depending on the packet flow.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_net_ctrl_mq <span class="hl opt">{</span>
        le16 virtqueue_pairs;
<span class="hl opt">}</span>;

#define VIRTIO_NET_CTRL_MQ    <span class="hl num">4</span>
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET        <span class="hl num">0</span>
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        <span class="hl num">1</span>
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        <span class="hl num">0x8000</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

Multiqueue is disabled by default. The driver enables multiqueue by
executing the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command, specifying
the number of the transmit and receive queues to be used up to
<span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span>; subsequently,
transmitq1<span class="hl kwa">\ldots</span> transmitqn and receiveq1<span class="hl kwa">\ldots</span> receiveqn where
n=<span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span> MAY be used.

When multiqueue is enabled, the device MUST use automatic receive steering
based on packet flow. Programming of the receive steering
classificator is implicit. After the driver transmitted a packet of a
flow on transmitqX, the device SHOULD cause incoming packets for that flow to
be steered to receiveqX. For uni-directional protocols, or where
no packets have been transmitted yet, the device MAY steer a packet
to a random queue out of the specified receiveq1<span class="hl kwa">\ldots</span> receiveqn.

Multiqueue is disabled by setting <span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span> to <span class="hl num">1</span> (this is
the default) and waiting for the device to use the command buffer.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Automatic receive steering in multiqueue mode<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode<span class="hl opt">}</span>

The driver MUST configure the virtqueues before enabling them with the 
VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command.

The driver MUST NOT request a <span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span> of <span class="hl num">0</span> or
greater than <span class="hl kwa">\field</span><span class="hl opt">{</span>max_virtqueue_pairs<span class="hl opt">}</span> in the device configuration space.

The driver MUST queue packets only on any transmitq1 before the 
VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command.

The driver MUST NOT queue packets on transmit queues greater than
<span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span> once it has placed the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command in the available ring.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Automatic receive steering in multiqueue mode<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode<span class="hl opt">}</span>

The device MUST queue packets only on any receiveq1 before the 
VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command.

The device MUST NOT queue packets on receive queues greater than
<span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span> once it has placed the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command in the used ring.

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: Automatic receive steering in multiqueue mode<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Legacy Interface: Automatic receive steering in multiqueue mode<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format <span class="hl kwa">\field</span><span class="hl opt">{</span>virtqueue_pairs<span class="hl opt">}</span>
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Offloads State Configuration<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration<span class="hl opt">}</span>

If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can
send control commands for dynamic offloads state configuration.

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Setting Offloads State<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
le64 offloads;

#define VIRTIO_NET_F_GUEST_CSUM       <span class="hl num">1</span>
#define VIRTIO_NET_F_GUEST_TSO4       <span class="hl num">7</span>
#define VIRTIO_NET_F_GUEST_TSO6       <span class="hl num">8</span>
#define VIRTIO_NET_F_GUEST_ECN        <span class="hl num">9</span>
#define VIRTIO_NET_F_GUEST_UFO        <span class="hl num">10</span>

#define VIRTIO_NET_CTRL_GUEST_OFFLOADS       <span class="hl num">5</span>
 #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET   <span class="hl num">0</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The class VIRTIO_NET_CTRL_GUEST_OFFLOADS has one command:
VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET applies the new offloads configuration.

le64 value passed as command data is a bitmask, bits set define
offloads to be enabled, bits cleared - offloads to be disabled.

There is a corresponding device feature for each offload. Upon feature
negotiation corresponding offload gets enabled to preserve backward
compartibility.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subparagraph</span><span class="hl opt">}{</span>Setting Offloads State<span class="hl opt">}{</span>Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State<span class="hl opt">}</span>

A driver MUST NOT enable an offload for which the appropriate feature
has not been negotiated.

<span class="hl kwa">\subparagraph</span><span class="hl opt">{</span>Legacy Interface: Setting Offloads State<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State / Legacy Interface: Setting Offloads State<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format <span class="hl kwa">\field</span><span class="hl opt">{</span>offloads<span class="hl opt">}</span>
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.


<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Framing Requirements<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device
Types / Network Device / Legacy Interface: Framing Requirements<span class="hl opt">}</span>

When using legacy interfaces, transitional drivers which have not
negotiated VIRTIO_F_ANY_LAYOUT MUST use a single descriptor for the
struct virtio_net_hdr on both transmit and receive, with the
network data in the following descriptors.

Additionally, when using the control virtqueue (see <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Device
Types / Network Device / Device Operation / Control Virtqueue<span class="hl opt">}</span>)
, transitional drivers which have not
negotiated VIRTIO_F_ANY_LAYOUT MUST:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> for all commands, use a single <span class="hl num">2</span>-byte descriptor including the first two
fields: <span class="hl kwa">\field</span><span class="hl opt">{</span>class<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>command<span class="hl opt">}</span>
<span class="hl kwa">\item</span> for all commands except VIRTIO_NET_CTRL_MAC_TABLE_SET
use a single descriptor including command-specific-data
with no padding.
<span class="hl kwa">\item</span> for the VIRTIO_NET_CTRL_MAC_TABLE_SET command use exactly
two descriptors including command-specific-data with no padding:
the first of these descriptors MUST include the
virtio_net_ctrl_mac table structure for the unicast addresses with no padding,
the second of these descriptors MUST include the
virtio_net_ctrl_mac table structure for the multicast addresses
with no padding.
<span class="hl kwa">\item</span> for all commands, use a single <span class="hl num">1</span>-byte descriptor for the
<span class="hl kwa">\field</span><span class="hl opt">{</span>ack<span class="hl opt">}</span> field
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic
Facilities of a Virtio Device / Virtqueues / Message Framing<span class="hl opt">}</span>.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Block Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device<span class="hl opt">}</span>

The virtio block device is a simple virtual block device (ie.
disk). Read and write requests (and other exotic requests) are
placed in the queue, and serviced (probably out of order) by the
device except where noted.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device ID<span class="hl opt">}</span>
  <span class="hl num">2</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Virtqueues<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> requestq
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Feature bits<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_SIZE_MAX (<span class="hl num">1</span>)<span class="hl opt">]</span> Maximum size of any single segment is
    in <span class="hl kwa">\field</span><span class="hl opt">{</span>size_max<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_SEG_MAX (<span class="hl num">2</span>)<span class="hl opt">]</span> Maximum number of segments in a
    request is in <span class="hl kwa">\field</span><span class="hl opt">{</span>seg_max<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_GEOMETRY (<span class="hl num">4</span>)<span class="hl opt">]</span> Disk-style geometry specified in
    <span class="hl kwa">\field</span><span class="hl opt">{</span>geometry<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_RO (<span class="hl num">5</span>)<span class="hl opt">]</span> Device is read-only.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_BLK_SIZE (<span class="hl num">6</span>)<span class="hl opt">]</span> Block size of disk is in <span class="hl kwa">\field</span><span class="hl opt">{</span>blk_size<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_TOPOLOGY (<span class="hl num">10</span>)<span class="hl opt">]</span> Device exports information on optimal I/O
    alignment.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Feature bits / Legacy Interface: Feature bits<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_BARRIER (<span class="hl num">0</span>)<span class="hl opt">]</span> Device supports request barriers.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_SCSI (<span class="hl num">7</span>)<span class="hl opt">]</span> Device supports scsi packet commands.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_FLUSH (<span class="hl num">9</span>)<span class="hl opt">]</span> Cache flush command support.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BLK_F_CONFIG_WCE (<span class="hl num">11</span>)<span class="hl opt">]</span> Device can toggle its cache between writeback
    and writethrough modes.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

VIRTIO_BLK_F_FLUSH was also called VIRTIO_BLK_F_WCE: Legacy drivers
MUST only negotiate this feature if they are capable of sending
VIRTIO_BLK_T_FLUSH commands.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device configuration layout<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>capacity<span class="hl opt">}</span> of the device (expressed in <span class="hl num">512</span>-byte sectors) is always
present. The availability of the others all depend on various feature
bits as indicated above.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_blk_config <span class="hl opt">{</span>
        le64 capacity;
        le32 size_max;
        le32 seg_max;
        struct virtio_blk_geometry <span class="hl opt">{</span>
                le16 cylinders;
                u8 heads;
                u8 sectors;
        <span class="hl opt">}</span> geometry;
        le32 blk_size;
        struct virtio_blk_topology <span class="hl opt">{</span>
                // # of logical blocks per physical block (log2)
                u8 physical_block_exp;
                // offset of first aligned logical block
                u8 alignment_offset;
                // suggested minimum I/O size in blocks
                le16 min_io_size;
                // optimal (suggested maximum) I/O size in blocks
                le32 opt_io_size;
        <span class="hl opt">}</span> topology;
        u8 reserved;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>


<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device configuration layout / Legacy Interface: Device configuration layout<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_blk_config
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.


<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device size can be read from <span class="hl kwa">\field</span><span class="hl opt">{</span>capacity<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> If the VIRTIO_BLK_F_BLK_SIZE feature is negotiated,
  <span class="hl kwa">\field</span><span class="hl opt">{</span>blk_size<span class="hl opt">}</span> can be read to determine the optimal sector size
  for the driver to use. This does not affect the units used in
  the protocol (always <span class="hl num">512</span> bytes), but awareness of the correct
  value can affect performance.

<span class="hl kwa">\item</span> If the VIRTIO_BLK_F_RO feature is set by the device, any write
  requests will fail.

