Re: [Qemu-devel] [PATCH] target-i386: enable x2apic by default on more recent CPU models

[Eduardo Habkost]

On Tue, Jan 21, 2014 at 05:13:50PM +0100, Paolo Bonzini wrote:
> Il 21/01/2014 16:51, Andreas Färber ha scritto:
> >>> We already do that for other bits (e.g. XSAVE/OSXSAVE),
> >Please point me to the commit, a search for xsave did not come up with a
> >commit changing such a thing - either it did not go through my queue or
> >it slipped me through: Bugs are no excuse to produce more bugs.
> 
> I meant that "-cpu SandyBridge" with TCG produces a CPU that doesn't
> have XSAVE.
> 
> >>> and in fact it
> >>> is the same that we do for KVM: the KVM_GET_SUPPORTED_CPUID result is
> >>> used to trim the generic feature bits.
> >Our model definitions are the place to put stuff that real CPUs have.
> >Either the CPU has it or it doesn't. If it does, then this patch is
> >fully correct and it's TCG's job to mask things out. If we're adding
> >artificial flags to the generic model definitions just to make KVM
> >faster, then it is wrong - we have a choice of post_initialize and
> >realize hooks for that.
> 
> It would make TCG faster as well, and there would be no reason
> really to avoid the "artificial" x2apic on TCG, if TCG implemented
> x2apic at all.

So, the discussion seem to have stalled.

Andreas, are you still against the patch, after the arguments from Paolo
and me?

-- 
Eduardo