On 07/22/2015 04:58 PM, Cornelia Huck wrote: > On Wed, 22 Jul 2015 13:59:51 +0800 > Jason Wang <jasow...@redhat.com> wrote: > >> SCSI passthrough was no longer supported in virtio 1.0, so this patch >> fail the get_features() when both 1.0 and scsi is set. And also only >> advertise VIRTIO_BLK_F_SCSI for legacy virtio-blk device. >> >> Signed-off-by: Jason Wang <jasow...@redhat.com> >> --- >> hw/block/virtio-blk.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c >> index 4c27974..4716c3e 100644 >> --- a/hw/block/virtio-blk.c >> +++ b/hw/block/virtio-blk.c >> @@ -731,7 +731,14 @@ 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_add_feature(&features, VIRTIO_BLK_F_SCSI); >> + if (__virtio_has_feature(features, VIRTIO_F_VERSION_1)) { >> + if (s->conf.scsi) { >> + error_setg(errp, "Virtio 1.0 does not support scsi >> passthrough!"); >> + return 0; >> + } >> + } else { >> + virtio_add_feature(&features, VIRTIO_BLK_F_SCSI); >> + } >> >> if (s->conf.config_wce) { >> virtio_add_feature(&features, VIRTIO_BLK_F_CONFIG_WCE); > Do we advertise F_SCSI even if scsi is not configured in order to keep > the same bits as before? I'm afraid I don't remember, that thread was > long :/ > > I'm asking because I'd like to depend on that bit to decide whether I > can negotiate revision 1 for ccw and subsequently offer VERSION_1. It > would be an easy thing to do, and I'd like to avoid mucking around with > device-specific configuration from the transport.
I don't see much difference. Both of our patches needs to set scsi to off to have 1.0 device. And I don't see advantages that did it from transport. If it has, we probably need something similar in virtio-pci. > > To illustrate what I'm talking about, my current patchset for virtio-1 > on ccw is here: > > git://github.com/cohuck/qemu virtio-1-ccw-2.5 > Looks like patch "virtio-blk: scsi is legacy only" breaks backward compatibility because VIRTIO_BLK_F_SCSI was not notified when scsi is off. Thanks