<span class="hl kwa">\item</span> If the VIRTIO_BLK_F_TOPOLOGY feature is negotiated, the fields in the
  <span class="hl kwa">\field</span><span class="hl opt">{</span>topology<span class="hl opt">}</span> struct can be read to determine the physical block size and optimal
  I/O lengths for the driver to use. This also does not affect the units
  in the protocol, only performance.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Initialization / Legacy Interface: Device Initialization<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>reserved<span class="hl opt">}</span> field used to be called <span class="hl kwa">\field</span><span class="hl opt">{</span>writeback<span class="hl opt">}</span>.  If the
VIRTIO_BLK_F_CONFIG_WCE feature is offered, the cache mode can be
read from <span class="hl kwa">\field</span><span class="hl opt">{</span>writeback<span class="hl opt">}</span>; the
driver can also write to the field in order to toggle the cache
between writethrough (<span class="hl num">0</span>) and writeback (<span class="hl num">1</span>) mode.  If the feature is
not available, the driver can instead look at the result of
negotiating VIRTIO_BLK_F_FLUSH: the cache will be in writeback mode
after reset if and only if VIRTIO_BLK_F_FLUSH is negotiated.

Some older legacy devices did not operate in writethrough mode even
after a driver announced lack of support for VIRTIO_BLK_F_FLUSH.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Operation<span class="hl opt">}</span>

The driver queues requests to the virtqueue, and they are used by
the device (not necessarily in order). Each request is of form:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_blk_req <span class="hl opt">{</span>
        le32 type;
        le32 reserved;
        le64 sector;
        u8 data<span class="hl opt">[][</span><span class="hl num">512</span><span class="hl opt">]</span>;
        u8 status;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The type of the request is either a read (VIRTIO_BLK_T_IN), a write
(VIRTIO_BLK_T_OUT), or a flush (VIRTIO_BLK_T_FLUSH).

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_BLK_T_IN           <span class="hl num">0</span>
#define VIRTIO_BLK_T_OUT          <span class="hl num">1</span>
#define VIRTIO_BLK_T_FLUSH        <span class="hl num">4</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>sector<span class="hl opt">}</span> number indicates the offset (multiplied by <span class="hl num">512</span>) where
the read or write is to occur. This field is unused and set to <span class="hl num">0</span>
for scsi packet commands and for flush commands.

The final <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> byte is written by the device: either
VIRTIO_BLK_S_OK for success, VIRTIO_BLK_S_IOERR for device or driver
error or VIRTIO_BLK_S_UNSUPP for a request unsupported by device:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_BLK_S_OK        <span class="hl num">0</span>
#define VIRTIO_BLK_S_IOERR     <span class="hl num">1</span>
#define VIRTIO_BLK_S_UNSUPP    <span class="hl num">2</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Block Device / Device Operation<span class="hl opt">}</span>

A driver MUST NOT submit a request which would cause a read or write
beyond <span class="hl kwa">\field</span><span class="hl opt">{</span>capacity<span class="hl opt">}</span>.

A driver SHOULD accept the VIRTIO_BLK_F_RO feature if offered.

A driver MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>sector<span class="hl opt">}</span> to <span class="hl num">0</span> for a VIRTIO_BLK_T_FLUSH request.
A driver SHOULD NOT include any data in a VIRTIO_BLK_T_FLUSH request.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Block Device / Device Operation<span class="hl opt">}</span>

A device MUST set the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> byte to VIRTIO_BLK_S_IOERR
for a write request if the VIRTIO_BLK_F_RO feature if offered, and MUST NOT
write any data.

Upon receipt of a VIRTIO_BLK_T_FLUSH request, the driver SHOULD ensure
that any writes which were completed are committed to non-volatile storage.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Block Device / Device Operation / Legacy Interface: Device Operation<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_blk_req
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

The <span class="hl kwa">\field</span><span class="hl opt">{</span>reserved<span class="hl opt">}</span> field was previously called <span class="hl kwa">\field</span><span class="hl opt">{</span>ioprio<span class="hl opt">}</span>.  <span class="hl kwa">\field</span><span class="hl opt">{</span>ioprio<span class="hl opt">}</span>
is a hint about the relative priorities of requests to the device:
higher numbers indicate more important requests.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_BLK_T_FLUSH_OUT    <span class="hl num">5</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The command VIRTIO_BLK_T_FLUSH_OUT was a synonym for VIRTIO_BLK_T_FLUSH;
a driver MUST treat it as a VIRTIO_BLK_T_FLUSH command.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_BLK_T_BARRIER     <span class="hl num">0x80000000</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

If the device has VIRTIO_BLK_F_BARRIER
feature the high bit (VIRTIO_BLK_T_BARRIER) indicates that this
request acts as a barrier and that all preceding requests SHOULD be
complete before this one, and all following requests SHOULD NOT be
started until this is complete.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span> A barrier does not flush
caches in the underlying backend device in host, and thus does not
serve as data consistency guarantee.  Only a VIRTIO_BLK_T_FLUSH request
does that.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

If the device has VIRTIO_BLK_F_SCSI feature, it can also support
scsi packet command requests, each of these requests is of form:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
/* All fields are in guest&apos;s native endian. */
struct virtio_scsi_pc_req <span class="hl opt">{</span>
        u32 type;
        u32 ioprio;
        u64 sector;
        u8 cmd<span class="hl opt">[]</span>;
        u8 data<span class="hl opt">[][</span><span class="hl num">512</span><span class="hl opt">]</span>;
#define SCSI_SENSE_BUFFERSIZE   <span class="hl num">96</span>
        u8 sense<span class="hl opt">[</span>SCSI_SENSE_BUFFERSIZE<span class="hl opt">]</span>;
        u32 errors;
        u32 data_len;
        u32 sense_len;
        u32 residual;
        u8 status;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

A request type can also be a scsi packet command (VIRTIO_BLK_T_SCSI_CMD or
VIRTIO_BLK_T_SCSI_CMD_OUT).  The two types are equivalent, the device
does not distinguish between them:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_BLK_T_SCSI_CMD     <span class="hl num">2</span>
#define VIRTIO_BLK_T_SCSI_CMD_OUT <span class="hl num">3</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>cmd<span class="hl opt">}</span> field is only present for scsi packet command requests,
and indicates the command to perform. This field MUST reside in a
single, separate device-readable buffer; command length can be derived
from the length of this buffer.

Note that these first three (four for scsi packet commands)
fields are always device-readable: <span class="hl kwa">\field</span><span class="hl opt">{</span>data<span class="hl opt">}</span> is either device-readable
or device-writable, depending on the request. The size of the read or
write can be derived from the total size of the request buffers.

<span class="hl kwa">\field</span><span class="hl opt">{</span>sense<span class="hl opt">}</span> is only present for scsi packet command requests,
and indicates the buffer for scsi sense data.

<span class="hl kwa">\field</span><span class="hl opt">{</span>data_len<span class="hl opt">}</span> is only present for scsi packet command
requests, this field is deprecated, and SHOULD be ignored by the
driver. Historically, devices copied data length there.

<span class="hl kwa">\field</span><span class="hl opt">{</span>sense_len<span class="hl opt">}</span> is only present for scsi packet command
requests and indicates the number of bytes actually written to
the <span class="hl kwa">\field</span><span class="hl opt">{</span>sense<span class="hl opt">}</span> buffer.

<span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> field is only present for scsi packet command
requests and indicates the residual size, calculated as data
length - number of bytes actually transferred.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Framing Requirements<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device
Types / Block Device / Legacy Interface: Framing Requirements<span class="hl opt">}</span>

When using legacy interfaces, transitional drivers which have not
negotiated VIRTIO_F_ANY_LAYOUT:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> MUST use a single <span class="hl num">8</span>-byte descriptor containing <span class="hl kwa">\field</span><span class="hl opt">{</span>type<span class="hl opt">}</span>,
  <span class="hl kwa">\field</span><span class="hl opt">{</span>reseved<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>sector<span class="hl opt">}</span>, followed by descriptors
  for <span class="hl kwa">\field</span><span class="hl opt">{</span>data<span class="hl opt">}</span>, then finally a separate <span class="hl num">1</span>-byte descriptor
  for <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> For SCSI commands there are additional constraints.
  <span class="hl kwa">\field</span><span class="hl opt">{</span>errors<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>data_len<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>sense_len<span class="hl opt">}</span> and
  <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> MUST reside in a single, separate
  device-writable descriptor, <span class="hl kwa">\field</span><span class="hl opt">{</span>sense<span class="hl opt">}</span> MUST reside in a
  single separate device-writable descriptor of size <span class="hl num">96</span> bytes,
  and <span class="hl kwa">\field</span><span class="hl opt">{</span>errors<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>data_len<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>sense_len<span class="hl opt">}</span> and
  <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> MUST reside a single separate
  device-writable descriptor.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

See <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing<span class="hl opt">}</span>.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Console Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device<span class="hl opt">}</span>

The virtio console device is a simple device for data input and
output. A device MAY have one or more ports. Each port has a pair
of input and output virtqueues. Moreover, a device has a pair of
control IO virtqueues. The control virtqueues are used to
communicate information between the device and the driver about
ports being opened and closed on either side of the connection,
indication from the device about whether a particular port is a
console port, adding new ports, port hot-plug/unplug, etc., and
indication from the driver about whether a port or a device was
successfully added, port open/close, etc. For data IO, one or
more empty buffers are placed in the receive queue for incoming
data and outgoing characters are placed in the transmit queue.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device ID<span class="hl opt">}</span>

