The Illustrated Guide to Linux First Patch

Step 1: Standards and practices

Everything you have to know for working on the Linux Kernel has been created by Linus Torvalds. That is the Linux Kernel itself and git.

Oh.. almost everything. Linus seemed content with the C programming language.

Linux kernel is currently under a mixture of code following C89/C90 and C99 standards. By taking a look into the Makefiles you’ll find the majority compiling with -std=gnu89, that is to say they are using the C89/C90 standard with some extensions.