[PATCH 2/4] ccw: clarify scope of the revision

[Cornelia Huck <cornelia.huck@de.ibm.com>]

The revision selected by the SET_VIRTIO_REV command specifies which
commands are accepted by the device, regardless whether the VERSION_1
feature bit has been negotiated or not. As the revision needs to be
negotiated before feature bits can be negotiated, anything else would
be inconsistent.

VIRTIO-119

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 content.tex |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/content.tex b/content.tex
index ca5bd5c..6968583 100644
--- a/content.tex
+++ b/content.tex
@@ -2493,6 +2493,11 @@ The following values are supported:
 Note that a change in the virtio standard does not necessarily
 correspond to a change in the virtio-ccw revision.
 
+Also note that the different commands are bound to the virtio-ccw revision,
+not to any virtio feature bits: For example, if the driver negotiated
+revision 1 but not VIRTIO_F_VERSION_1, it is free to use any command from
+revision 1.
+
 \devicenormative{\paragraph}{Setting the Virtio Revision}{Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision}
 
 A device MUST post a unit check with command reject for any \field{revision}
-- 
1.7.9.5