linux-kernel - Re: [PATCH] i386: add command line option "local_apic_timer_c2

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Date:	29 Mar 2007 16:15:28 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Len Brown <lenb@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	william.morrow@....com, jordan.crouse@....com,
	Thomas Gleixner <tglx@...utronix.de>,
	Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Mingming Cao <cmm@...ibm.com>, Adrian Bunk <bunk@...sta.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	Mariusz Kozlowski <m.kozlowski@...land.pl>,
	Oliver Pinter <oliver.pntr@...il.com>,
	Sid Boyce <g3vbv@...eyonder.co.uk>,
	Nick Piggin <npiggin@...e.de>,
	Jens Axboe <jens.axboe@...cle.com>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH] i386: add command line option "local_apic_timer_c2_ok"

Len Brown <lenb@...nel.org> writes:

> On an Intel processor, it seems that the safe and simple route
> is if the system exports C2 or deeper, don't use the LAPIC timer.
> (which is what 2.6.21-rc5 is doing as of this moment)
> We may be able to white-list some systems over time.

On AMD it is the same, except that there seems to be at least
one system that does C2 like things while only exporting C1.
That is why i proposed to check for a battery too -- if there is one
always disable it too.

-Andi
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