From aa9778215ce3bf31de1c8e8903f303c31eee9c31 Mon Sep 17 00:00:00 2001
From: rusty <rusty@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>
Date: Mon, 12 May 2014 01:57:36 +0000
Subject: VIRTIO-87: limit descriptor chain length even with INDIRECT.

As passed at meeting 2014-05-06:
        https://lists.oasis-open.org/archives/virtio/201405/msg00016.html

Signed-off-by: Rusty Russell <rusty@au1.ibm.com>

git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio@366 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652
---
 content.tex | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'content.tex')

diff --git a/content.tex b/content.tex
index 4525975..83d1afd 100644
--- a/content.tex
+++ b/content.tex
@@ -404,7 +404,7 @@ struct virtq_desc {
 \end{lstlisting}
 
 The number of descriptors in the table is defined by the queue size
-for this virtqueue.
+for this virtqueue: this is the maximum possible descriptor chain length.
 
 \begin{note}
 The legacy \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}
@@ -456,6 +456,9 @@ 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.
+
 \devicenormative{\paragraph}{Indirect Descriptors}{Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors}
 The device MUST ignore the write-only flag (\field{flags}\&VIRTQ_DESC_F_WRITE) in the descriptor that refers to an indirect table.
 
-- 
cgit v1.2.3

