[Pkg-acpi-devel] Bug#444028: acpid: problems with ACPI critical trip points

[Michal Suchanek]

Followup-For: Bug #444028


Hello

the critical trip points in kernel are there because they exist in some
ACPI table.

So the critical temperature should not be arbitrary but read from the
hardware (although I am not sure if this is the case on ppc machines).

There might be a possiblity to change the temperature with a parameter
to the thermal module. Failing that you can patch the kernel.

The other problem with critical zones is that on some hardware the
kernel would occasianally read ridiculously high temperature. At least
this is what I think because the machine would run for days and then
suddenly shutdown while idle. I have patched my kernel so that it logs
the temperature every few seconds but I have not been able to reproduce
a trip with such kernel so far.

The shutdown script is not hardcoded in the kernel, you can set it with
sysctl just like modprobe.

The other thing that fails is actually lowering the temperature before
it reaches the trip point, and this is acpid's job.

There should be a policy for more cooling that runs more fans than the
bare minimum dictated by the acpi tables. On a notebook I tested there
were three fan objects (which probably represent different speeds of the
same fan), and only the lowest was ever started automatically. These
were connected to an actively cooled zone (as opposed to critical zone)
but running the higher fans cooled down the critical zone considerably.

Another thing acpid might do is slowing down the CPU. On ppc macs this
is perfectly normal way of avoiding overheating on OS X. That's probably
one of the reasons they are so slow. Unfortunately, slowing down the GPU
is usually not so easy.

Thanks

Michal

-- System Information:
Debian Release: 5.0
  APT prefers stable
  APT policy: (1001, 'stable'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.28.3 (SMP w/1 CPU core; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages acpid depends on:
ii  libc6                         2.7-18     GNU C Library: Shared libraries
ii  lsb-base                      3.2-20     Linux Standard Base 3.2 init scrip
ii  module-init-tools             3.4-1      tools for managing Linux kernel mo

acpid recommends no packages.

acpid suggests no packages.

-- debconf-show failed