[libvirt] cpuset / numa and qemu in TCG mode

[Martin Kletzander]

On Tue, May 12, 2015 at 05:27:34PM +1000, Tony Breeds wrote:
>On Mon, May 11, 2015 at 01:14:58PM +0200, Martin Kletzander wrote:
>
>> Determining this by version might not be reliable, but more
>> importantly working around bug in underlying software is something
>> that shouldn't be done at all IMHO.  Let the maintainers backport
>> whatever needs to be done.
>
>I agree with you in an ideal world but there are times when we do need
>to add work arounds in $project_x to work around issues in $project_y.
>
>> >Ther nova side will be pretty easy regardless.
>> >
>> >I'd say the best solution would be to back port the 'fix' but that seems like a
>> >lot of effort given the number of distros and libvirt versions potentiall
>> >involved.
>> >
>>
>> If you want the fix to be distro-agnostic, there's nothing easier than
>> back-porting the fix into our upstream maintenance branches.  Those
>> should make the life of distro maintainers easy (although it looks
>> like not many distros use it).
>
>And this is part of the problem.  If I understand correctly Ubuntu cloud-archive
>is using libvirt 1.2.12 which is *NOT* a maintenance release so that leaves us
>with doing an additional backport to 1.2.12 and getting the cloud-archive team
>to take it[1]  or Adding a hack to nova.  And that's just Ubuntu It's hard to
>say for sure that some vendor isn't running libvirt 1.2.12 also.
>
>> Having said that I'm not sure which commit(s) are those that need to
>> be back-ported.  Having known your libvirt version, it shouldn't be
>> too hard looking for the differences and finding the right commit.
>> When back-porting request is made on the list, it is usually acted
>> upon.  If you can't find the exact commit, let me know and I'll do my
>> best to help.
>
>So a git bisect points at:
>---
>commit a103bb105c0c189c3973311ff1826972b5bc6ad6
>Author: Daniel P. Berrange <berrange at redhat.com>
>Date:   Tue Feb 10 15:59:57 2015 +0000
>
>    qemu: fix setting of VM CPU affinity with TCG
>---
>
>A small amount of reading implies to me that we'd be looking at backporting
>a103bb105c0c189c3973311ff1826972b5bc6ad6 to any maintenance branch that contains
>b07f3d821dfb11a118ee75ea275fd6ab737d9500.  Which I think is 1.2.13 only, but I
>could be wrong.
>

1.2.13 has the commit already in the release and 1.2.12-maint has it
as a first back-port right after release.  The problem is that there
was no maintenance release of 1.2.12 yet.  Maybe they would use
1.2.12.1 if it existed.

I Cc'd Guido as an upstream debian maintainer, maybe he'll have some
insights.  @Guido: would it help if we created a maintenance release
from the v1.2.12-maint branch?  Or is the only thing missing the fact
that the launchpad bug is not moved to libvirt?

>If you don't beat me to it I'll request that backport to 1.2.13 *and* ask the
>Ubuntu guys to take it as well.
>
>I have to admit I'm still in 2 minds on the nova side.  Adding a wart to the
>libvirt driver for this specific bug for distros/vendors that are using 1.2.12
>seems a bit gross but ....
>
>Daniel what do you think?
>
>Yours Tony.
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