Re: [PATCH] i386: add command line option "local_apic_timer_c2_ok"

Andi Kleen
2007-03-29T15:51:44Z

"Langsdorf, Mark" <mark.langsdorf@amd.com> writes:

> > > If we really care about using the LAPIC timer on systems with deeper
> > > than C1 support, the only alternative seems to be to test
> > > if it actually works or not at boot and run-time.
> > > Otherwise, we wait for future hardware with guaranteed
> > > not to break under any (BIOS) conditions ships, and check for that.
> > >
> > > Based on what I read of the HP nx6325 where the LAPIC timer
> > > is breaking C1, AMD is in the same boat.
> >
> > The nx6325 (Turion 64 X2) exports only C1.
> > I'm not sure how the conclusion was drawn that it has
> > a broken lapic timer as reflected in the "nolapic_timer" patch:
>
> If both cores goes into C1 at the same time, the chipset
> can move the processor into a C3 like state called C1e.

... and that seems to break the local APIC timer.

> AMD can craft a patch to sort this out as soon as we have
> an idea what the framework is going to look like.

Just a snippet to detect it would be great. Then the dmi scan
could be removed and replaced with that. This would be a 2.6.21
candidate imho over the DMI hack.

-Andi