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ACPI_THERMAL(4)        FreeBSD Kernel Interfaces Manual        ACPI_THERMAL(4)

     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)
     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.

             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.
             Temperature to start critical suspend to disk (S4).
             Temperature to start critical shutdown (S5).
             Temperatures at which to switch to the corresponding active
             cooling level.  For instance, values of "3200 3100" mean to
             switch on _AC0 at 320.0K and _AC1 at 310.0K.  The lower the _ACx
             value, the higher the cooling power.

     All temperatures are represented in tenths of a Kelvin.  For example,
     300.0K is represented by the integer 3000.  To convert to units of
     Centigrade, the formula is (x - 2731.5) / 10.

     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.

FreeBSD 11.0-PRERELEASE        December 27, 2003       FreeBSD 11.0-PRERELEASE


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