[libvirt] Fwd: [PATCH] qemu: Add cmd_per_lun, max_sectors to virtio-scsi

Daniel P. Berrange berrange at redhat.com
Thu Jul 3 08:40:40 UTC 2014

On Wed, Jul 02, 2014 at 06:48:36PM -0600, Eric Blake wrote:
> On 07/02/2014 06:28 PM, Nicholas A. Bellinger wrote:
> >> QEMU is not the only hypervisor that libvirt targets, so tieing libvirt
> >> names to QEMU names is a non-goal. We pick the names that make most sense
> >> in the context of libvirt.
> >>
> > 
> > Not sure I follow..  virtio-scsi is specific to QEMU/KVM, and per the
> > comment in the original patch:
> > 
> >   'Currently it only supports attribute <code>queues</code> (<span class="since">1.0.5</span>, QEMU and KVM only)'
> > 
> > would seem to indicate the parameter names are only used in the context
> > of QEMU/KVM, no..?
> Just because qemu is the only hypervisor driver that _currently_ uses
> the feature doesn't preclude the libxl hypervisor from _also_ gaining
> support for the feature in a future libvirt release, at which point the
> documentation would mention the new version number for the additional
> use of the feature.  Again, the name qemu chose is not necessarily the
> best name compared to what it might map to in libxl or any other
> hypervisor, so libvirt tries to pick names that are consistent with
> other libvirt terms, even if they don't match underlying qemu names.
> > 
> > If the virtio-scsi parameters are intended to be used across
> > hypervisors, then matching them to QEMU's own names doesn't really
> > matter.  But if they are specific to virtio-scsi and only used by
> > QEMU/KVM instances, then renaming them to something arbitrary to libvirt
> > is pointless and confusing.
> virtio is not necessarily a qemu-only concept.

Indeed, virtio is already used outside of QEMU & Linux by the FreeBSD
BHyve virt platform.

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