  <span class="hl num">3</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Virtqueues<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> receiveq(port0)
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">1</span><span class="hl opt">]</span> transmitq(port0)
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span><span class="hl opt">]</span> control receiveq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">3</span><span class="hl opt">]</span> control transmitq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">4</span><span class="hl opt">]</span> receiveq(port1)
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">5</span><span class="hl opt">]</span> transmitq(port1)
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\ldots</span><span class="hl opt">]</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

The port <span class="hl num">0</span> receive and transmit queues always exist: other queues
only exist if VIRTIO_CONSOLE_F_MULTIPORT is set.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Feature bits<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_CONSOLE_F_SIZE (<span class="hl num">0</span>)<span class="hl opt">]</span> Configuration <span class="hl kwa">\field</span><span class="hl opt">{</span>cols<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>rows<span class="hl opt">}</span>
    are valid.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_CONSOLE_F_MULTIPORT (<span class="hl num">1</span>)<span class="hl opt">]</span> Device has support for multiple
    ports; <span class="hl kwa">\field</span><span class="hl opt">{</span>max_nr_ports<span class="hl opt">}</span> is valid and control virtqueues will be used.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_CONSOLE_F_EMERG_WRITE (<span class="hl num">2</span>)<span class="hl opt">]</span> Device has support for emergency write.
    Configuration field emerg_wr is valid.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device configuration layout<span class="hl opt">}</span>

  The size of the console is supplied
  in the configuration space if the VIRTIO_CONSOLE_F_SIZE feature
  is set. Furthermore, if the VIRTIO_CONSOLE_F_MULTIPORT feature
  is set, the maximum number of ports supported by the device can
  be fetched.

  If VIRTIO_CONSOLE_F_EMERG_WRITE is set then the driver can use emergency write
  to output a single character without initializing virtio queues, or even
  acknowledging the feature.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_console_config <span class="hl opt">{</span>
        le16 cols;
        le16 rows;
        le32 max_nr_ports;
        le32 emerg_wr;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device configuration layout / Legacy Interface: Device configuration layout<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_console_config
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> If the VIRTIO_CONSOLE_F_EMERG_WRITE feature is offered,
  <span class="hl kwa">\field</span><span class="hl opt">{</span>emerg_wr<span class="hl opt">}</span> field of the configuration can be written at any time.
  Thus it works for very early boot debugging output as well as
  catastophic OS failures (eg. virtio ring corruption).

<span class="hl kwa">\item</span> If the VIRTIO_CONSOLE_F_SIZE feature is negotiated, the driver
  can read the console dimensions from <span class="hl kwa">\field</span><span class="hl opt">{</span>cols<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>rows<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> If the VIRTIO_CONSOLE_F_MULTIPORT feature is negotiated, the
  driver can spawn multiple ports, not all of which are necessarily
  attached to a console. Some could be generic ports. In this
  case, the control virtqueues are enabled and according to
  <span class="hl kwa">\field</span><span class="hl opt">{</span>max_nr_ports<span class="hl opt">}</span>, the appropriate number
  of virtqueues are created. A control message indicating the
  driver is ready is sent to the device. The device can then send
  control messages for adding new ports to the device. After
  creating and initializing each port, a
  VIRTIO_CONSOLE_PORT_READY control message is sent to the device
  for that port so the device can let the driver know of any additional
  configuration options set for that port.

<span class="hl kwa">\item</span> The receiveq for each port is populated with one or more
  receive buffers.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Initialization<span class="hl opt">}{</span>Device Types / Console Device / Device Initialization<span class="hl opt">}</span>

The device MUST allow a write to <span class="hl kwa">\field</span><span class="hl opt">{</span>emerg_wr<span class="hl opt">}</span>, even on an
unconfigured device.

The device SHOULD transmit the lower byte written to <span class="hl kwa">\field</span><span class="hl opt">{</span>emerg_wr<span class="hl opt">}</span> to
an appropriate log or output method.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device Operation<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> For output, a buffer containing the characters is placed in
  the port&apos;s transmitq<span class="hl kwa">\footnote</span><span class="hl opt">{</span>Because this is high importance and low bandwidth, the current
Linux implementation polls for the buffer to be used, rather than
waiting for an interrupt, simplifying the implementation
significantly. However, for generic serial ports with the
O_NONBLOCK flag set, the polling limitation is relaxed and the
consumed buffers are freed upon the next write or poll call or
when a port is closed or hot-unplugged.
<span class="hl opt">}</span>.

<span class="hl kwa">\item</span> When a buffer is used in the receiveq (signalled by an
  interrupt), the contents is the input to the port associated
  with the virtqueue for which the notification was received.

<span class="hl kwa">\item</span> If the driver negotiated the VIRTIO_CONSOLE_F_SIZE feature, a
  configuration change interrupt indicates that the updated size can
  be read from the configuration fields.  This size applies to port <span class="hl num">0</span> only.

<span class="hl kwa">\item</span> If the driver negotiated the VIRTIO_CONSOLE_F_MULTIPORT
  feature, active ports are announced by the device using the
  VIRTIO_CONSOLE_PORT_ADD control message. The same message is
  used for port hot-plug as well.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Console Device / Device Operation<span class="hl opt">}</span>

The driver MUST NOT put a device-readable in a receiveq. The driver
MUST NOT put a device-writable buffer in a transmitq.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Multiport Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device Operation / Multiport Device Operation<span class="hl opt">}</span>

If the driver negotiated the VIRTIO_CONSOLE_F_MULTIPORT, the two
control queues are used to manipulate the different console ports: the
control receiveq for messages from the device to the driver, and the
control sendq for driver-to-device messages.  The layout of the
control messages is:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_console_control <span class="hl opt">{</span>
        le32 id;    /* Port number */
        le16 event; /* The kind of control event */
        le16 value; /* Extra information for the event */
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The values for <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> are:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_DEVICE_READY (<span class="hl num">0</span>)<span class="hl opt">]</span> Sent by the driver at initialization
  to indicate that it is ready to receive control messages.  A value of
  <span class="hl num">1</span> indicates success, and <span class="hl num">0</span> indicates failure.  The port number <span class="hl kwa">\field</span><span class="hl opt">{</span>id<span class="hl opt">}</span> is unused.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_DEVICE_ADD (<span class="hl num">1</span>)<span class="hl opt">]</span> Sent by the device, to create a new
  port.  <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> is unused.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_DEVICE_REMOVE (<span class="hl num">2</span>)<span class="hl opt">]</span> Sent by the device, to remove an
  existing port. <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> is unused.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_PORT_READY (<span class="hl num">3</span>)<span class="hl opt">]</span> Sent by the driver in response
  to the device&apos;s VIRTIO_CONSOLE_PORT_ADD message, to indicate that
  the port is ready to be used. A <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> of <span class="hl num">1</span> indicates success, and <span class="hl num">0</span>
  indicates failure.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_CONSOLE_PORT (<span class="hl num">4</span>)<span class="hl opt">]</span> Sent by the device to nominate
  a port as a console port.  There MAY be more than one console port.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_RESIZE (<span class="hl num">5</span>)<span class="hl opt">]</span> Sent by the device to indicate
  a console size change.  <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> is unused.  The buffer is followed by the number of columns and rows:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_console_resize <span class="hl opt">{</span>
        le16 cols;
        le16 rows;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_PORT_OPEN (<span class="hl num">6</span>)<span class="hl opt">]</span> This message is sent by both the
  device and the driver.  <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> indicates the state: <span class="hl num">0</span> (port
  closed) or <span class="hl num">1</span> (port open).  This allows for ports to be used directly
  by guest and host processes to communicate in an application-defined
  manner.
<span class="hl kwa">\item</span> <span class="hl opt">[</span>VIRTIO_CONSOLE_PORT_NAME (<span class="hl num">7</span>)<span class="hl opt">]</span> Sent by the device to give a tag
  to the port.  This control command is immediately
  followed by the UTF-<span class="hl num">8</span> name of the port for identification
  within the guest (without a NUL terminator).
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Multiport Device Operation<span class="hl opt">}{</span>Device Types / Console Device / Device Operation / Multiport Device Operation<span class="hl opt">}</span>

The device MUST NOT specify a port which exists in a
VIRTIO_CONSOLE_DEVICE_ADD message, nor a port which is equal or
greater than <span class="hl kwa">\field</span><span class="hl opt">{</span>max_nr_ports<span class="hl opt">}</span>.

The device MUST NOT specify a port in VIRTIO_CONSOLE_DEVICE_REMOVE
which has not been created with a previous VIRTIO_CONSOLE_DEVICE_ADD.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Multiport Device Operation<span class="hl opt">}{</span>Device Types / Console Device / Device Operation / Multiport Device Operation<span class="hl opt">}</span>

The driver MUST send a VIRTIO_CONSOLE_DEVICE_READY message if
VIRTIO_CONSOLE_F_MULTIPORT is negotiated.

Upon receipt of a VIRTIO_CONSOLE_CONSOLE_PORT message, the driver
SHOULD treat the port in a manner suitable for text console access
and MUST respond with a VIRTIO_CONSOLE_PORT_OPEN message, which MUST
have <span class="hl kwa">\field</span><span class="hl opt">{</span>value<span class="hl opt">}</span> set to <span class="hl num">1</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Console Device / Device Operation / Legacy Interface: Device Operation<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_console_control
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Framing Requirements<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device
Types / Console Device / Legacy Interface: Framing Requirements<span class="hl opt">}</span>

When using legacy interfaces, transitional drivers which have not
negotiated VIRTIO_F_ANY_LAYOUT MUST use only a single
descriptor for all buffers in the control receiveq and control transmitq.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Entropy Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device<span class="hl opt">}</span>

The virtio entropy device supplies high-quality randomness for
guest use.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Device ID<span class="hl opt">}</span>
  <span class="hl num">4</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Virtqueues<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> requestq
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Feature bits<span class="hl opt">}</span>
  None currently defined

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Device configuration layout<span class="hl opt">}</span>
  None currently defined.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The virtqueue is initialized
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Entropy Device / Device Operation<span class="hl opt">}</span>

When the driver requires random bytes, it places the descriptor
of one or more buffers in the queue. It will be completely filled
by random data by the device.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Entropy Device / Device Operation<span class="hl opt">}</span>

The driver MUST NOT place driver-readable buffers into the queue.

