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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.