Messages in this thread |  | | Date | Wed, 18 Jun 2014 14:59:39 -0400 | | From | "Gabriel L. Somlo" <> | | Subject | Re: [PATCH 3/3] KVM: x86: correct mwait and monitor emulation |
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On Wed, Jun 18, 2014 at 11:30:07AM -0700, Eric Northup wrote: > Quoting Gabriel's post http://www.spinics.net/lists/kvm/msg103792.html : > > [...] > > > E.g., OS X 10.5 *does* check CPUID, and panics if it doesn't find it. > > It needs the MONITOR cpuid flag to be on, *and* the actual > > instructions to work.
That was an argument in favor of finding a mechanism to allow (qemu) users to enable an otherwise default-off monitor cpuid flag.
We definitely don't want to advertise monitor/mwait availability to guests which would otherwise sanely fail back to a hlt-based idle loop when cpuid tells them monitor/mwait are not available :)
However, check my earlier proposal of backing out of monitor/mwait entirely (as it turns out, there's a kernel command line to tell OS X not to use monitor/mwait, which is IMHO vastly preferable to creating "undocumented" KVM hacks :)
Thanks much, --Gabriel
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