Debugging an ioctl Problem on OpenBSD
I was trying to use a V4L2
Ruby module
on my OpenBSD laptop but ran into a problem where sending the V4L2 ioctl
s from
this module would fail, while other V4L2 programs on OpenBSD worked fine.
Since I got a few questions recently about kernel development and debugging, I thought I'd write up how I finally tracked it down and fixed it. (Spoiler: it was not an OpenBSD problem.)