The driver MUST examine the length written by the driver to determine
how many random bytes were received.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Entropy Device / Device Operation<span class="hl opt">}</span>

The device MUST place one or more random bytes into the buffer, but it
MAY use less than the entire buffer length.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Legacy Interface: Memory Balloon Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device<span class="hl opt">}</span>

This device is deprecated, and thus only exists as a legacy device
illustrated here for reference.  The device number <span class="hl num">13</span> is reserved for
a new memory balloon interface which is expected in a future version
of the standard.

The virtio memory balloon device is a primitive device for
managing guest memory: the device asks for a certain amount of
memory, and the driver supplies it (or withdraws it, if the device
has more than it asks for). This allows the guest to adapt to
changes in allowance of underlying physical memory. If the
feature is negotiated, the device can also be used to communicate
guest memory statistics to the host.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device ID<span class="hl opt">}</span>
  <span class="hl num">5</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Virtqueues<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> inflateq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">1</span><span class="hl opt">]</span> deflateq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span><span class="hl opt">]</span> statsq.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

  Virtqueue <span class="hl num">2</span> only exists if VIRTIO_BALLON_F_STATS_VQ set.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Feature bits<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_F_MUST_TELL_HOST (<span class="hl num">0</span>)<span class="hl opt">]</span> Host MUST be told before
    pages from the balloon are used.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_F_STATS_VQ (<span class="hl num">1</span>)<span class="hl opt">]</span> A virtqueue for reporting guest
    memory statistics is present.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device configuration layout<span class="hl opt">}</span>
  Both fields of this configuration
  are always available.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_balloon_config <span class="hl opt">{</span>
        le32 num_pages;
        le32 actual;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

Note that these fields are always little endian, despite convention
that legacy device fields are guest endian.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Initialization<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device Initialization<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The inflate and deflate virtqueues are identified.

<span class="hl kwa">\item</span> If the VIRTIO_BALLOON_F_STATS_VQ feature bit is negotiated:
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> Identify the stats virtqueue.

  <span class="hl kwa">\item</span> Add one empty buffer to the stats virtqueue and notify the
    device.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

Device operation begins immediately.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device Operation<span class="hl opt">}</span>

The device is driven by the receipt of a
configuration change interrupt.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item \field</span><span class="hl opt">{</span>num_pages<span class="hl opt">}</span> configuration field is examined. If this is
  greater than the <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span> number of pages, the balloon wants
  more memory from the guest.  If it is less than <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span>,
  the balloon doesn&apos;t need it all.

<span class="hl kwa">\item</span> To supply memory to the balloon (aka. inflate):
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> The driver constructs an array of addresses of unused memory
    pages. These addresses are divided by <span class="hl num">4096</span><span class="hl kwa">\footnote</span><span class="hl opt">{</span>This is historical, and independent of the guest page size.
<span class="hl opt">}</span> and the descriptor
    describing the resulting <span class="hl num">32</span>-bit array is added to the inflateq.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\item</span> To remove memory from the balloon (aka. deflate):
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> The driver constructs an array of addresses of memory pages
    it has previously given to the balloon, as described above.
    This descriptor is added to the deflateq.

  <span class="hl kwa">\item</span> If the VIRTIO_BALLOON_F_MUST_TELL_HOST feature is negotiated, the
    guest informs the device of pages before it uses them.

  <span class="hl kwa">\item</span> Otherwise, the guest MAY begin to re-use pages previously
    given to the balloon before the device has acknowledged their
    withdrawal<span class="hl kwa">\footnote</span><span class="hl opt">{</span>In this case, deflation advice is merely a courtesy.
<span class="hl opt">}</span>.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\item</span> In either case, once the device has completed the inflation or
  deflation, the driver updates <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span> to reflect the new number of pages in the balloon<span class="hl kwa">\footnote</span><span class="hl opt">{</span>As updates to device-specific configuration space are not atomic, this field
isn&apos;t particularly reliable, but can be used to diagnose buggy guests.
<span class="hl opt">}</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device Operation<span class="hl opt">}{</span>Device Types / Memory Balloon Device / Device Operation<span class="hl opt">}</span>
The driver SHOULD supply pages to the balloon when <span class="hl kwa">\field</span><span class="hl opt">{</span>num_pages<span class="hl opt">}</span> is
greater than <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span>.

The driver MAY use pages from the balloon when <span class="hl kwa">\field</span><span class="hl opt">{</span>num_pages<span class="hl opt">}</span> is
less than <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span>.

The driver MUST use the deflateq to inform the device of pages that it
wants to use from the balloon.

If the VIRTIO_BALLOON_F_MUST_TELL_HOST feature is negotiated, the
driver MUST wait until the device has used the deflateq descriptor
before using the pages.

The driver MUST update <span class="hl kwa">\field</span><span class="hl opt">{</span>actual<span class="hl opt">}</span> after changing the number
of pages in the balloon.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Memory Statistics<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device Operation / Memory Statistics<span class="hl opt">}</span>

The stats virtqueue is atypical because communication is driven
by the device (not the driver). The channel becomes active at
driver initialization time when the driver adds an empty buffer
and notifies the device. A request for memory statistics proceeds
as follows:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>
<span class="hl kwa">\item</span> The device pushes the buffer onto the used ring and sends an
  interrupt.

<span class="hl kwa">\item</span> The driver pops the used buffer and discards it.

<span class="hl kwa">\item</span> The driver collects memory statistics and writes them into a
  new buffer.

<span class="hl kwa">\item</span> The driver adds the buffer to the virtqueue and notifies the
  device.

<span class="hl kwa">\item</span> The device pops the buffer (retaining it to initiate a
  subsequent request) and consumes the statistics.
<span class="hl kwa">\end</span><span class="hl opt">{</span>enumerate<span class="hl opt">}</span>

  Each statistic consists of a <span class="hl num">16</span> bit
  tag and a <span class="hl num">64</span> bit value. All statistics are optional and the
  driver chooses which ones to supply. To guarantee backwards
  compatibility, the driver SHOULD omit unsupported statistics.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_balloon_stat <span class="hl opt">{</span>
#define VIRTIO_BALLOON_S_SWAP_IN  <span class="hl num">0</span>
#define VIRTIO_BALLOON_S_SWAP_OUT <span class="hl num">1</span>
#define VIRTIO_BALLOON_S_MAJFLT   <span class="hl num">2</span>
#define VIRTIO_BALLOON_S_MINFLT   <span class="hl num">3</span>
#define VIRTIO_BALLOON_S_MEMFREE  <span class="hl num">4</span>
#define VIRTIO_BALLOON_S_MEMTOT   <span class="hl num">5</span>
        u16 tag;
        u64 val;
<span class="hl opt">}</span> __attribute__((packed));
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interface: Memory Statistics<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device Operation / Memory Statistics / Legacy Interface: Memory Statistics<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_balloon_stat
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Memory Statistics Tags<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / Memory Balloon Device / Device Operation / Memory Statistics Tags<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_SWAP_IN (<span class="hl num">0</span>)<span class="hl opt">]</span> The amount of memory that has been
  swapped in (in bytes).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_SWAP_OUT (<span class="hl num">1</span>)<span class="hl opt">]</span> The amount of memory that has been
  swapped out to disk (in bytes).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_MAJFLT (<span class="hl num">2</span>)<span class="hl opt">]</span> The number of major page faults that
  have occurred.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_MINFLT (<span class="hl num">3</span>)<span class="hl opt">]</span> The number of minor page faults that
  have occurred.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_MEMFREE (<span class="hl num">4</span>)<span class="hl opt">]</span> The amount of memory not being used
  for any purpose (in bytes).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_BALLOON_S_MEMTOT (<span class="hl num">5</span>)<span class="hl opt">]</span> The total amount of memory available
  (in bytes).
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\section</span><span class="hl opt">{</span>SCSI Host Device<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device<span class="hl opt">}</span>

The virtio SCSI host device groups together one or more virtual
logical units (such as disks), and allows communicating to them
using the SCSI protocol. An instance of the device represents a
SCSI host to which many targets and LUNs are attached.

The virtio SCSI device services two kinds of requests:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> command requests for a logical unit;

<span class="hl kwa">\item</span> task management functions related to a logical unit, target or
  command.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

The device is also able to send out notifications about added and
removed logical units. Together, these capabilities provide a
SCSI transport protocol that uses virtqueues as the transfer
medium. In the transport protocol, the virtio driver acts as the
initiator, while the virtio SCSI host provides one or more
targets that receive and process the requests.

