Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
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) 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 ex-

	     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 ob-
	     ject 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.

FreeBSD	13.0			March 17, 2007			  FreeBSD 13.0


Want to link to this manual page? Use this URL:

home | help