Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set

[Michael S. Tsirkin]

On Wed, Jul 22, 2015 at 10:31:45AM +0100, Daniel P. Berrange wrote:
> On Wed, Jul 22, 2015 at 01:59:51PM +0800, Jason Wang 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.
> 
> Why is SCSI passthrough support not available in virtio 1.0 ? This
> will cause a regression for any users of that as & when QEMU changes
> to use virtio 1.0 by default. Can we not fix this regression instead.
> 
> Regards,
> Daniel

If we wanted to, we might be able to fix this but not for 2.4: we'd have
to extend the spec and guest drivers, in some way TBD.

Paolo would be best placed to answer whether this feature is desirable
in the future, I think the argument made when the spec was written was that
the feature is not widely used, and virtio scsi is available as
a replacement for people who need it.


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