On Tue, Apr 29, 2014 at 10:11:08PM -0300, Marcelo Tosatti wrote: > On Tue, Apr 29, 2014 at 06:17:17PM -0300, Eduardo Habkost wrote: > > KVM never supported the MONITOR flag so it doesn't make sense to have it > > enabled by default when KVM is enabled. > > > > The rationale here is similar to the cases where it makes sense to have > > a feature enabled by default on all CPU models when on KVM mode (e.g. > > x2apic). In this case we are having a feature disabled by default for > > the same reasons. > > > > In this case we don't need machine-type compat code because it is > > currently impossible to run a KVM VM with the MONITOR flag set. > > > > Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> > > Why relying on the kernel filtering is not sufficient ?
Because: * When "enforce" is used, it will prevent a VM from being started because the feature is not supported by the kernel. * When "enforce" is not used, it breaks the guest ABI when the values returned by GET_SUPPORTED_CPUID change. -- Eduardo
