Linux Kernel Module Cheat

https://stackoverflow.com/questions/29151235/how-to-de-optimize-the-linux-kernel-to-and-compile-it-with-o0

O=0 is an impossible dream, O=2 being the default.

So get ready for some weird jumps, and <value optimized out> fun. Why, Linux, why.

The -O level of some other userland content can be controlled as explained at: Optimization level of a build.