[PATCH 09/14] legacy feature bits: confirmance statements

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

---
 content.tex | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/content.tex b/content.tex
index 2de0644..58402f3 100644
--- a/content.tex
+++ b/content.tex
@@ -4352,20 +4352,25 @@ and should not be used.
 
 \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. An example of this is the
+  flag or the \field{used_event} field. 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{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}.
-- 
MST