RE: APM idle problems - how to check if BIOS halts CPU?

From: Andreas Steinmetz (
Date: Thu Dec 13 2001 - 15:38:15 EST

On 13-Dec-2001 Borsenkow Andrej wrote:
> Oh, my! I am ashamed. I totally missed the fact that default idle task
> alredy halts CPU. I must be getting old :(
> On Чтв, 2001-12-13 at 14:39, Andreas Steinmetz wrote:
>> I posted an apm patch and asked Marcelo to apply it. What you do see is
>> kapm-idled and the idle task both racing for idle time. There's even more
>> problems (search lkml for subject kapm-idled and have a look at the reply
>> from
>> Alan Cox on Dec 5 which does contain my original mail and the patch). With
>> the
>> patch e.g. the fan control of my laptop works properly which it never did
>> before.
> Unfortunately, this patch does not works as I'd expected. This patch
> does hide systime, but it does not cool CPU. With this patch system runs
> 4C hotter than it run when I replaced apm_do_idle() with apm_cpu_idle()
> in original apm.c

In this case you may try to disable idle calls when idle in the kernel
configuration. This defaults then to the idle task which does halt the
cpu and should be a nice workaround for a buggy bios.

> I'll try to get a closer look at weekend; any hints how to debug it are
> welcome.
> If you really do have a broken bios there's no other way than to
>> contact your system's vendor.
> Well, my vendor is ASUS and it is notorious for never answering bug
> reports from mere mortals. I also do not know how important Linux market
> is for them and Windows runs fine with ACPI (and Linux with ACPI does
> not have this problem as well. But I run Mandrake and they currently do
> not want to enable ACPI for different reasons). But I'll try anyway.
> Thank you
> -andrej

Andreas Steinmetz
D.O.M. Datenverarbeitung GmbH
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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:27 EST