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!
The videos below the break go into significant depth on writing and debugging an emulator not to mention the inner workings of DOOM, but fear not if it’s not your thing. Everything can be found in a GitHub repository, and there are straightforward instructions should you wish to try it yourself.