Re: [Qemu-devel] [PATCH 0/4] virtio: Move host features to backends

[Peter Maydell]

On 20 April 2015 at 09:54, Cornelia Huck <address@hidden> wrote:
> The reason why blk is ok is that it adds the feature bits in its
> ->get_features() callback. net expects the feature bits already present
> and removes not supported ones and therefore requires
> statically-defined bits somewhere.
>
> If we move the feature bits to virtio-net and virtio-scsi, it should
> work for virtio-mmio - but the feature bit propagation from the device
> into the transport becomes a bit useless.
>
> Could net and scsi add the feature bits dynamically in their
> ->get_features() callback instead? This should work for virtio-mmio as
> well afaics.

I think this is what Shannon's v2 patchset just posted does -- could
you check that it doesn't break s390 by accident?

> In the end, we should probably end up with the same mechanism for all
> device types.

Definitely agreed. I suspect we just missed the net and scsi devices
because getting this wrong doesn't make virtio-mmio totally unusable...

thanks
-- PMM