This section relies on definitions from <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SAM<span class="hl opt">]{</span>SAM<span class="hl opt">}</span>.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device ID<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device ID<span class="hl opt">}</span>
  <span class="hl num">8</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Virtqueues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Virtqueues<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">0</span><span class="hl opt">]</span> controlq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">1</span><span class="hl opt">]</span> eventq
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl num">2</span><span class="hl kwa">\ldots</span> n<span class="hl opt">]</span> request queues
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Feature bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Feature bits<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_F_INOUT (<span class="hl num">0</span>)<span class="hl opt">]</span> A single request can include both
    device-readable and device-writable data buffers.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_F_HOTPLUG (<span class="hl num">1</span>)<span class="hl opt">]</span> The host SHOULD enable reporting of
    hot-plug and hot-unplug events for LUNs and targets on the SCSI bus.
    The guest SHOULD handle hot-plug and hot-unplug events.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_F_CHANGE (<span class="hl num">2</span>)<span class="hl opt">]</span> The host will <span class="hl kwb">report</span> changes to LUN
    parameters via a VIRTIO_SCSI_T_PARAM_CHANGE event; the guest
    SHOULD handle them.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_F_T10_PI (<span class="hl num">3</span>)<span class="hl opt">]</span> The extended fields for T10 protection
    information (DIF/DIX) are included in the SCSI request header.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device configuration layout<span class="hl opt">}</span>

  All fields of this configuration are always available.

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_scsi_config <span class="hl opt">{</span>
        le32 num_queues;
        le32 seg_max;
        le32 max_sectors;
        le32 cmd_per_lun;
        le32 event_info_size;
        le32 sense_size;
        le32 cdb_size;
        le16 max_channel;
        le16 max_target;
        le32 max_lun;
<span class="hl opt">}</span>;
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>num_queues<span class="hl opt">}]</span> is the total number of request virtqueues exposed by
    the device. The driver MAY use only one request queue,
    or it can use more to achieve better performance.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>seg_max<span class="hl opt">}]</span> is the maximum number of segments that can be in a
    command. A bidirectional command can include <span class="hl kwa">\field</span><span class="hl opt">{</span>seg_max<span class="hl opt">}</span> input
    segments and <span class="hl kwa">\field</span><span class="hl opt">{</span>seg_max<span class="hl opt">}</span> output segments.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>max_sectors<span class="hl opt">}]</span> is a hint to the driver about the maximum transfer
    size to use.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cmd_per_lun<span class="hl opt">}]</span> is tells the driver the maximum number of
    linked commands it can send to one LUN.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>event_info_size<span class="hl opt">}]</span> is the maximum size that the device will fill
    for buffers that the driver places in the eventq. It is
    written by the device depending on the set of negotiated
    features.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>sense_size<span class="hl opt">}]</span> is the maximum size of the sense data that the
    device will write. The default value is written by the device
    and MUST be <span class="hl num">96</span>, but the driver can modify it. It is
    restored to the default when the device is reset.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>cdb_size<span class="hl opt">}]</span> is the maximum size of the CDB that the driver will
    write. The default value is written by the device and MUST
    be <span class="hl num">32</span>, but the driver can likewise modify it. It is
    restored to the default when the device is reset.

<span class="hl kwa">\item</span><span class="hl opt">[</span><span class="hl kwa">\field</span><span class="hl opt">{</span>max_channel<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>max_target<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>max_lun<span class="hl opt">}]</span> can be
    used by the driver as hints to constrain scanning the logical units
    on the host to channel/target/logical unit numbers that are less than
    or equal to the value of the fields.  <span class="hl kwa">\field</span><span class="hl opt">{</span>max_channel<span class="hl opt">}</span> SHOULD
    be zero.  <span class="hl kwa">\field</span><span class="hl opt">{</span>max_target<span class="hl opt">}</span> SHOULD be less than or equal to <span class="hl num">255</span>.
    <span class="hl kwa">\field</span><span class="hl opt">{</span>max_lun<span class="hl opt">}</span> SHOULD be less than or equal to <span class="hl num">16383</span>.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device configuration layout<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device configuration layout<span class="hl opt">}</span>

The driver MUST NOT write to device configuration fields other than
<span class="hl kwa">\field</span><span class="hl opt">{</span>sense_size<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>cdb_size<span class="hl opt">}</span>.

The driver MUST NOT send more than <span class="hl kwa">\field</span><span class="hl opt">{</span>cmd_per_lun<span class="hl opt">}</span> linked commands
to one LUN, and MUST NOT send more than the virtqueue size number of
linked commands to one LUN.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsubsection</span><span class="hl opt">}{</span>Device configuration layout<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device configuration layout<span class="hl opt">}</span>

On reset, the device MUST set <span class="hl kwa">\field</span><span class="hl opt">{</span>sense_size<span class="hl opt">}</span> to <span class="hl num">96</span> and
<span class="hl kwa">\field</span><span class="hl opt">{</span>cdb_size<span class="hl opt">}</span> to <span class="hl num">32</span>.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Device configuration layout<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device configuration layout / Legacy Interface: Device configuration layout<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_scsi_config
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\subsection</span><span class="hl opt">}{</span>Device Initialization<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device Initialization<span class="hl opt">}</span>

On initialization the driver SHOULD first discover the
device&apos;s virtqueues.

If the driver uses the eventq, the driver SHOULD place at least one
buffer in the eventq.

The driver MAY immediately issue requests<span class="hl kwa">\footnote</span><span class="hl opt">{</span>For example, INQUIRY
or REPORT LUNS.<span class="hl opt">}</span> or task management functions<span class="hl kwa">\footnote</span><span class="hl opt">{</span>For example, I_T
RESET.<span class="hl opt">}</span>.

<span class="hl kwa">\subsection</span><span class="hl opt">{</span>Device Operation<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation<span class="hl opt">}</span>

Device operation consists of operating request queues, the control
queue and the event queue.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Operation: Request Queues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: Request Queues<span class="hl opt">}</span>

The driver queues requests to an arbitrary request queue, and
they are used by the device on that same queue. It is the
responsibility of the driver to ensure strict request ordering
for commands placed on different queues, because they will be
consumed with no order constraints.

Requests have the following format:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_scsi_req_cmd <span class="hl opt">{</span>
        // Device-readable part
        u8 lun<span class="hl opt">[</span><span class="hl num">8</span><span class="hl opt">]</span>;
        le64 id;
        u8 task_attr;
        u8 prio;
        u8 crn;
        u8 cdb<span class="hl opt">[</span>cdb_size<span class="hl opt">]</span>;
        // The next two fields are only present if VIRTIO_SCSI_F_T10_PI
        // is negotiated.
        le32 pi_bytesout;
        le32 pi_bytesin;
        u8 pi_out<span class="hl opt">[</span>pi_bytesout<span class="hl opt">]</span>;
        u8 dataout<span class="hl opt">[]</span>;

        // Device-writable part
        le32 sense_len;
        le32 residual;
        le16 status_qualifier;
        u8 status;
        u8 response;
        u8 sense<span class="hl opt">[</span>sense_size<span class="hl opt">]</span>;
        // The next two fields are only present if VIRTIO_SCSI_F_T10_PI
        // is negotiated
        u8 pi_in<span class="hl opt">[</span>pi_bytesin<span class="hl opt">]</span>;
        u8 datain<span class="hl opt">[]</span>;
<span class="hl opt">}</span>;


/* command-specific response values */
#define VIRTIO_SCSI_S_OK                <span class="hl num">0</span>
#define VIRTIO_SCSI_S_OVERRUN           <span class="hl num">1</span>
#define VIRTIO_SCSI_S_ABORTED           <span class="hl num">2</span>
#define VIRTIO_SCSI_S_BAD_TARGET        <span class="hl num">3</span>
#define VIRTIO_SCSI_S_RESET             <span class="hl num">4</span>
#define VIRTIO_SCSI_S_BUSY              <span class="hl num">5</span>
#define VIRTIO_SCSI_S_TRANSPORT_FAILURE <span class="hl num">6</span>
#define VIRTIO_SCSI_S_TARGET_FAILURE    <span class="hl num">7</span>
#define VIRTIO_SCSI_S_NEXUS_FAILURE     <span class="hl num">8</span>
#define VIRTIO_SCSI_S_FAILURE           <span class="hl num">9</span>

/* task_attr */
#define VIRTIO_SCSI_S_SIMPLE            <span class="hl num">0</span>
#define VIRTIO_SCSI_S_ORDERED           <span class="hl num">1</span>
#define VIRTIO_SCSI_S_HEAD              <span class="hl num">2</span>
#define VIRTIO_SCSI_S_ACA               <span class="hl num">3</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> addresses the REPORT LUNS well-known logical unit, or
a target and logical unit in the virtio-scsi device&apos;s SCSI domain.
When used to address the REPORT LUNS logical unit, <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> is <span class="hl num">0xC1</span>,
<span class="hl num">0x01</span> and six zero bytes.  The virtio-scsi device SHOULD implement the
REPORT LUNS well-known logical unit.

When used to address a target and logical unit, the only supported format
for <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> is: first byte set to <span class="hl num">1</span>, second byte set to target,
third and fourth byte representing a single level LUN structure, followed
by four zero bytes. With this representation, a virtio-scsi device can
serve up to <span class="hl num">256</span> targets and <span class="hl num">16384</span> LUNs per target.  The device MAY also
support having a well-known logical units in the third and fourth byte.

<span class="hl kwa">\field</span><span class="hl opt">{</span>id<span class="hl opt">}</span> is the command identifier (``tag&apos;&apos;).

<span class="hl kwa">\field</span><span class="hl opt">{</span>task_attr<span class="hl opt">}</span> defines the task attribute as in the table above, but
all task attributes MAY be mapped to SIMPLE by the device.  Some commands
are defined by SCSI standards as &quot;implicit head of queue&quot;; for such
commands, all task attributes MAY also be mapped to HEAD OF QUEUE.
Drivers and applications SHOULD NOT send a command with the ORDERED
task attribute if the command has an implicit HEAD OF QUEUE attribute,
because whether the ORDERED task attribute is honored is vendor-specific.

