On Tue, Mar 29, 2016 at 06:58:03PM +0200, Cornelia Huck wrote: > On Tue, 29 Mar 2016 17:12:55 +0100 > Stefan Hajnoczi <stefa...@redhat.com> wrote: > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > index 2b5b248..1565e53 100644 > > --- a/include/hw/virtio/virtio.h > > +++ b/include/hw/virtio/virtio.h > > @@ -87,6 +87,7 @@ struct VirtIODevice > > VirtQueue *vq; > > uint16_t device_id; > > bool vm_running; > > + bool broken; /* device in invalid state, needs reset */ > > I'm wondering whether there's a sane way to track the broken state via > the NEEDS_RESET status bit instead. We'd probably want to filter out > this bit and not expose it to legacy drivers; but as the status field > is migrated anyway, we might be able to avoid a subsection for > migration.
If we set the non-VIRTIO 1.0 bit and migrate to an old QEMU that doesn't filter the bit then the guest will see it. Therefore I'm in favor of keeping vdev->broken separate from the status bit. The subsection only needs to be sent when the bit is set. Only migration of a broken device to an old QEMU will fail. All other cases continue to work so the subsection doesn't impose much incompatibility. Stefan
signature.asc
Description: PGP signature
