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From: Andrew Morton <akpm@linux-foundation.org>
To: tglx@linutronix.de
Cc: Maxim Levitsky <maximlevitsky@gmail.com>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Adrian Bunk <bunk@stusta.de>,
	Arjan van de Ven <arjan@infradead.org>,
	Len Brown <lenb@kernel.org>
Subject: Re: [PATCH] i386: trust the PM-Timer calibration of the local APIC timer
Date: Sun, 18 Mar 2007 00:12:35 -0800	[thread overview]
Message-ID: <20070318001235.f388f551.akpm@linux-foundation.org> (raw)
In-Reply-To: <1174089896.13341.362.camel@localhost.localdomain>

On Sat, 17 Mar 2007 01:04:56 +0100 Thomas Gleixner <tglx@linutronix.de> wrote:

> When PM-Timer is available for local APIC timer calibration we can skip
> the verification of the calibrated time value. The resulting error is
> quite small on a bunch of evaluated platforms and is less harming than
> the observed false positives.
> 
> We need to keep the verification on systems, which have no PM-Timer to
> avoid bogus local APIC timer calibrations in the range of factor 2-10,
> which can be observed when swicthing off the PM-timer support in the
> kernel configuration.
> 
> The wrong calibration values are probably caused by SMM code trying to
> emulate a PS/2 keyboard from a (maybe connected or not) USB keyboard.
> This prohibits the accurate delivery of PIT interrupts, which are used
> to calibrate the local APIC timer. Unfortunately we have no way to
> disable this BIOS misfeature in the early boot process.
> 
> Add also the dropped cpu_relax() back to the wait loops.

Is this a for-2.6.21 thing?

  parent reply	other threads:[~2007-03-18  8:17 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-16 10:30 [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so far Maxim Levitsky
2007-03-16 23:19 ` Len Brown
2007-03-17 23:00   ` Maxim
2007-03-17 23:32     ` Thomas Gleixner
2007-12-30  7:50       ` Mike Galbraith
2007-12-30 14:53         ` Ingo Molnar
2007-03-20 11:54     ` sysfs ugly timer interface (was Re: [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so far) Pavel Machek
2007-03-22 15:28       ` Greg KH
2007-03-22 15:41         ` Thomas Gleixner
2007-03-23  1:24         ` sysfs q [was: sysfs ugly timer interface] Jan Engelhardt
2007-03-23  4:48           ` Greg KH
2007-03-23  6:05             ` Jan Engelhardt
2007-03-16 23:39 ` [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so far Thomas Gleixner
2007-03-17 23:01   ` Maxim
2007-03-16 23:44 ` Thomas Gleixner
2007-03-17  0:04   ` [PATCH] i386: trust the PM-Timer calibration of the local APIC timer Thomas Gleixner
2007-03-17  7:22     ` Ingo Molnar
2007-03-17 13:24     ` Andi Kleen
2007-03-18  8:12     ` Andrew Morton [this message]
2007-03-18  8:45       ` Thomas Gleixner
2007-03-17  1:32   ` [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so far Len Brown
2007-03-17  9:56     ` Thomas Gleixner
2007-03-17 11:05       ` Thomas Gleixner
2007-03-17 16:52       ` Thomas Gleixner
2007-03-17 10:32     ` Arjan van de Ven
2007-03-17 13:26       ` Andi Kleen
2007-03-20  4:27         ` Greg KH
2007-03-20  6:30           ` Thomas Gleixner
2007-03-20  9:14           ` Arjan van de Ven
2007-03-20 11:36           ` Andi Kleen
2007-03-20 11:41             ` Oliver Neukum
2007-03-17 22:45     ` Maxim
2007-03-20  5:04   ` Lee Revell
2007-03-20  5:36     ` Eric St-Laurent
2007-03-20  9:15       ` Arjan van de Ven
2007-03-20 18:04         ` Andy Lutomirski
2007-03-20 22:58         ` Eric St-Laurent

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