I've been writing a little port of the SeL4 OS kernel to rust, mostly as a learning exercise. I ran into a weird bug yesterday where some of my code wasn't running - qemu was just exiting. And I couldn't figure out why.

I asked codex to take a look. It took a couple minutes, but it managed to track the issue down using a bunch of tricks I've never seen before. I was blown away. In particular, it reran qemu with different flags to get more information about a CPU fault I couldn't see. Then got a hex code of the instruction pointer at the time of the fault, and used some tools I didn't know about to map that pointer to the lines of code which were causing the problem. Then took a read of that part of the code and guessed (correctly) what the issue was. I guess I haven't worked with operating systems much, so I haven't seen any of those tricks before. But, holy cow!

Its tempting to just accept the help and move on, but today I want to go through what it did in detail, including all the tools it used, so I can learn to do the same thing myself next time.