How to disable acpi thermal?

[Nate Lawson]

Peter Jeremy wrote:
> On Tue, Jan 15, 2008 at 03:34:41PM -0500, Daniel Eischen wrote:
>> The system is a Intel STL2 Tupelo motherboard with 1 CPU, the
>> other CPU socket being occupied by a CPU terminator thingy.
>> I uncovered the rackmount system and watched it while building
>> a kernel.  With the cover off the acpi monitored temperature
>> went to 107C and stayed there.  It only took a minute or two
>> to get there.  I felt around inside the chassis and nothing
>> was even near being to warm or hot.  With the cover on, the
>> temperature goes to 111/112C before being shutdown by acpi_thermal
>> (the limit being 110C).  There is no way anything in that
>> chassis is anywhere near 100C.  I've disabled acpi_thermal
>> for now, but it'd be nice to get a better fix.
> 
> This implies that the reported temperature does have some association
> with reality.  What does the BIOS report?  One possibility is that
> one of the motherboard support chips has died.
> 
> If your CPU supports it, you could try using coretemp(4).
> 
> Getting back to your original question, my laptop used to suffer from
> occasional spikes to 146°C in one zone (not CPU).  My work-around was
> to add the following to /etc/sysctl.conf:
> # Increase tz2 allowable temperature so the occasional spikes to 146°C won't
> # trigger a shutdown.  Note that the temperature is specified in deci-kelvins
> hw.acpi.thermal.user_override=1
> hw.acpi.thermal.tz2._CRT=4231
> 
> I'd keep a close eye in it in case the reported temperature really is
> accurate.

Laptops are different.  The BIOS authors often use the embedded
controller (which only laptops have) to access the SMBUS.  So when the
EC timed out trying to access it, you'd get some wild reading
temporarily.  I think I fixed most EC issues in my rewrite that's in 7.0
so you should try there again.

You can now specify values in Celsius or Fahrenheit by appending a "C"
or "F", see the acpi_thermal man page.

-- 
Nate