Re: [PATCH RFC v4 00/16] qemu: towards virtio-1 host support

Cornelia Huck
2014-11-27T16:28:49Z

On Thu, 27 Nov 2014 18:18:25 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Thu, Nov 27, 2014 at 05:06:51PM +0100, Cornelia Huck wrote:

> > So we should have a per-device callback into the transport layer, say
> > check_legacy()?
>
> I would just have 2 masks: legacy_features and features.

But these belong to the device type and the transport just needs to
trigger usage of the right one, right?

>
> > For ccw, this would check for the negotiated revision; for mmio, it
> > could check a device property configured with the device; and for pci,
> > whatever the mechanism is there :)
> >
> > A transport not implementing this callback is simply considered
> > legacy-only.
>
> I dislike callbacks. Let's just give all info to core,
> and have it DTRT.
>
Have a is_legacy flag in the vdev that is initialized to 1, and
transports can unset it when the revision is negotiated or during init?