Re: [Qemu-devel] [libvirt] [PATCH 0/9] i386: query-cpu-model-expansion test script

[Daniel P. Berrange]

On Thu, Jan 19, 2017 at 06:21:22PM +0100, David Hildenbrand wrote:
> 
> >> Also think about "query-cpu-model-expansion model=host type=static",
> >> which will primarily be used by libvirt on s390x. There is no way to
> >> expand this into a static cpu model. Faking anything will just hide errors.
> > 
> > Yes, static expansion of host model must always return an error
> > if it's not possible to expand.
> > 
> >>
> >> If "host" can't be expanded, QEMU has to be treated like there is no CPU
> >> model support (as for older QEMU versions).
> > 
> > OK. I will propose a patch updating the query-cpu-model-expansion
> > documentation to be more explicit about it.
> 
> The only real alternative I see would be disabling the query-cpu-model-*
> interface completely if KVM support is not available.
> 
> This would however mean, that the same QEMU binary would have the
> interface when running under TCG, but not when running under KVM on an
> old KVM version.
> 
> That also doesn't really feel right, or what do you think?

Yeah that really isn't good.  query-cpu-model-* needs to work on TCG
and *not* have a dependancy on KVM in that case, since you can be
running TCG s390 on a x86_64 host, so the host CPU is totally irrelevant
for TCG

Regards,
Daniel
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