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

[Eduardo Habkost]

On Mon, Jan 20, 2014 at 05:27:18PM +0100, Andreas Färber wrote:
> Am 20.01.2014 15:36, schrieb Eduardo Habkost:
> > This enables x2apic on the following CPU models: Conroe, Penryn,
> > Nehalem, Westmere, Opteron_G[12345].
> > 
> > Normally we try to keep the CPU model definitions as close as the real
> > CPUs as possible, but x2apic can be emulated by KVM without host CPU
> > support for x2apic, and it improves performance by reducing APIC access
> > overhead. x2apic emulation is available on KVM since 2009 (Linux
> > 2.6.32-rc1), there's no reason for not enabling x2apic by default when
> > running KVM.
> > 
> > About testing: Conroe, Penryn, Nehalem, Westemere and Opteron_G[123]
> > have x2apic enabled on RHEL-6 since RHEL-6.0, so the presence of x2apic
> > on those CPU models got lots of testing in the last few years. I want to
> > eventually enable x2apic on all other CPU models as well, but it will
> > require some testing to ensure it won't confuse guests.
> > 
> > This shouldn't affect TCG at all because features not supported by TCG
> > are automatically and silently disabled by QEMU when initializing the
> > CPU.
> > 
> > Signed-off-by: Eduardo Habkost <address@hidden>
> > ---
> > v1 was sent in September 2013:
> >   Message-Id: <address@hidden>
> >   http://article.gmane.org/gmane.comp.emulators.qemu/234541
> > 
> > It got an Acked-by from Gleb but it was ignored by all maintainers.
> 
> Sorry, was still unread in my inbox. What changed between this version
> and said v1? Just moving to _1_7? I.e. should I add back Gleb's Acked-by
> before your Sob when applying?

Yes, the only change from v1 was on the compat code. I didn't think I
should have included Gleb's Acked-by because he didn't review the compat
code changes (and I could have made mistakes when rebasing), but if you
think it is appropriate, you can pull Gleb's Acked-by.

-- 
Eduardo