linux-kernel - Re: [PATCH] x86-64: Disable local APIC timer use on AMD systems with C1E

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Message-ID: <20070926083107.GB10713@elte.hu>
Date:	Wed, 26 Sep 2007 10:31:07 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>,
	Linus Torvalds <torvalds@...l.org>, Andi Kleen <ak@...e.de>,
	Chuck Ebbert <cebbert@...hat.com>,
	Dave Jones <davej@...hat.com>, Len Brown <lenb@...nel.org>,
	"Langsdorf, Mark" <mark.langsdorf@....com>
Subject: Re: [PATCH] x86-64: Disable local APIC timer use on AMD systems
	with C1E


* Rafael J. Wysocki <rjw@...k.pl> 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.)

	Ingo
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