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acpi_thermal - ACPI thermal management subsystem



      acpi_thermal - ACPI thermal management subsystem


      device acpi


      The acpi_thermal driver provides the thermal management features of the
      ACPI module.  This driver has a sysctl(8) interface and a devd(8) notifi‐
      cation 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 accord‐
      ing 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
              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 override).
              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.
              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.
              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 cool‐
              ing level.  The lower the _ACx value, the higher the cooling
      All temperatures are printed in Celsius.  Values can be set in Celsius
      (by providing a trailing "C") or Kelvin (by leaving off any trailing let‐
      ter).  When setting a value by sysctl(8), do not specify a trailing deci‐
      mal (i.e., 90C instead of 90.0C).


      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
                 0xcc    Non-standard notify that the system will shutdown if
                         the temperature stays above _CRT or _HOT for one more
                         poll cycle.
      acpi(4), cpufreq(4), acpidump(8)


      Michael Smith
      This manual page was written by Takanori Watanabe.


Based on BSD UNIX
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