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authormstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2014-03-02 21:35:34 +0000
committermstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2014-03-02 21:35:34 +0000
commit6c55d867ebbac11da6e16323fd4b7b2e386f329f (patch)
treecca38182d4b1858c2d6b6ce5a889dcc8d5b4c6fb
parentea07d76b67881e6126b4bb3bf10541f83deeea5e (diff)
legacy feature bits: confirmance statements
Change accepted on VIRTIO TC Meeting, 3 December 2013 Signed-off-by: Michael S. Tsirkin <mst@redhat.com> git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio@296 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652
-rw-r--r--content.tex14
1 files changed, 9 insertions, 5 deletions
diff --git a/content.tex b/content.tex
index 20a61d6..d6cafc6 100644
--- a/content.tex
+++ b/content.tex
@@ -4787,23 +4787,27 @@ if VIRTIO_F_VERSION_1 is not accepted.
\section{Legacy Interface: Reserved Feature Bits}\label{sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits}
-Legacy or transitional devices may offer the following:
-
+Transitional devices MAY offer the following:
\begin{description}
-\item[VIRTIO_F_NOTIFY_ON_EMPTY (24)] Negotiating this feature
- indicates that the driver wants an interrupt if the device runs
+\item[VIRTIO_F_NOTIFY_ON_EMPTY (24)] 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 VRING_AVAIL_F_NO_INTERRUPT
flag or the \field{used_event} field.
\begin{note}
- An example of this is the
+ An example of a driver using this feature is the legacy
networking driver: it doesn'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.
\end{note}
+\end{description}
+Transitional devices MUST offer, and if offered by the device
+traditional drivers MUST negotiate the following:
+\begin{description}
\item[VIRTIO_F_ANY_LAYOUT (27)] This feature indicates that the device
accepts arbitrary descriptor layouts, as described in Section
\ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing}.