How to disable acpi thermal?

[Kevin Oberman]

> Date: Tue, 15 Jan 2008 15:34:41 -0500 (EST)
> From: Daniel Eischen <deischen at freebsd.org>
> Sender: owner-freebsd-acpi at freebsd.org
> 
> [ Redirected from -current ]
> 
> On Mon, 14 Jan 2008, Alexandre "Sunny" Kovalenko wrote:
> 
> >
> > On Mon, 2008-01-14 at 21:56 -0500, Daniel Eischen wrote:
> >>
> >> Thermal zone 0 skyrockets past 110C in a couple of minutes
> >> when trying to build a kernel.  All the other zones stay
> >> relatively static.  I suspect something is wrong somewhere
> >> because this machine is very lightly loaded and has never
> >> had a problem until now.  I just upgraded it from 4.x to
> >> 7.0.
> >
> > It need not to be bogus -- if I turn off fan on my ThinkPad it will
> > overheat and shut itself down within couple of minutes of buildworld,
> > starting from the relative cool state. From the look of the stuff below
> > your fan should kick in no later then 10 seconds after tz0 reached 77C.
> > Do you hear it running before shutdown? If yes, maybe lowering threshold
> > in AC0 down from 77C will help. If not -- you will need to figure out
> > who is supposed to turn on the fan. You can dump your ASL (instructions
> > in the handbook) and post it someplace accessible -- I will take a look
> > and maybe spot something interesting, but, being far from the expert in
> > the field, I do not promise too much.
> 
> I posted the acpidump here:
> 
>    http://people.freebsd.org/~deischen/stl2.iasl
> 
> The problem is that acpi_thermal keeps shutting down the system
> after 2 minutes into a buildkernel.  The system has no load other
> than the buildkernel at the time it shuts down.
> 
> 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.
> 
> Any ideas?

Bad CPU or bad support chip? The temperature on modern CPUs is measured
on the silicon. There is usually a junction that is simply brought out
to a pair of pins and an external device "reads" the temperature. 

It's possible that the chip has a bad junction or support chip that is
providing bogus information. On most processors it looks like the
thermal "crowbar" that will kill power if the temperature reaches about
135C or something near to that. (I have not looked at a spec sheet for
any CPUs in about three years, so things might have changed. That is
outside the control of acpi_thermal, so turning it off may remove alarms
and prevent a shutdown at _CRT, but that won't prevent a shutdown at the
higher "meltdown" temperature. That one is intended for loose/missing
hear sinks or other major thermal failures.

It is also possible that there is a BIOS bug that is reporting the
temperature incorrectly. That seems less likely as it would probably be
noticed by a lot of folks.

Is there any chance that the heat sink is loose or improperly attached?
(It happened to me a few years ago.)
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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