As part of our "community" program at Collabora, I've had the chance to attend to a workshop on kernel hacking at UrLab (the ULB hackerspace). I never touched any part of the kernel and always saw it as a scary thing for hardcore hackers wearing huge beards, so this was a great opportunity to demystify the beast.
We learned about how to create and build modules, interact with userspace using the /sys pseudo-filesystem and some simple tasks with the kernel internal library (memory management, linked lists, etc). The second part was about the old school /dev system and how to implement a character device.
I also discovered lxr.free-electrons.com which is a great tool for browsing and find your way through a huge code base. It's definitely the kind of tool I'd consider re-using for other projects.
So a very a cool experience, I'm still not seeing myself submitting kernel patches any time soon but may consider trying to implement a simple driver or something if I ever need to. Thanks a lot to UrLab for hosting the event, to Collabora for letting me attend and of course to Hastake who did a great job explaining all this and providing fun exercises (I had to reboot only 3 times! But yeah, next time I'll use a VM :) )
Club Mate, kernel hacking and bulgur