virtio — archive

[PATCH 00/14] VIRTIO-71: conformance clauses for legacy interface

From: Michael S. Tsirkin <[email protected]>
To: [email protected]
Date: Wed, 05 Mar 2014 07:07:00 -0000

On Tue, Feb 25, 2014 at 01:07:40PM +1030, Rusty Russell wrote: > "Michael S. Tsirkin" <[email protected]> writes: > > --- > > 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} > > Move the example into a \note{} so it's clearly separated from > the normative section. Actually, move the normative requirements into > their own section, so this has to be split. > > > +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}. > > s/traditional/transitional/ > > s/if offered by the device traditional drivers MUST negotiate/ > transitional drivers MUST accept/ ? > > This requirement seems like a SHOULD, not a MUST to me though. > > Cheers, > Rusty. I made it a MUST because it creates a way for device to detect that driver is new and might use arbitrary layout. I'm worried that since everything seems to work without it, people will ignore the SHOULD requirement. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected]