virtio — archive

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

From: Rusty Russell <[email protected]>
To: [email protected]
Date: Thu, 06 Mar 2014 00:44:00 -0000

"Michael S. Tsirkin" <[email protected]> writes: > On Tue, Feb 25, 2014 at 01:07:40PM +1030, Rusty Russell wrote: >> > +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. > > 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. OK, but I don't know how much it will help in practice. If a driver is supporting legacy it might as well handle the !ANY_LAYOUT case. Cheers, Rusty.