Re: [Qemu-devel] question regarding odd CPU feature assignement

[Dan Kenigsberg]

Thanks!

On Mon, Sep 10, 2007 at 10:55:55AM +0200, Filip Navara wrote:
> It's not a typo. The short story is that there are two CPUID feature
> registers - 1/EDX and 0x80000001/EDX - that differ slightly. The later one
> was first used by AMD CPUs and mostly enhanced by adding new features to
> processors from the said company (3DNow and such). The first one was
> introduced by Intel and on AMD processor it's only used for compatibility,
> but not for AMD-specific extensions. You can learn more by looking at the
> tables on http://www.sandpile.org/ia32/cpuid.htm.
> 
> Best regards,
> Filip Navara
> 
> On 9/10/07, Dan Kenigsberg <address@hidden> wrote:
> >
> > Line 132 of qemu/target-i386/helper2.c has
> >
> >         /* currently not enabled for std i386 because not fully tested */
> >         env->cpuid_ext2_features = (env->cpuid_features & 0x0183F3FF);
> >
> > Which smells like a typo: I see no reason to make cpuid_ext2_features a
> > masked version of cpuid_features.
> >
> > Would someone care to elaborate?
> >
> > Thanks,
> >
> >     Dan.
> >
> >
> >