Re: [Qemu-devel] [PATCH V4 3/3] virtio-blk: only clear VIRTIO_F_ANY_LAYOUT for legacy device

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 27, 2015 at 12:30:19PM +0200, Paolo Bonzini wrote:
> 
> 
> On 27/07/2015 11:49, Jason Wang wrote:
> > So this patch only clear VIRTIO_F_LAYOUT for legacy device.
> > 
> > Cc: Stefan Hajnoczi <stefanha@redhat.com>
> > Cc: Kevin Wolf <kwolf@redhat.com>
> > Cc: qemu-block@nongnu.org
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > ---
> >  hw/block/virtio-blk.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> > index 9acbc3a..1d3f26c 100644
> > --- a/hw/block/virtio-blk.c
> > +++ b/hw/block/virtio-blk.c
> > @@ -731,7 +731,6 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
> >      virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY);
> >      virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY);
> >      virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE);
> > -    virtio_clear_feature(&features, VIRTIO_F_ANY_LAYOUT);
> >      if (__virtio_has_feature(features, VIRTIO_F_VERSION_1)) {
> >          if (s->conf.scsi) {
> >              error_setg(errp, "Virtio 1.0 does not support scsi passthrough!");
> > @@ -739,6 +738,7 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
> >          }
> >          virtio_add_feature(&features, VIRTIO_F_ANY_LAYOUT);
> >      } else {
> > +        virtio_clear_feature(&features, VIRTIO_F_ANY_LAYOUT);
> >          virtio_add_feature(&features, VIRTIO_BLK_F_SCSI);
> >      }
> 
> This patch is unnecessary, since the feature is added back below under
> "if (__virtio_has_feature(features, VIRTIO_F_VERSION_1))".
> 
> Paolo

It's needed so we can apply
    virtio: set any_layout in virtio core