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Re: [Qemu-devel] [PATCH] i386/cpu: name new CPUID bits
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH] i386/cpu: name new CPUID bits |
Date: |
Thu, 18 Oct 2012 22:14:23 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Oct 19, 2012 at 01:34:19AM +0200, Andre Przywara wrote:
> On 10/18/12 18:33, Eduardo Habkost wrote:
> >On Wed, Oct 17, 2012 at 11:17:26PM +0200, Andre Przywara wrote:
> >>Update QEMU's knowledge of CPUID bit names. This allows to
> >>enable/disable those new features on QEMU's command line when
> >>using KVM and prepares future feature enablement in QEMU.
> ...
> >>@@ -79,10 +79,10 @@ static const char *ext3_feature_name[] = {
> >> "lahf_lm" /* AMD LahfSahf */, "cmp_legacy", "svm", "extapic" /* AMD
> >> ExtApicSpace */,
> >> "cr8legacy" /* AMD AltMovCr8 */, "abm", "sse4a", "misalignsse",
> >> "3dnowprefetch", "osvw", "ibs", "xop",
> >>- "skinit", "wdt", NULL, NULL,
> >>- "fma4", NULL, "cvt16", "nodeid_msr",
> >>- NULL, NULL, NULL, NULL,
> >>- NULL, NULL, NULL, NULL,
> >>+ "skinit", "wdt", NULL, "lwp",
> >>+ "fma4", "tce", NULL, "nodeid_msr",
> >
> >You removed cvt16, here.
>
> On purpose, cvt16 is dead. It seems to have been advertised in the
> documentation for some time, but later disappeared. The respective
> instructions are now reported via the F16C flag in the Intel leaf.
>
> If you want to know more, I can dig deeper and ask some people. But
> the bit is now "reserved" and was never '1' in any silicon. (And was
> introduced by me into QEMU :-(
KVM doesn't report it on GET_SUPPORTED_CPUID, either, so it's impossible
to have any VM running with that bit set, even if was set on some
silicon.
It would be interesting to document that on the commit message, though.
>
> >
> >All the rest of the flags look OK to me.
>
> Thanks.
>
> Regards,
> Andre.
>
>
--
Eduardo