# Linux Kernel Module Cheat

### 38.13. Build variants

It often happens that you are comparing two versions of the build, a good and a bad one, and trying to figure out why the bad one is bad.

Our build variants system allows you to keep multiple built versions of all major components, so that you can easily switching between running one or the other.

- Linux kernel build variants

- QEMU build variants

- gem5 build variants

- Buildroot build variants