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Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features
From: |
David Hildenbrand |
Subject: |
Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features |
Date: |
Wed, 22 Jun 2016 09:34:49 +0200 |
> > > > 2) Requiring a running QEMU instance to run
> > > > query-cpu-model-comparison
> > > >
> > > > With my previous query-host-cpu proposal, the task of comparing
> > > > the configuration requested by the user with host capabilities
> > > > can be done directly by libvirt. This way, no extra QEMU instance
> > > > needs to be run before starting a VM.
> > >
> > > I think we can just easily get around this by not comparing a guest CPU
> > > to host (except for the explicit virConnectCompareCPU, which is not very
> > > useful in its current form anyway).
> >
> > If there is some flexible way around that, great. But I think we (s390x)
> > could
> > life without this additional query.
>
> So if I understand correctly, you say you don't need the API to compare
> guest CPU to host CPU, right? If so, that's exactly what I said too.
>
I think the coffee didn't do its work already :) . I wanted to write that we can
_with_ this additional query. Meaning the involved overhead would be ok - in my
opinion for s390x.
What we could do to avoid one compare operation would be:
a) Expand the host model
b) Expand the target model (because on s390x we could have migration unsafe
model)
c) Work with the runnability information returned via query-cpu-definitions
But as we have to do b) either way on s390x, we can directly do a compare
operation. (which makes implementation a lot simpler, because libvirt then
doesn't have to deal with any feature/model names).
David
- [Qemu-devel] [RFC 22/28] s390x/kvm: let the CPU model control CMM(A), (continued)
- [Qemu-devel] [RFC 22/28] s390x/kvm: let the CPU model control CMM(A), David Hildenbrand, 2016/06/21
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Eduardo Habkost, 2016/06/21
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/21
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Eduardo Habkost, 2016/06/21
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/21
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Eduardo Habkost, 2016/06/21
- Re: [Qemu-devel] [libvirt] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/22
- Re: [Qemu-devel] [libvirt] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features,
David Hildenbrand <=
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/22
- Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/23
Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, Jiri Denemark, 2016/06/21
Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features, David Hildenbrand, 2016/06/30