Lm sensors

lm_sensors is an utility to monitor temperature, fan and voltage sensors.

Hardware detection
You can check the Supported Device List. Alternatively you can enable all drivers and let the sensors-detect program do the work for you.

Kernel
You need I2C support. Also you need to activate the following kernel options:

Software
Portage knows the global USE flag lm_sensors for enabling support for lm_sensors in other packages. Enabling this USE flag will pull in automatically:

The USE flags of lm_sensors are:

After setting this you want to update your system so the changes take effect:

Configuration
If you build all kernel options into the kernel, you can skip the next section and proceed with testing. Else configure your modules.

Configure modules
You need to run sensors-detect to detect your sensors and the needed kernel modules:

Follow the instructions and answer the last question, whether /etc/conf.d/lm_sensors should be generated/overwritten, with "yes".

You can now start lm_sensors:

To start lm_sensors at boot time, add it your default runlevel:

Testing
Now you can test, if everything works, e.g.:

Troubleshooting
See the lm_sensors FAQ.