[libvirt] [RFC 0/6] Probe and expose GIC capabilities

Andrea Bolognani abologna at redhat.com
Tue Mar 22 14:39:49 UTC 2016


On Tue, 2016-03-22 at 08:57 -0400, Cole Robinson wrote:
> On 03/21/2016 01:28 PM, Andrea Bolognani wrote:
>> > This series implements support for asking QEMU what GIC versions can
> > be used for guests, eg:
>> >   <features>
> >     <gic version='2'/>
> >   </features>
>> > and exposing such information to users via domain capabilities.
>> > QEMU patches that implement the query-gic-capabilities QMP command:
>> >   https://lists.gnu.org/archive/html/qemu-devel/2016-03/msg04465.html
>> > Cheers.
>>> > Andrea Bolognani (6):
> >   conf: Get rid of virDomainCapsDevice
> >   qemu: Probe GIC capabilities
> >   schema: Validate GIC capabilities
> >   conf: Expose GIC capabilities
> >   qemu: Fill in GIC capabilities
> >   qemu: Cache GIC capabilities
>> Code looks good to me but I skimmed it. You labelled this an RFC... are you
> waiting for design comments from other people or should I do a full review?

Design comments are definitely good, it's my first time implementing
something like this so I want to be sure I got it right. If you feel
like doing a full review that would be lovely, but keep in mind that
the QEMU bits haven't landed yet, so merging right away would be out
of the question.

The idea was pretty much to get the code out there instead of sitting
on it forever, so that interested parties could take it for a spin
with a patched QEMU and spot design / implementation issues early.

I still need to add at least a couple of test cases, but that needs
further digging. Any ideas about how to generate new files for
tests/qemucapabilitiesdata? :)

To answer your other question - the thread starts at [1], and it's
a long one. The take away is that, once this information is exposed,
management applications can let the user decide whether they want
to give the guest a GIC v2 or v3, and warn if they try to run a v3
guest on a host that only supports v2.

Cheers.


[1] https://www.redhat.com/archives/libvir-list/2015-December/msg00502.html
-- 
Andrea Bolognani
Software Engineer - Virtualization Team




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