Linux Kernel Cheatsheet

This page collects undocumented functions and ready-made recipes that can be used while dealing with the linux kernel compilation or development.

Configuration recipes

KConfig secrets

KConfig, the menu-driven configuration tool used for the kernel and other projects like buildroot, has some secret / poorly documented feature.

Searching: Press “/” and insert the CONFIG_* string you want to look at. A list will appear. You can use the numbers to directly jump to the proper section.

Saving changed to defconfig

So you have configured your development kernel and you want to update the defconfig accordingly. You usually change the text file directly, sometimes it happens that you mistyped a string and the build doesn’t as expected.

Next time, simply use “make savedefconfig”.

$ make savedefconfig 
$ cp defconfig arch/arm/configs/your_board_defconfig