Ubuntu Manpage: acpi_thermal — ACPI thermal management subsystem

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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.min_runtime
Number of seconds to continue active cooling once started. A new active cooling level will not
be selected until this interval expires.

hw.acpi.thermal.polling_rate
Number of seconds between polling the current temperature.

hw.acpi.thermal.user_override
If set to 1, allow user override of various setpoints (below). The original values for these
settings are obtained from the BIOS and system overheating and possible damage could occur if
changed. Default is 0 (no override).

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.passive_cooling
If set to 1, passive cooling is enabled. It does cooling without fans using cpufreq(4) as the
mechanism for controlling 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. This value can be overridden
by the user.

hw.acpi.thermal.tz%d._HOT
Temperature to start critical suspend to disk (S4). This value can be overridden by the user.

hw.acpi.thermal.tz%d._CRT
Temperature to start critical shutdown (S5). This value can be overridden by the user.

hw.acpi.thermal.tz%d._ACx
Temperatures at which to switch to the corresponding active cooling level. The lower the _ACx
value, the higher the cooling power.

All temperatures are printed in Celsius. Values can be set in Celsius (by providing a trailing "C") or
Kelvin (by leaving off any trailing letter). When setting a value by sysctl(8), do not specify a
trailing decimal (i.e., 90C instead of 90.0C).

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