[libvirt] [PATCH] cpuCompare: Fix comparison of two host CPUs

[Dan Kenigsberg]

Jiri,

I have an unrelated concern regarding the semantics of comparison of
host and guest CPUs.

I do not compare CPUs for fun, but rather to know if a guest can be run
on a specific host. However, this is not exactly what
virConnectCompareCPU gives me: A vmx-enabled host cpu is a superset of
itself, but it would not run itself as a guest since we do not have
nested vxm yet. Similarly, if we ever have svm-emulation-by-kvm, we
could be running svm guests on a vmx host.

Is it only me? Or should libvirt expose the more interesting meaning?

Dan.

On Mon, Jul 12, 2010 at 05:49:36PM +0200, Jiri Denemark wrote:
> When a CPU to be compared with host CPU describes a host CPU instead of
> a guest CPU, the result is incorrect. This is because instead of
> treating additional features in host CPU description as required, they
> were treated as if they were mentioned with all possible policies at the
> same time.