Re: [Qemu-devel] [PATCH V4 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set

[Michael S. Tsirkin]

On Mon, Jul 27, 2015 at 12:28:23PM +0200, Paolo Bonzini wrote:
> 
> 
> On 27/07/2015 11:49, Jason Wang wrote:
> > +    if (__virtio_has_feature(features, VIRTIO_F_VERSION_1)) {
> 
> No double underscores in userspace code.  Longstanding so it can be
> fixed after 2.4 is out---but please remember to do it.
> 
> > +        if (s->conf.scsi) {
> > +            error_setg(errp, "Virtio 1.0 does not support scsi 
> > passthrough!");
> 
> Unclear error message, as one would expect SCSI passthrough not to work
> anyway for e.g. a disk backed by a file.

Right - so I suggested:
        Virtio modern does not support scsi passthrough - please set 
disable-modern=on or switch to virtio-scsi.
With that change - ACK?

> 
> It's not a big deal as long as you will disable VIRTIO_BLK_F_SCSI by
> default in the same release that enables VIRTIO_F_VERSION_1 by default.
> 
> Paolo
> > +            return 0;
> > +        }
> > +        virtio_add_feature(&features, VIRTIO_F_ANY_LAYOUT);
> > +    } else {
> > +        virtio_add_feature(&features, VIRTIO_BLK_F_SCSI);
> > +    }