freebsd/share/man/man4/acpi_thermal.4

.\" Copyright (c) 2003 Takanori Watanabe.
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.Dd December 27, 2003
.Dt ACPI_THERMAL 4
.Os
.Sh NAME
.Nm acpi_thermal
.Nd ACPI thermal management subsystem
.Sh SYNOPSIS
.Cd "device acpi"
.Sh DESCRIPTION
The
.Nm
driver provides the thermal management features of the ACPI module.
This driver has a
.Xr sysctl 8
interface and a
.Xr devd 8
notification interface.
The sysctls export properties of each ACPI thermal zone object.
.Pp
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.
.Pp
The
.Nm
driver also activates the active cooling system according to
each thermal zone's setpoints.
.Sh SYSCTL VARIABLES
.Bl -tag -width indent
.It Va 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.
.It Va hw.acpi.thermal.tz%d.passive_cooling
If set to 1, passive cooling is enabled.
It does cooling without fans using
.Xr cpufreq 4
as the mechanism for controlling CPU speed.
Default is enabled for tz0 where it is available.
.It Va hw.acpi.thermal.tz%d.thermal_flags
Current thermal zone status.
These are bit-masked values.
.It Va hw.acpi.thermal.tz%d.temperature
Current temperature for this zone.
.It Va hw.acpi.thermal.tz%d._PSV
Temperature to start passive cooling by throttling down CPU, etc.
.It Va hw.acpi.thermal.tz%d._HOT
Temperature to start critical suspend to disk (S4).
.It Va hw.acpi.thermal.tz%d._CRT
Temperature to start critical shutdown (S5).
.It Va hw.acpi.thermal.tz%d._ACx
Temperatures at which to switch to the corresponding active cooling
level.
For instance, values of
.Qq Li "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.
.El
.Pp
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
.Li "(x - 2731.5) / 10" .
.Sh NOTIFIES
Notifies are passed to userland via
.Xr devd 8 .
See
.Pa /etc/devd.conf
and
.Xr devd.conf 5
for examples.
The
.Nm
driver sends events with the following attributes:
.Pp
.Bl -tag -width "subsystem" -compact
.It system
.Li ACPI
.It subsystem
.Li Thermal
.It type
The fully qualified thermal zone object path as in the ASL.
.It notify
An integer designating the event:
.Pp
.Bl -tag -width indent -compact
.It Li 0x80
Current temperature has changed.
.It Li 0x81
One or more trip points (_ACx, _PSV) have changed.
.It Li 0x82
One or more device lists (_ALx, _PSL, _TZD) have changed.
.It Li 0xcc
Non-standard notify that the system will shutdown if the temperature
stays above _CRT or _HOT for one more poll cycle.
.El
.El
.Sh SEE ALSO
.Xr acpi 4 ,
.Xr cpufreq 4 ,
.Xr acpidump 8
.Sh AUTHORS
.An -nosplit
.An Michael Smith
.Pp
This manual page was written by
.An Takanori Watanabe .