To run, make sure you have qemu installed and run the Makefile. This has only been tested on a Linux system (I used an Ubuntu 20.04 VM on top of a Windows 10 host) but it should work on any system that can run qemu and make Makefiles.
This bootloader is nothing fancy, it is the simplest it could be and the only thing it does is write an X onto the screen after booting (see kernel.c)
This was done following a tutorial.