<span class="hl kwa">\field</span><span class="hl opt">{</span>crn<span class="hl opt">}</span> may also be provided by clients, but is generally expected
to be <span class="hl num">0</span>. The maximum CRN value defined by the protocol is <span class="hl num">255</span>, since
CRN is stored in an <span class="hl num">8</span>-bit integer.

The CDB is included in <span class="hl kwa">\field</span><span class="hl opt">{</span>cdb<span class="hl opt">}</span> and its size, <span class="hl kwa">\field</span><span class="hl opt">{</span>cdb_size<span class="hl opt">}</span>,
is taken from the configuration space.

All of these fields are defined in <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SAM<span class="hl opt">]{</span>SAM<span class="hl opt">}</span> and are
always device-readable.

<span class="hl kwa">\field</span><span class="hl opt">{</span>pi_bytesout<span class="hl opt">}</span> determines the size of the <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_out<span class="hl opt">}</span> field
in bytes.  If it is nonzero, the <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_out<span class="hl opt">}</span> field contains outgoing
protection information for write operations.  <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_bytesin<span class="hl opt">}</span> determines
the size of the <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_in<span class="hl opt">}</span> field in the device-writable section, in bytes.
All three fields are only present if VIRTIO_SCSI_F_T10_PI has been negotiated.

The remainder of the device-readable part is the data output buffer,
<span class="hl kwa">\field</span><span class="hl opt">{</span>dataout<span class="hl opt">}</span>.

<span class="hl kwa">\field</span><span class="hl opt">{</span>sense<span class="hl opt">}</span> and subsequent fields are always device-writable. <span class="hl kwa">\field</span><span class="hl opt">{</span>sense_len<span class="hl opt">}</span>
indicates the number of bytes actually written to the sense
buffer.

<span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> indicates the residual size,
calculated as ``data_length - number_of_transferred_bytes&apos;&apos;, for
read or write operations. For bidirectional commands, the
number_of_transferred_bytes includes both read and written bytes.
A <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> that is less than the size of <span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span> means that
<span class="hl kwa">\field</span><span class="hl opt">{</span>dataout<span class="hl opt">}</span> was processed entirely. A <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> that
exceeds the size of <span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span> means that <span class="hl kwa">\field</span><span class="hl opt">{</span>dataout<span class="hl opt">}</span> was
processed partially and <span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span> was not processed at
all.

If the <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_bytesin<span class="hl opt">}</span> is nonzero, the <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_in<span class="hl opt">}</span> field contains
incoming protection information for read operations.  <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_in<span class="hl opt">}</span> is
only present if VIRTIO_SCSI_F_T10_PI has been negotiated<span class="hl kwa">\footnote</span><span class="hl opt">{</span>There
  is no separate residual size for <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_bytesout<span class="hl opt">}</span> and
  <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_bytesin<span class="hl opt">}</span>.  It can be computed from the <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span> field,
  the size of the data integrity information per sector, and the sizes
  of <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_out<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>pi_in<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>dataout<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span>.<span class="hl opt">}</span>.

The remainder of the device-writable part is the data input buffer,
<span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span>.


<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device Operation: Request Queues<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device Operation / Device Operation: Request Queues<span class="hl opt">}</span>

The device MUST write the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span> byte as the status code as
defined in <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SAM<span class="hl opt">]{</span>SAM<span class="hl opt">}</span>.

The device MUST write the <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span> byte as one of the following:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_OK<span class="hl opt">]</span> when the request was completed and the <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>
  byte is filled with a SCSI status code (not necessarily
  ``GOOD&apos;&apos;).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_OVERRUN<span class="hl opt">]</span> if the content of the CDB (such as the
  allocation length, parameter length or transfer size) requires
  more data than is available in the datain and dataout buffers.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_ABORTED<span class="hl opt">]</span> if the request was cancelled due to an
  ABORT TASK or ABORT TASK SET task management function.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_BAD_TARGET<span class="hl opt">]</span> if the request was never processed
  because the target indicated by <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> does not exist.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_RESET<span class="hl opt">]</span> if the request was cancelled due to a bus
  or device reset (including a task management function).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_TRANSPORT_FAILURE<span class="hl opt">]</span> if the request failed due to a
  problem in the connection between the host and the target
  (severed link).

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_TARGET_FAILURE<span class="hl opt">]</span> if the target is suffering a
  failure and to tell the driver not to retry on other paths.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_NEXUS_FAILURE<span class="hl opt">]</span> if the nexus is suffering a failure
  but retrying on other paths might yield a different result.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_BUSY<span class="hl opt">]</span> if the request failed but retrying on the
  same path is likely to work.

<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_S_FAILURE<span class="hl opt">]</span> for other host or driver error. In
  particular, if neither <span class="hl kwa">\field</span><span class="hl opt">{</span>dataout<span class="hl opt">}</span> nor <span class="hl kwa">\field</span><span class="hl opt">{</span>datain<span class="hl opt">}</span> is empty, and the
  VIRTIO_SCSI_F_INOUT feature has not been negotiated, the
  request will be immediately returned with a response equal to
  VIRTIO_SCSI_S_FAILURE.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

All commands must be completed before the virtio-scsi device is
reset or unplugged.  The device MAY choose to abort them, or if
it does not do so MUST pick the VIRTIO_SCSI_S_FAILURE response.

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device Operation: Request Queues<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device Operation / Device Operation: Request Queues<span class="hl opt">}</span>

<span class="hl kwa">\field</span><span class="hl opt">{</span>task_attr<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>prio<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>crn<span class="hl opt">}</span> SHOULD be zero.

Upon receiving a VIRTIO_SCSI_S_TARGET_FAILURE response, the driver
SHOULD NOT retry the request on other paths.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interface: Device Operation: Request Queues<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: Request Queues / Legacy Interface: Device Operation: Request Queues<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_scsi_req_cmd
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Operation: controlq<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: controlq<span class="hl opt">}</span>

The controlq is used for other SCSI transport operations.
Requests have the following format:

<span class="hl opt">{</span>
<span class="hl kwa">\lstset</span><span class="hl opt">{</span>escapechar=\$<span class="hl opt">}</span>
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
struct virtio_scsi_ctrl <span class="hl opt">{</span>
        le32 type;
$<span class="hl kwa">\ldots</span>$
        u8 response;
<span class="hl opt">}</span>;

/* response values valid for all commands */
#define VIRTIO_SCSI_S_OK                       <span class="hl num">0</span>
#define VIRTIO_SCSI_S_BAD_TARGET               <span class="hl num">3</span>
#define VIRTIO_SCSI_S_BUSY                     <span class="hl num">5</span>
#define VIRTIO_SCSI_S_TRANSPORT_FAILURE        <span class="hl num">6</span>
#define VIRTIO_SCSI_S_TARGET_FAILURE           <span class="hl num">7</span>
#define VIRTIO_SCSI_S_NEXUS_FAILURE            <span class="hl num">8</span>
#define VIRTIO_SCSI_S_FAILURE                  <span class="hl num">9</span>
#define VIRTIO_SCSI_S_INCORRECT_LUN            <span class="hl num">12</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
<span class="hl opt">}</span>

The <span class="hl kwa">\field</span><span class="hl opt">{</span>type<span class="hl opt">}</span> identifies the remaining fields.

The following commands are defined:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> Task management function.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_TMF                      <span class="hl num">0</span>

#define VIRTIO_SCSI_T_TMF_ABORT_TASK           <span class="hl num">0</span>
#define VIRTIO_SCSI_T_TMF_ABORT_TASK_SET       <span class="hl num">1</span>
#define VIRTIO_SCSI_T_TMF_CLEAR_ACA            <span class="hl num">2</span>
#define VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET       <span class="hl num">3</span>
#define VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET      <span class="hl num">4</span>
#define VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET   <span class="hl num">5</span>
#define VIRTIO_SCSI_T_TMF_QUERY_TASK           <span class="hl num">6</span>
#define VIRTIO_SCSI_T_TMF_QUERY_TASK_SET       <span class="hl num">7</span>

struct virtio_scsi_ctrl_tmf
<span class="hl opt">{</span>
        // Device-readable part
        le32 type;
        le32 subtype;
        u8   lun<span class="hl opt">[</span><span class="hl num">8</span><span class="hl opt">]</span>;
        le64 id;
        // Device-writable part
        u8   response;
<span class="hl opt">}</span>

/* command-specific response values */
#define VIRTIO_SCSI_S_FUNCTION_COMPLETE        <span class="hl num">0</span>
#define VIRTIO_SCSI_S_FUNCTION_SUCCEEDED       <span class="hl num">10</span>
#define VIRTIO_SCSI_S_FUNCTION_REJECTED        <span class="hl num">11</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  The <span class="hl kwa">\field</span><span class="hl opt">{</span>type<span class="hl opt">}</span> is VIRTIO_SCSI_T_TMF; <span class="hl kwa">\field</span><span class="hl opt">{</span>subtype<span class="hl opt">}</span> defines which
  task management function. All
  fields except <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span> are filled by the driver.

  Other fields which are irrelevant for the requested TMF
  are ignored but they are still present. <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span>
  is in the same format specified for request queues; the
  single level LUN is ignored when the task management function
  addresses a whole I_T nexus. When relevant, the value of <span class="hl kwa">\field</span><span class="hl opt">{</span>id<span class="hl opt">}</span>
  is matched against the id values passed on the requestq.

