acpi_thermal(4)

NAME

acpi_thermal - ACPI thermal management subsystem

SYNOPSIS

device acpi

DESCRIPTION

The acpi_thermal driver provides the thermal management fea

tures 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 exam

ple, 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 corre

sponding fan
object to the appropriate level.

hw.acpi.thermal.tz%d.passive_cooling

If set to 1, passive cooling is enabled. It does

cooling without
fans using cpufreq(4) as the mechanism for control

ling CPU speed.
Default is enabled for tz0 where it is available.

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.

SEE ALSO

acpi(4), cpufreq(4), acpidump(8)

AUTHORS

Michael Smith

This manual page was written by Takanori Watanabe.

BSD December 27, 2003

BSD