[PATCH v10 07/10] ccw: document ADMIN_VQ as reserved

["Michael S. Tsirkin" <mst@redhat.com>]

Adding relevant registers needs more work and it's not
clear what the use-case will be as currently only
the PCI transport is supported. But let's keep the
door open on this.
We already say it's reserved in a central place, but it
does not hurt to remind implementers to mask it.

Note: there are more features to add to this list.
Will be done later with a patch on top.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 content.tex | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/content.tex b/content.tex
index f8bd1ab..6a50b39 100644
--- a/content.tex
+++ b/content.tex
@@ -2976,6 +2976,18 @@ \subsubsection{Resetting Devices}\label{sec:Virtio Transport Options / Virtio ov
 MAY also choose to verify reset completion by reading \field{device status} via
 CCW_CMD_READ_STATUS and checking whether it is 0 afterwards.
 
+\subsection{Features reserved for future use}\label{sec:Virtio Transport Options / Virtio over channel I/O / Features reserved for future use}
+
+At this time, devices and drivers utilizing Virtio over channel I/O
+do not support the following features:
+\begin{itemize}
+
+\item VIRTIO_F_ADMIN_VQ
+
+\end{itemize}
+
+These features are reserved for future use.
+
 \chapter{Device Types}\label{sec:Device Types}
 
 On top of the queues, config space and feature negotiation facilities
-- 
MST