  The outcome of the task management function is written by the
  device in <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span>. The command-specific response
  values map <span class="hl num">1</span>-to-<span class="hl num">1</span> with those defined in <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SAM<span class="hl opt">]{</span>SAM<span class="hl opt">}</span>.

  Task management function can affect the response value for commands that
  are in the request queue and have not been completed yet.  For example,
  the device MUST complete all active commands on a logical unit
  or target (possibly with a VIRTIO_SCSI_S_RESET response code)
  upon receiving a &quot;logical unit reset&quot; or &quot;I_T nexus reset&quot; TMF.
  Similarly, the device MUST complete the selected commands (possibly
  with a VIRTIO_SCSI_S_ABORTED response code) upon receiving an &quot;abort
  task&quot; or &quot;abort task set&quot; TMF.  Such effects MUST take place before
  the TMF itself is successfully completed, and the device MUST use
  memory barriers appropriately in order to ensure that the driver sees
  these writes in the correct order.

<span class="hl kwa">\item</span> Asynchronous notification query.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_AN_QUERY                    <span class="hl num">1</span>

struct virtio_scsi_ctrl_an <span class="hl opt">{</span>
    // Device-readable part
    le32 type;
    u8   lun<span class="hl opt">[</span><span class="hl num">8</span><span class="hl opt">]</span>;
    le32 event_requested;
    // Device-writable part
    le32 event_actual;
    u8   response;
<span class="hl opt">}</span>

#define VIRTIO_SCSI_EVT_ASYNC_OPERATIONAL_CHANGE  <span class="hl num">2</span>
#define VIRTIO_SCSI_EVT_ASYNC_POWER_MGMT          <span class="hl num">4</span>
#define VIRTIO_SCSI_EVT_ASYNC_EXTERNAL_REQUEST    <span class="hl num">8</span>
#define VIRTIO_SCSI_EVT_ASYNC_MEDIA_CHANGE        <span class="hl num">16</span>
#define VIRTIO_SCSI_EVT_ASYNC_MULTI_HOST          <span class="hl num">32</span>
#define VIRTIO_SCSI_EVT_ASYNC_DEVICE_BUSY         <span class="hl num">64</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  By sending this command, the driver asks the device which
  events the given LUN can <span class="hl kwb">report</span>, as described in paragraphs <span class="hl num">6.6</span>
  and A<span class="hl num">.6</span> of <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SCSI MMC<span class="hl opt">]{</span>SCSI MMC<span class="hl opt">}</span>. The driver writes the
  events it is interested in into <span class="hl kwa">\field</span><span class="hl opt">{</span>event_requested<span class="hl opt">}</span>; the device
  responds by writing the events that it supports into
  <span class="hl kwa">\field</span><span class="hl opt">{</span>event_actual<span class="hl opt">}</span>.

  The <span class="hl kwa">\field</span><span class="hl opt">{</span>type<span class="hl opt">}</span> is VIRTIO_SCSI_T_AN_QUERY. <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>event_requested<span class="hl opt">}</span>
  are written by the driver. <span class="hl kwa">\field</span><span class="hl opt">{</span>event_actual<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span>
  fields are written by the device.

  No command-specific values are defined for the <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span> byte.

<span class="hl kwa">\item</span> Asynchronous notification subscription.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_AN_SUBSCRIBE                <span class="hl num">2</span>

struct virtio_scsi_ctrl_an <span class="hl opt">{</span>
        // Device-readable part
        le32 type;
        u8   lun<span class="hl opt">[</span><span class="hl num">8</span><span class="hl opt">]</span>;
        le32 event_requested;
        // Device-writable part
        le32 event_actual;
        u8   response;
<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  By sending this command, the driver asks the specified LUN to
  <span class="hl kwb">report</span> events for its physical interface, again as described in
   <span class="hl kwa">\hyperref</span><span class="hl opt">[</span>intro:SCSI MMC<span class="hl opt">]{</span>SCSI MMC<span class="hl opt">}</span>. The driver writes the events it is
  interested in into <span class="hl kwa">\field</span><span class="hl opt">{</span>event_requested<span class="hl opt">}</span>; the device responds by
  writing the events that it supports into <span class="hl kwa">\field</span><span class="hl opt">{</span>event_actual<span class="hl opt">}</span>.

  Event types are the same as for the asynchronous notification
  query message.

  The <span class="hl kwa">\field</span><span class="hl opt">{</span>type<span class="hl opt">}</span> is VIRTIO_SCSI_T_AN_SUBSCRIBE. <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> and
  <span class="hl kwa">\field</span><span class="hl opt">{</span>event_requested<span class="hl opt">}</span> are written by the driver.
  <span class="hl kwa">\field</span><span class="hl opt">{</span>event_actual<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span> are written by the device.

  No command-specific values are defined for the response byte.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interface: Device Operation: controlq<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: controlq / Legacy Interface: Device Operation: controlq<span class="hl opt">}</span>

When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_scsi_ctrl, struct
virtio_scsi_ctrl_tmf, struct virtio_scsi_ctrl_an and struct
virtio_scsi_ctrl_an
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.


<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Device Operation: eventq<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: eventq<span class="hl opt">}</span>

The eventq is populated by the driver for the device to <span class="hl kwb">report</span> information on logical
units that are attached to it. In general, the device will not
queue events to cope with an empty eventq, and will end up
dropping events if it finds no buffer ready. However, when
reporting events for many LUNs (e.g. when a whole target
disappears), the device can throttle events to avoid dropping
them. For this reason, placing <span class="hl num">10</span>-<span class="hl num">15</span> buffers on the event queue
is sufficient.

Buffers returned by the device on the eventq will be referred to
as ``events&apos;&apos; in the rest of this section. Events have the
following format:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_EVENTS_MISSED   <span class="hl num">0x80000000</span>

struct virtio_scsi_event <span class="hl opt">{</span>
        // Device-writable part
        le32 event;
        u8  lun<span class="hl opt">[</span><span class="hl num">8</span><span class="hl opt">]</span>;
        le32 reason;
<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

The devices sets bit <span class="hl num">31</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> to <span class="hl kwb">report</span> lost events
due to missing buffers.

The meaning of <span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> depends on the
contents of <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span>. The following events are defined:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> No event.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_NO_EVENT         <span class="hl num">0</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  This event is fired in the following cases:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
<span class="hl kwa">\item</span> When the device detects in the eventq a buffer that is
    shorter than what is indicated in the configuration field, it
    MAY use it immediately and put this dummy value in <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span>.
    A well-written driver will never observe this
    situation.

<span class="hl kwa">\item</span> When events are dropped, the device MAY signal this event as
    soon as the drivers makes a buffer available, in order to
    request action from the driver. In this case, of course, this
    event will be reported with the VIRTIO_SCSI_T_EVENTS_MISSED
    flag.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\item</span> Transport reset
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_TRANSPORT_RESET  <span class="hl num">1</span>

#define VIRTIO_SCSI_EVT_RESET_HARD         <span class="hl num">0</span>
#define VIRTIO_SCSI_EVT_RESET_RESCAN       <span class="hl num">1</span>
#define VIRTIO_SCSI_EVT_RESET_REMOVED      <span class="hl num">2</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  By sending this event, the device signals that a logical unit
  on a target has been reset, including the case of a new device
  appearing or disappearing on the bus. The device fills in all
  fields. <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> is set to
  VIRTIO_SCSI_T_TRANSPORT_RESET. <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> addresses a
  logical unit in the SCSI host.

  The <span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> value is one of the three \#define values appearing
  above:

  <span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_EVT_RESET_REMOVED<span class="hl opt">]</span> (``LUN/target removed&apos;&apos;) is used
    if the target or logical unit is no longer able to receive
    commands.

  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_EVT_RESET_HARD<span class="hl opt">]</span> (``LUN hard reset&apos;&apos;) is used if the
    logical unit has been reset, but is still present.

  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_SCSI_EVT_RESET_RESCAN<span class="hl opt">]</span> (``rescan LUN/target&apos;&apos;) is used if
    a target or logical unit has just appeared on the device.
  <span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

  The ``removed&apos;&apos; and ``rescan&apos;&apos; events can happen when
  VIRTIO_SCSI_F_HOTPLUG feature was negotiated; when sent for LUN <span class="hl num">0</span>,
  they MAY apply to the entire target so the driver can ask the
  initiator to rescan the target to detect this.

  Events will also be reported via sense codes (this obviously
  does not apply to newly appeared buses or targets, since the
  application has never discovered them):

  <span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
  <span class="hl kwa">\item</span> ``LUN/target removed&apos;&apos; maps to sense key ILLEGAL REQUEST, asc
    <span class="hl num">0x25</span>, ascq <span class="hl num">0x00</span> (LOGICAL UNIT NOT SUPPORTED)

  <span class="hl kwa">\item</span> ``LUN hard reset&apos;&apos; maps to sense key UNIT ATTENTION, asc <span class="hl num">0x29</span>
    (POWER ON, RESET OR BUS DEVICE RESET OCCURRED)

  <span class="hl kwa">\item</span> ``rescan LUN/target&apos;&apos; maps to sense key UNIT ATTENTION, asc
    <span class="hl num">0x3f</span>, ascq <span class="hl num">0x0e</span> (REPORTED LUNS DATA HAS CHANGED)
  <span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

  The preferred way to detect transport reset is always to use
  events, because sense codes are only seen by the driver when it
  sends a SCSI command to the logical unit or target. However, in
  case events are dropped, the initiator will still be able to
  synchronize with the actual state of the controller if the
  driver asks the initiator to rescan of the SCSI bus. During the
  rescan, the initiator will be able to observe the above sense
  codes, and it will process them as if it the driver had
  received the equivalent event.

