What is kernel configuration?

Running PowerTOP on an Ubuntu 10.10 system, one of the suggestions are

Enable the CONFIG_PM_ADVANCED_DEBUG kernel configuration option. This option will allow PowerTOP to collect runtime power management statistics.

What is a kernel configuration option and how do I enable it?

Can I put it as a startup parameter somewhere, or would I have to compile a new kernel?

Solution 1:

Kernel configurations are compiled in. You can check to see if it's configured by running this:

grep CONFIG_PM_ADVANCED_DEBUG /boot/config-`uname -r`

On mine, I see:

oli@bert:~$ grep CONFIG_PM_ADVANCED_DEBUG /boot/config-`uname -r`
# CONFIG_PM_ADVANCED_DEBUG is not set

I compile my own kernels but my config is derived from Ubuntu's. It's worth checking to see if it's been added since I started compiling.

If you want to recompile the kernel to enable this flag, your best starting point is here: https://help.ubuntu.com/community/Kernel/Compile

It's a bit of effort. You need a few packages and on a fast computer it takes at least 20 minutes just to do the compile. Add in configuration time and that you have to do this every time a security update comes out... It might not be worth it.

Solution 2:

You will also need to recompile with CONFIG_PM_DEBUG; you need both options set.

This should be set in Maverick and above already.

The plan is to enable it in Oneiric onwards for all but the ARM and POWERPC builds https://wiki.ubuntu.com/KernelTeam/Specs/KernelOneiricConfigReview