# Linux Kernel Module Cheat
The perfect emulation setup to study and develop the <<linux-kernel>> v5.9.2, kernel modules, <<qemu-buildroot-setup,QEMU>>, <<gem5-buildroot-setup,gem5>> and x86_64, ARMv7 and ARMv8 <<userland-assembly,userland>> and <<baremetal-setup,baremetal>> assembly, <<c,ANSI C>>, <<cpp,C++>> and <<posix,POSIX>>. <<gdb>> and <<kgdb>> just work. Powered by <<about-the-qemu-buildroot-setup,Buildroot>> and <<about-the-baremetal-setup,crosstool-NG>>. Highly automated. Thoroughly documented. Automated <<test-this-repo,tests>>.

### 37.3. Out-of-order execution

https://en.wikipedia.org/wiki/Out-of-order_execution

gem5’s model is gem5 `DerivO3CPU`.

Allows working around data dependencies: you can execute the second next instruction forward if the first next depends on the current one.

Likely used on basically all (?) 2020 non-power-constrained CPUs.

As mentioned at: https://stackoverflow.com/questions/10074831/what-is-general-difference-between-superscalar-and-ooo-execution it is in theory possible for an out-of-order CPU to not a Superscalar processor, but the combination is so natural (since you can look ahead, you might as well run it!) that it is not super common.

- Speculative execution

- Re-order buffer

- Register renaming