  <span class="hl kwa">\item</span> Asynchronous notification
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_ASYNC_NOTIFY     <span class="hl num">2</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  By sending this event, the device signals that an asynchronous
  event was fired from a physical interface.

  All fields are written by the device. <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> is set to
  VIRTIO_SCSI_T_ASYNC_NOTIFY. <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> addresses a logical
  unit in the SCSI host. <span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> is a subset of the
  events that the driver has subscribed to via the ``Asynchronous
  notification subscription&apos;&apos; command.

  <span class="hl kwa">\item</span> LUN parameter change
<span class="hl kwa">\begin</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>
#define VIRTIO_SCSI_T_PARAM_CHANGE  <span class="hl num">3</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>lstlisting<span class="hl opt">}</span>

  By sending this event, the device signals a change in the configuration parameters
  of a logical unit, for example the capacity or caching mode.
  <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> is set to VIRTIO_SCSI_T_PARAM_CHANGE.
  <span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span> addresses a logical unit in the SCSI host.

  The same event SHOULD also be reported as a unit attention condition.
  <span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> contains the additional sense code and additional sense code qualifier,
  respectively in bits <span class="hl num">0</span><span class="hl kwa">\ldots</span> <span class="hl num">7</span> and <span class="hl num">8</span><span class="hl kwa">\ldots</span> <span class="hl num">15</span>.
  <span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  For example, a change in capacity will be reported as asc <span class="hl num">0x2a</span>, ascq <span class="hl num">0x09</span>
  (CAPACITY DATA HAS CHANGED).
  <span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>

  For MMC devices (inquiry type <span class="hl num">5</span>) there would be some overlap between this
  event and the asynchronous notification event, so for simplicity the host never
  reports this event for MMC devices.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device Operation: eventq<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device Operation / Device Operation: eventq<span class="hl opt">}</span>

The driver SHOULD keep the eventq populated with buffers.  These
buffers MUST be device-writable, and SHOULD be at least
<span class="hl kwa">\field</span><span class="hl opt">{</span>event_info_size<span class="hl opt">}</span> bytes long, and MUST be at least the size of
struct virtio_scsi_event.

If <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> has bit <span class="hl num">31</span> set, the driver SHOULD
poll the logical units for unit attention conditions, and/or do
whatever form of bus scan is appropriate for the guest operating
system and SHOULD poll for asynchronous events manually using SCSI commands.

When receiving a VIRTIO_SCSI_T_TRANSPORT_RESET message with
<span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> set to VIRTIO_SCSI_EVT_RESET_REMOVED or
VIRTIO_SCSI_EVT_RESET_RESCAN for LUN <span class="hl num">0</span>, the driver SHOULD ask the
initiator to rescan the target, in order to detect the case when an
entire target has appeared or disappeared.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\paragraph</span><span class="hl opt">}{</span>Device Operation: eventq<span class="hl opt">}{</span>Device Types / SCSI Host Device / Device Operation / Device Operation: eventq<span class="hl opt">}</span>

The device MUST set bit <span class="hl num">31</span> in <span class="hl kwa">\field</span><span class="hl opt">{</span>event<span class="hl opt">}</span> if events were lost due to
missing buffers, and it MAY use a VIRTIO_SCSI_T_NO_EVENT event to <span class="hl kwb">report</span>
this.

The device MUST NOT send VIRTIO_SCSI_T_TRANSPORT_RESET messages
with <span class="hl kwa">\field</span><span class="hl opt">{</span>reason<span class="hl opt">}</span> set to VIRTIO_SCSI_EVT_RESET_REMOVED or
VIRTIO_SCSI_EVT_RESET_RESCAN unless VIRTIO_SCSI_F_HOTPLUG was negotiated.

The device MUST NOT <span class="hl kwb">report</span> VIRTIO_SCSI_T_PARAM_CHANGE for MMC devices.

<span class="hl kwa">\paragraph</span><span class="hl opt">{</span>Legacy Interface: Device Operation: eventq<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device Types / SCSI Host Device / Device Operation / Device Operation: eventq / Legacy Interface: Device Operation: eventq<span class="hl opt">}</span>
When using the legacy interface, transitional devices and drivers
MUST format the fields in struct virtio_scsi_event
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.

<span class="hl kwa">\subsubsection</span><span class="hl opt">{</span>Legacy Interface: Framing Requirements<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Device
Types / SCSI Host Device / Legacy Interface: Framing Requirements<span class="hl opt">}</span>

When using legacy interfaces, transitional drivers which have not
negotiated VIRTIO_F_ANY_LAYOUT MUST use a single descriptor for the
<span class="hl kwa">\field</span><span class="hl opt">{</span>lun<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>id<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>task_attr<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>prio<span class="hl opt">}</span>,
<span class="hl kwa">\field</span><span class="hl opt">{</span>crn<span class="hl opt">}</span> and <span class="hl kwa">\field</span><span class="hl opt">{</span>cdb<span class="hl opt">}</span> fields, and MUST only use a single
descriptor for the <span class="hl kwa">\field</span><span class="hl opt">{</span>sense_len<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>residual<span class="hl opt">}</span>,
<span class="hl kwa">\field</span><span class="hl opt">{</span>status_qualifier<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>status<span class="hl opt">}</span>, <span class="hl kwa">\field</span><span class="hl opt">{</span>response<span class="hl opt">}</span> and
<span class="hl kwa">\field</span><span class="hl opt">{</span>sense<span class="hl opt">}</span> fields.

<span class="hl kwa">\chapter</span><span class="hl opt">{</span>Reserved Feature Bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Reserved Feature Bits<span class="hl opt">}</span>

Currently there are three device-independent feature bits defined:

<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_F_RING_INDIRECT_DESC (<span class="hl num">28</span>)<span class="hl opt">]</span> Negotiating this feature indicates
  that the driver can use descriptors with the VIRTQ_DESC_F_INDIRECT
  flag set, as described in <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors<span class="hl opt">}</span>.

  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_F_RING_EVENT_IDX(<span class="hl num">29</span>)<span class="hl opt">]</span> This feature enables the <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span>
  and the <span class="hl kwa">\field</span><span class="hl opt">{</span>avail_event<span class="hl opt">}</span> fields as described in <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression<span class="hl opt">}</span> and <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring<span class="hl opt">}</span>.

  <span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_F_VERSION_1(<span class="hl num">32</span>)<span class="hl opt">]</span> This indicates compliance with this
    specification, giving a simple way to detect legacy devices or drivers.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

<span class="hl kwa">\drivernormative</span><span class="hl opt">{</span><span class="hl kwa">\section</span><span class="hl opt">}{</span>Reserved Feature Bits<span class="hl opt">}{</span>Reserved Feature Bits<span class="hl opt">}</span>

A driver MUST accept VIRTIO_F_VERSION_1 if it is offered.  A driver
MAY fail to operate further if VIRTIO_F_VERSION_1 is not offered.

<span class="hl kwa">\devicenormative</span><span class="hl opt">{</span><span class="hl kwa">\section</span><span class="hl opt">}{</span>Reserved Feature Bits<span class="hl opt">}{</span>Reserved Feature Bits<span class="hl opt">}</span>

A device MUST offer VIRTIO_F_VERSION_1.  A device MAY fail to operate further
if VIRTIO_F_VERSION_1 is not accepted.

<span class="hl kwa">\section</span><span class="hl opt">{</span>Legacy Interface: Reserved Feature Bits<span class="hl opt">}</span><span class="hl kwa">\label</span><span class="hl opt">{</span>sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits<span class="hl opt">}</span>

Transitional devices MAY offer the following:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_F_NOTIFY_ON_EMPTY (<span class="hl num">24</span>)<span class="hl opt">]</span> If this feature
  has been negotiated by driver, the device MUST issue
  an interrupt if the device runs
  out of available descriptors on a virtqueue, even though
  interrupts are suppressed using the VIRTQ_AVAIL_F_NO_INTERRUPT
  flag or the <span class="hl kwa">\field</span><span class="hl opt">{</span>used_event<span class="hl opt">}</span> field.
<span class="hl kwa">\begin</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
  An example of a driver using this feature is the legacy
  networking driver: it doesn&apos;t need to know every time a packet
  is transmitted, but it does need to free the transmitted
  packets a finite time after they are transmitted. It can avoid
  using a timer if the device interrupts it when all the packets
  are transmitted.
<span class="hl kwa">\end</span><span class="hl opt">{</span>note<span class="hl opt">}</span>
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

Transitional devices MUST offer, and if offered by the device
transitional drivers MUST accept the following:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>VIRTIO_F_ANY_LAYOUT (<span class="hl num">27</span>)<span class="hl opt">]</span> This feature indicates that the device
  accepts arbitrary descriptor layouts, as described in Section
  <span class="hl kwa">\ref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing<span class="hl opt">}</span>~<span class="hl kwa">\nameref</span><span class="hl opt">{</span>sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing<span class="hl opt">}</span>.

<span class="hl kwa">\item</span><span class="hl opt">[</span>UNUSED (<span class="hl num">30</span>)<span class="hl opt">]</span> Bit <span class="hl num">30</span> is used by qemu&apos;s implementation to check
  for experimental early versions of virtio which did not perform
  correct feature negotiation, and SHOULD NOT be negotiated.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
</code></pre></td></tr></table>
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