Look Ma, No MMU!
You can add this to the list of things done with Linux because someone figured they could pull it off, as there isn’t much of a usage case for a MMU-less system in real life. On the other hand being able to run programs, like DOOM for instance, without a hardware memory manager is rather impressive. cnlohr built an emulator that does exactly that!
The emulated hardware is a RISC-V system running the Linux 5.18.0 kernel and the best part is that there are a full set of instructions on GitHub so you can try it out too! If you are interested in just how minimalistic and tiny a working computer can be it is worth checking it out. The graphics might not be awe inspiring but running Doom on a RISC-V rv32ima is very impressive!