No harness for Linux Kernel target

I'm confused about this example. Currently, there is no explanation regarding the harness and thread model for fuzzing the Linux kernel. Additionally, while it's mentioned that I can fuzz my own Linux kernel after patching it, there are no guidelines about how to patch the Linux kernel source code.
Also, I would be grateful if you could explain what changes should be made to both the kernel running on my own device (currently using the Nyx version downloaded from the repository) and the kernel used by QEMU. I'm unclear about what different modifications need to be applied to these two kernels.