Re: [virtio] [PATCH v2] transitional issues: add new IDs for all devices

[Rusty Russell <rusty@au1.ibm.com>]

"Michael S. Tsirkin" <mst@redhat.com> writes:
> On Fri, Sep 13, 2013 at 10:19:45AM +0930, Rusty Russell wrote:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> > +Non-transitional devices must use the larger of the IDs.
>> > +For example use Device ID=0x101 for a network card.
>> > +
>> > +Both transitional and non-transitional drivers must match all
>> > +IDs for a given device type.
>> 
>> The last one doesn't make sense.  Non-transitional drivers should only
>> care about 0x10x.  That would be achieved by not listing the smaller
>> numbers outside the Legacy Interface section.
>> 
>
> I thought so originally, but this won't work.
> Recall that transitional devices have IDs 0x1 0x2 etc.
>
> We definitely want transitional devices to support
> non-transitional drivers so non-transitional drivers  must support
> IDs 0x101 etc.
>
> In other words IDs should not be used to distinguish between
> legacy and non-legacy devices - we have a feature bit for that.
> They are only a means to distinguish between transitional
> and non-transitional devices.

OK, that needs to be spelled out clearly in the spec, since we both
thought the same thing.

The eventual spec is supposed to use RFC-2119-style MUST etc. language.
This would be a good place to start, IMHO.

Cheers,
Rusty.