FreeBSD and manual fan control on a Lenovo t410

Here is a quick way to manually control your fan speed on your Lenovo T410 running FreeBSD 10.x:

First load the kernel module:
$ kldload acpi_ibm.ko

Then check your new sysctl’s:

$ sysctl -a | grep -i fan
dev.acpi_ibm.0.fan_speed: 4527
dev.acpi_ibm.0.fan_level: 7 1

Turn on manual mode:
$ sysctl

Set fan for instance, to level 7:
$ dev.acpi_ibm.0.fan_level: 7

The man page for acpi_ibm.ko details the different levels:

	     Indicates at what speed the fan should run	when being in manual
	     mode.  Values are ranging from 0 (off) to 7 (max).	 The resulting
	     speed differs from	model to model.	 On a T41p this	is as follows:
	     0		 off
	     1,	2	 ~3000 RPM
	     3,	4, 5	 ~3600 RPM
	     6,	7	 ~4300 RPM

It appears that my max speed is 4527 RPM.
You can check your temperature using
$ sysctl -a|grep temperature

FYI, mine shows 93.0C (!) right now cause this business laptop is utterly s**t since they put the inlet for air next to the air outlet. Really Genious. At least it helps a little to lower the CPU frequency using powerd.


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