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Subject: Re: [virtio] [PATCH v2] transitional issues: add new IDs for all devices
On Fri, Sep 13, 2013 at 10:19:45AM +0930, Rusty Russell wrote: > "Michael S. Tsirkin" <mst@redhat.com> writes: > > non-transitional devices should have been able to simply update > > revision ID to make sure legacy drivers are not loaded. > > Unfortunately, mistakes were made: > > - we didn't stress that drivers must check revision ID, > > and of course there's no easy way for drivers to > > test this failure path, > > so older versions of Windows drivers ignored revision > > (latest vision matches revision correctly) > > - CCW lacks revision ID field > > > > Both facts mean a non-transitional device would need > > a separate mechanism to prevent legacy drivers from > > loading. > > We aren't running out of device IDs yet, so > > let's use up some to resolve this. > > > > I incremented all IDs by 0x100 intentionally - > > for the PCI bindings, this should help remind people they can't > > just stick the Subsystem ID into the low byte of the Device ID. > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > OK, the only real proble I have with this is that you should remove the > 0x1, 0x2 from the non-legacy section. > > > +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. > And anyway, we don't want the non-legacy implementers to have to read > the legacy section. > > Cheers, > Rusty. Exactly. So 0x1 is not a legacy ID, that is why it's not described in a legacy section. > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. Follow this link to all your TCs in OASIS at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
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