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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.

SEE ALSO

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

AUTHORS

     Michael Smith

     This manual page was written by Takanori Watanabe.