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From: Lee Revell <rlrevell@joe-job.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Pavel Machek <pavel@ucw.cz>, M <mru@mru.ath.cx>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: High pitched noise from laptop: processor.c in linux 2.6
Date: Sat, 16 Oct 2004 23:33:23 -0400	[thread overview]
Message-ID: <1097984002.2148.44.camel@krustophenia.net> (raw)
In-Reply-To: <1097979705.13269.9.camel@localhost.localdomain>

On Sat, 2004-10-16 at 22:21, Alan Cox wrote:
> On Sul, 2004-10-17 at 02:24, Lee Revell wrote:
> > > And heavily reduced accuracy on a lot of laptops where 1000Hz
> > > is enough to make the clock slide every time the battery state is
> > > queried or an SMM event triggers.
> > Wouldn't such a laptop be horribly broken?  1ms is a LONG time to
> > disable interrupts.  That's millions of CPU cycles...
> 
> Yes, and most laptops have this problem. They use SMM traps to talk to
> the battery including huge delay loops and during those SMM traps no
> interrupt code runs.
> 

Ugh!  I was under the impression that mostly older machines had this
problem and it was a minority of laptops.  I could not find a lot of 
info on SMM  - several of the links I found were DDJ "Undocumented
Corner" articles.

Anyway this explains probably half the weird bug reports on the linux
audio user list.

Lee


  reply	other threads:[~2004-10-17  3:44 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-07  9:30 Fraz
2004-10-07 10:32 ` Pavel Machek
2004-10-07 10:53   ` Måns Rullgård
2004-10-07 14:32     ` Pavel Machek
2004-10-16 19:52       ` Lee Revell
2004-10-16 21:46         ` Alan Cox
2004-10-17  1:24           ` Lee Revell
2004-10-17  1:50             ` Kyle Moffett
2004-10-17  2:21             ` Alan Cox
2004-10-17  3:33               ` Lee Revell [this message]
2004-10-22 11:40               ` Alexandre Oliva
2004-10-16 19:59       ` Måns Rullgård
2004-10-16 20:42         ` Pavel Machek
2004-10-07 14:34     ` Pavel Machek
2004-10-17  0:45   ` Alex Riesen
2004-10-07 10:37 ` Christian Hesse
2004-10-17  5:21 Albert Cahalan
2004-10-18  3:51 Yu, Luming
2004-10-18 11:41 ` Pavel Machek
2004-10-20 14:47   ` Måns Rullgård
2004-10-20 15:47     ` Pavel Machek
2004-10-20 16:37       ` Måns Rullgård
2004-10-20 16:49         ` Jan-Benedict Glaw
2004-10-20 16:53           ` Pavel Machek
2004-10-20 16:53         ` Lee Revell
2004-10-20 17:13           ` Måns Rullgård
2004-10-21 20:32             ` Lee Revell
2004-10-21 21:39               ` Jon Masters
2004-10-20 23:31   ` Giuseppe Bilotta

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