On 20.12.2009, at 18:18, Michael S. Tsirkin wrote: > On Sun, Dec 20, 2009 at 06:17:02PM +0100, Alexander Graf wrote: >> >> On 20.12.2009, at 17:56, Michael S. Tsirkin wrote: >> >>> On Sun, Dec 20, 2009 at 05:59:33PM +0200, Avi Kivity wrote: >>>> On 12/20/2009 05:51 PM, Michael S. Tsirkin wrote: >>>>> >>>>>> Maybe we should make -cpu host the default. That will give the best >>>>>> performance for casual users, more testing for newer features, and will >>>>>> force management apps to treat migration much more seriously. The >>>>>> downside is that casual users upgrading their machines might experience >>>>>> issues with Windows. Feature compatibility is not just about migration. >>>>>> >>>>> This seems very aggressive. Can't we whitelist features that we know >>>>> about? Further, doesn't KVM already do this? >>>>> >>>>> >>>> >>>> It does, but without -cpuid host you're stuck with qemu64 (kvm.ko >>>> doesn't add features userspace didn't request). >>> >>> Hmm, then, shouldn't either kvm or qemu mask features that we do not >>> emulate well enough to make windows not crash? >> >> -cpu host does that already, no? >> >> Alex > > I expected so, but Avi here seems to say windows will crash if you > use a new CPU with it ...
Avi, have you narrowed it down to a specific feature bit? Alex
