Add support for overriding the values for _CRT, _HOT, and _PSV via sysctl.

Prevent casual modification by requiring hw.acpi.thermal.user_override to
be set first.  Fix printing of negative temperatures in the K->C conversion.
Document the remaining thermal sysctls.

MFC after:	3 days

1 files changed, 17 insertions, 9 deletions

diff --git a/share/man/man4/acpi_thermal.4 b/share/man/man4/acpi_thermal.4
index c557b8d..08992a1 100644
--- a/share/man/man4/acpi_thermal.4
+++ b/share/man/man4/acpi_thermal.4
@@ -55,6 +55,16 @@ 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.min_runtime
+Number of seconds to continue active cooling once started.
+A new active cooling level will not be selected until this interval expires.
+.It Va hw.acpi.thermal.polling_rate
+Number of seconds between polling the current temperature.
+.It Va 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).
 .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.
@@ -73,25 +83,23 @@ These are bit-masked values.
 Current temperature for this zone.
 .It Va hw.acpi.thermal.tz%d._PSV
 Temperature to start passive cooling by throttling down CPU, etc.
+This value can be overridden by the user.
 .It Va hw.acpi.thermal.tz%d._HOT
 Temperature to start critical suspend to disk (S4).
+This value can be overridden by the user.
 .It Va hw.acpi.thermal.tz%d._CRT
 Temperature to start critical shutdown (S5).
+This value can be overridden by the user.
 .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" .
+All temperatures are printed in Celsius.
+When setting a value by
+.Xr sysctl 8 ,
+do not specify a trailing decimal (i.e., 90 instead of 90.0C).
 .Sh NOTIFIES
 Notifies are passed to userland via
 .Xr devd 8 .