Re: Use of virtio device IDs

[Anthony Liguori <aliguori@us.ibm.com>]

Anthony Liguori wrote:
> Hi Rusty,
>
> I've written a PCI virtio transport and noticed something strange.  
> All current in-tree virtio devices register ID tables that match a 
> specific device ID, but any vendor ID.
>
> This is incompatible with using PCI vendor/device IDs for virtio 
> vendor/device IDs since vendors control what device IDs mean.  A 
> simple solution would be to assign a fixed vendor ID to all current 
> virtio devices.  This doesn't solve the problem completely though 
> since you would create a conflict between the PCI vendor ID space and 
> the virtio vendor ID space.
>
> The only solutions seem to be virtualizing the virtio vendor/device 
> IDs (which is what I'm currently doing) or to mandate that the virtio 
> vendor ID be within the PCI vendor ID space.  It's probably not 
> necessary to make the same requirement for device IDs though.

There's another ugly bit in the current implementation.

Right now, we would have to have every PCI vendor/device ID pair in the 
virtio PCI driver ID table for every virtio device.

This means every time a virtio device is added to Linux, the virtio PCI 
driver has to be modified (assuming that each virtio device uses a 
unique PCI vendor/device ID) :-/

Regards,

Anthony Liguori

> What are your thoughts?
>
> Regards,
>
> Anthony Liguori
>