acpi_thermal(4)

NAME

acpi_thermal – ACPI thermal management subsystem

SYNOPSIS

device acpi

DESCRIPTION

The acpi_thermal driver provides the thermal management features of the ACPI module. This driver has a sysctl(8) interface and a devd(8) notification interface. The sysctls export properties of each ACPI thermal zone object.

There can be multiple thermal zones in a system. For example, each CPU and the enclosure could all be separate thermal zones, each with its own setpoints and cooling devices. Thermal zones are numbered sequentially in the order they appear in the AML.

The acpi_thermal driver also activates the active cooling system according to each thermal zone's setpoints.

SYSCTL VARIABLES

hw.acpi.thermal.tz%d.active: Current active cooling system state. If this is non-negative, the appropriate _AC%d object is running. Set this value to the desired active cooling level to force the corresponding fan object to the appropriate level.
hw.acpi.thermal.tz%d.thermal_flags: Current thermal zone status. These are bit-masked values.
hw.acpi.thermal.tz%d.temperature: Current temperature for this zone.
hw.acpi.thermal.tz%d._PSV: Temperature to start passive cooling by throttling down CPU, etc.
hw.acpi.thermal.tz%d._HOT: Temperature to start critical suspend to disk (S4).
hw.acpi.thermal.tz%d._CRT: Temperature to start critical shutdown (S5).
hw.acpi.thermal.tz%d._ACx: Temperatures at which to switch to the corresponding active cooling level. For instance, values of "3200 3100" mean to switch on _AC0 at 320.0K and _AC1 at 310.0K. The lower the _ACx value, the higher the cooling power.

All temperatures are represented in tenths of a Kelvin. For example, 300.0K is represented by the integer 3000. To convert to units of Centigrade, the formula is (x - 2731.5) / 10.

NOTIFIES

Notifies are passed to userland via devd(8). See /etc/devd.conf and devd.conf(5) for examples. The acpi_thermal driver sends events with the following attributes:

system

ACPI

subsystem

Thermal

type

The fully qualified thermal zone object path as in the ASL.

notify

An integer designating the event:

0x80: Current temperature has changed.
0x81: One or more trip points (_ACx, _PSV) have changed.
0x82: One or more device lists (_ALx, _PSL, _TZD) have changed.
0xcc: Non-standard notify that the system will shutdown if the temperature stays above _CRT or _HOT for one more poll cycle.

AUTHORS

Michael Smith

This manual page was written by Takanori Watanabe.