Re: [virtio-dev] [PATCH] pci: use revision id 1 or higher for non transitional devices

On Tue, Nov 05, 2013 at 05:02:25PM +1030, Rusty Russell wrote:
> "Michael S. Tsirkin" <> writes:
> > VIRTIO-34
> >
> > Signed-off-by: Michael S. Tsirkin <>
> > ---
> >  virtio-v1.0-wd01-part1-specification.txt | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt
> > index 6ab4ff8..b3f7c9e 100644
> > --- a/virtio-v1.0-wd01-part1-specification.txt
> > +++ b/virtio-v1.0-wd01-part1-specification.txt
> > @@ -802,10 +802,18 @@ supported by the device. The Subsystem Vendor ID should reflect
> >  the PCI Vendor ID of the environment (it's currently only used
> >  for informational purposes by the guest).
> >  
> > +All Drivers must match devices with any Revision ID, this
> > +is to allow devices to be versioned without breaking drivers.
> > +
> >  2.3.1.1.1 Legacy Interfaces: A Note on PCI Device Discovery
> >  -------------------------
> > -Transitional devices must also have a Revision ID of 0 to match
> > -this specification.
> > +Transitional devices must have a Revision ID of 0 to match
> > +legacy drivers.
> > +
> > +Non-transitional devices must have a Revision ID of 1 or higher.
> > +
> > +Both transitional and non-transitional drivers must match
> > +any Revision ID value.
> 
> Hmm, so a non-transitional driver should match revision ID 0?  Sure,
> it'll fail gracefully when it doesn't find the capability, but it's a
> bit weird.

Drivers should just ignore revision.
If you put it like this it is not weird anymore, right?

> Cheers,
> Rusty.


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MST