Re: [Qemu-devel] [PATCH 2/2] virtio-net: mark VIRTIO_NET_F_GSO as legacy

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Michael S. Tsirkin (mst@redhat.com) wrote:
> virtio 1.0 spec says this is a legacy feature bit,
> hide it from guests in legacy mode.
> 
> Note: for cross-version migration compatibility,
> we keep the bit set in host_features.
> The result will be that a guest migrating cross-version
> will see host features change under it.
> As guests only seem to read it once, this should
> not be an issue. Meanwhile, will work to fix guests to
> ignore this bit in virtio1 mode, too.

OK, but if they're actually using the feature they'll carry
on working ?

Dave

> Cc: qemu-stable@nongnu.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/net/virtio-net.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 20aa63e..b68c69d 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1942,6 +1942,7 @@ static void virtio_net_class_init(ObjectClass *klass, void *data)
>      vdc->guest_notifier_pending = virtio_net_guest_notifier_pending;
>      vdc->load = virtio_net_load_device;
>      vdc->save = virtio_net_save_device;
> +    vdc->legacy_features |= (0x1 << VIRTIO_NET_F_GSO);
>  }
>  
>  static const TypeInfo virtio_net_info = {
> -- 
> MST
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK