ACPI thermal management subsystem
driver provides the thermal
management features of the ACPI module. This driver has a
interface and a
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.
driver also activates the
active cooling system according to each thermal zone's setpoints.
- Number of seconds to continue active cooling once started. A new active
cooling level will not be selected until this interval expires.
- Number of seconds between polling the current temperature.
- 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
- 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
- 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
- Current thermal zone status. These are bit-masked values.
- Current temperature for this zone.
- Temperature to start passive cooling by throttling down CPU, etc. This
value can be overridden by the user.
- Temperature to start critical suspend to disk (S4). This value can be
overridden by the user.
- Temperature to start critical shutdown (S5). This value can be overridden
by the user.
- 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)
not specify a trailing decimal (i.e., 90C instead of 90.0C).
Notifies are passed to userland via devd(8)
for examples. The
driver sends events with the
- The fully qualified thermal zone object path as in the ASL.
- An integer designating the event:
- Current temperature has changed.
- One or more trip points (_ACx, _PSV) have changed.
- One or more device lists (_ALx, _PSL, _TZD) have changed.
- Non-standard notify that the system will shutdown if the temperature
stays above _CRT or _HOT for one more poll cycle.
This manual page was written by Takanori