Re: [PATCH] x86-64: Disable local APIC timer use on AMD systemswith C1E

From: Ingo Molnar
Date: Wed Sep 26 2007 - 04:32:07 EST

* Rafael J. Wysocki <rjw@xxxxxxx> wrote:

> On Tuesday, 25 September 2007 22:55, Thomas Gleixner wrote:
> > On Tue, 2007-09-25 at 22:55 +0200, Rafael J. Wysocki wrote:
> > > I have reworked the patch a bit so that it applies on top of 2.6.23-rc8-mm1
> > > and compiles (my version is attached).
> > >
> > > With this patch applied, the kernel boots correctly on the nx6325.
> >
> > I know. It's basically enforced "noapictimer".
> >
> > But this still does not explain why your nasty box booted current
> > mainline with "apicmaintimer" on the kernel command line.
> Now it doesn't do that any more.
> As I wrote in the other thread, I think that _sometimes_ the CPU
> doesn't enter the C1E state (or how it's called) and then the box
> boots and works.

Can you see any correlation between being on AC or on battery and this
bug occuring? Sometimes the BIOS might even do C states depending on
whether the box was booted up on AC or on battery. (and sometimes the
kernel calibrates things differently when booting up on battery [lower
speed] - so this can have an effect too.)

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