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Subject: Re: [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so
	far
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>, Adrian Bunk <bunk@stusta.de>,
       Arjan van de Ven <arjan@infradead.org>, Len Brown <lenb@kernel.org>
In-Reply-To: <200703161230.03712.maximlevitsky@gmail.com>
References: <200703161230.03712.maximlevitsky@gmail.com>
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Date: Sat, 17 Mar 2007 00:44:46 +0100
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Maxim,

On Fri, 2007-03-16 at 12:30 +0200, Maxim Levitsky wrote:
> 3) Sometimes I get this (once in three boots or so)
> 
> [   36.217405] ENABLING IO-APIC IRQs
> [   36.217587] ..TIMER: vector=0x31 apic1=0 pin1=2 apic2=-1 pin2=-1
> [   36.433917] APIC timer disabled due to verification failure.
> 
> And NO_HZ is disabled due to that (I get 1000/s timer's interrupts)
> I haven't investigated that yet.
> It looks like another new test that my hardware fails to perform... 

Yes, this is probably caused by SMM code trying to emulate a PS/2
keyboard from a (maybe connected or not) USB keyboard. Unfortunately we
have no way to disable this BIOS misfeature in the early boot process. 
Arjan, Len ?????

I built in this test to rule out bogus LAPIC timer calibration values
which are sometimes off by factor 2-10.

But I also built in a calibration against the PM-Timer, which turned out
to be quite reliable and I think the additional verification step is
only necessary for sytems without PM-Timer.

That was a bit over cautious from my side. I send a patch to avoid this
when PM-Timer is available in a separate mail.

	tglx