[libvirt] [RFC] Support for CPUID masking v2
'Jiri Denemark'
jdenemar at redhat.com
Mon Sep 14 06:53:13 UTC 2009
> > I'm not sure how to deal with named CPUs suggested by Dan. Either we need
> > to come up with global set of named CPUs and document what they mean or
> > let drivers specify their own named CPUs and advertise them through guest
> > capabilities:
> > <guest>
> > ...
> > <cpu model="NAME">
> > <feature>NAME</feature>
> > ...
> > </cpu>
> > </guest>
> [IH] you also need to support removing a feature from the base cpu model,
> if it is disabled by bios, like the nx flag).
Indeed, the above XML snippet describes capabilities, that is what features
are turned on by each model name.
...
> > And finally, CPU may be configured in domain XML configuration:
> >
> > <domain>
> > ...
> > <cpu model="NAME">
> > <topology>
> > <sockets>NUMBER_OF_SOCKETS</sockets>
> > <cores>CORES_PER_SOCKET</cores>
> > <threads>THREADS_PER_CORE</threads>
> > </topology>
> >
> > <feature name="NAME" mode="set|check" value="on|off"/>
> > </cpu>
> > </domain>
> >
> > Mode 'check' checks physical CPU for the feature and refuses the domain to
> > start if it doesn't match. VCPU feature is set to the same value. Mode
> > 'set' just sets the VCPU feature.
While here, when configuring a domain, you would use something like
<cpu model="whatever">
<feature name="sse6" mode="set" value="off"/>
</cpu>
to turn off 'sse6' feature which was turned on by selecting CPU model
'whatever'.
Jirka
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