[PATCH] split-ring: Demand that a device must not change descriptor entries

[Jan Kiszka <jan.kiszka@siemens.com>]

From: Jan Kiszka <jan.kiszka@siemens.com>

So far the spec only indirectly says that a descriptor table entry is
not modified by a device when processing it. Make this explicit by
adding it as normative requirement. Existing drivers already depend on
this.

See also https://lists.oasis-open.org/archives/virtio-dev/201910/msg00057.html.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 split-ring.tex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/split-ring.tex b/split-ring.tex
index 123ac9f..bfef62d 100644
--- a/split-ring.tex
+++ b/split-ring.tex
@@ -217,7 +217,7 @@ \subsection{The Virtqueue Descriptor Table}\label{sec:Basic Facilities of a Virt
 \devicenormative{\subsubsection}{The Virtqueue Descriptor Table}{Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table}
 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).
+purposes). A device MUST NOT write to any descriptor table entry.
 
 \drivernormative{\subsubsection}{The Virtqueue Descriptor Table}{Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table}
 Drivers MUST NOT add a descriptor chain longer than $2^{32}$ bytes in total;
-- 
2.16.4