Novell LINUX ENTERPRISE DESKTOP 10 SP2 - DEPLOYMENT GUIDE 08-05-2008 Deployment Manual page 559

/proc/acpi/thermal_zone/
A separate subdirectory exists for every thermal zone. A thermal zone is an area
with similar thermal properties whose number and names are designated by the
hardware manufacturer. However, many of the possibilities offered by ACPI are
rarely implemented. Instead, the temperature control is handled conventionally by
the BIOS. The operating system is not given much opportunity to intervene, because
the life span of the hardware is at stake. Therefore, some of the files only have a
theoretical value.
/proc/acpi/thermal_zone/*/temperature
Current temperature of the thermal zone.
/proc/acpi/thermal_zone/*/state
The state indicates if everything is ok or if ACPI applies active or passive
cooling. In the case of ACPI-independent fan control, this state is always ok.
/proc/acpi/thermal_zone/*/cooling_mode
Select the cooling method controlled by ACPI. Choose from passive (less perfor-
mance, economical) or active cooling mode (full performance, fan noise).
/proc/acpi/thermal_zone/*/trip_points
Enables the determination of temperature limits for triggering specific actions, like
passive or active cooling, suspension (hot), or a shutdown (critical). The
possible actions are defined in the DSDT (device-dependent). The trip points deter-
mined in the ACPI specification are critical, hot, passive, active1, and
active2. Even if not all of them are implemented, they must always be entered
in this file in this order. For example, the entry echo 90:0:70:0:0 >
trip_points sets the temperature for critical to 90 and the temperature
for passive to 70 (all temperatures measured in degrees Celsius).
/proc/acpi/thermal_zone/*/polling_frequency
If the value in temperature is not updated automatically when the temperature
changes, toggle the polling mode here. The command echo X >
/proc/acpi/thermal_zone/*/polling_frequency causes the temper-
ature to be queried every X seconds. Set X=0 to disable polling.
None of these settings, information, and events need to be edited manually. This can
be done with the Powersave daemon (powersaved) and its various front-ends, like
powersave, kpowersave, and wmpowersave. See
(page 546).
Section 28.3.3, "ACPI Tools"
Power Management 543