Re: [PATCH RFC] virtio-pci: new config layout: using memory BAR

[Rusty Russell <rusty@rustcorp.com.au>]

Anthony Liguori <aliguori@us.ibm.com> writes:
> Hi Rusty,
>
> Rusty Russell <rusty@rustcorp.com.au> writes:
>
>> Anthony Liguori <aliguori@us.ibm.com> writes:
>>> 4) Do virtio-pcie, make it PCI-e friendly (drop the IO BAR completely), give
>>>    it a new device/vendor ID.   Continue to use virtio-pci for existing
>>>    devices potentially adding virtio-{net,blk,...}-pcie variants for
>>>    people that care to use them.
>>
>> Now you have a different compatibility problem; how do you know the
>> guest supports the new virtio-pcie net?
>
> We don't care.
>
> We would still use virtio-pci for existing devices.  Only new devices
> would use virtio-pcie.

My concern is that new features make the virtio-pcie driver so desirable
that libvirt is pressured to use it ASAP.  Have we just punted the
problem upstream?

(Of course, feature bits were supposed to avoid such a transition issue,
but mistakes accumulate).

Cheers,
Rusty.