I'm a C programmer, so I can with some effort gradually work my way through random Linux kernel things. But what I can do now instead is take a random function, ask GPT4 what it does and what subsystem it belongs to, and then ask GPT4 to write me a dummy C program that exercises that subsystem (I've taken to asking it to rewrite kernel code in Python, just because it's more concise and easy to read).
I don't worry at all about GPT4 hallucinating stuff (I'm sure it's doing that all the time!), because I'm just using its output as Cliff's Notes for the actual kernel code; GPT4 isn't the "source of truth" in this situation.