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Software CPU cooling - apm / acpi

I would like to cool my CPU in the same way CPUIdle does it under
windows : using the Hlt instruction when the CPU is idle. As far as I
know, it's possible to achieve this under linux with apm or acpi, but I
have never succeded.

I am running a Debian unstable, kernel 2.4.19-k7 (binary package) with
an Athlon XP 1700+ on a MSI K7T266 Pro2.
I first tried with apm, loading the module with the following options:
apm power_off=1 idle_threshold=90
This seems to work fine for the poweroff function, but that's all. I was
expecting to see a process "kapm_idle" running, but it never happened.
And looking at the sources of apm, I came across this:

 *   1.16: Fix idle calling. (Andreas Steinmetz <ast@domdv.de> et al.)
 *         Notify listeners of standby or suspend events before notifying
 *         drivers. Return EBUSY to ioctl() if suspend is rejected.
 *         Daemonize now gets rid of our controlling terminal (sfr).
 *         CONFIG_APM_CPU_IDLE now just affects the default value of
 *         idle_threshold (sfr).
 *         Change name of kernel apm daemon (as it no longer idles) (sfr).

So it seems that apm no longer idles: how can I do it then?

I also tried with acpi. Here, I have no clues of how to make idle calls
to the processor. The acpi modules can be found in
 From what I have read, ospm_processor.o seems to be the one I need, but
if I simply load it, nothing happens... I didn't find any documentation
about these modules (and I don't know what parameters they can take).

Thank you very much if you can help with this problem!

My CPU is more than 20°C over the motherboard's temperature when I run
linux (that is 60°C, sometimes 65°), while it's only 3/4°C under windows
and a software cooler (dropping to 35/40°C)! And I can't afford to
change my CPU Cooler just now...

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