Getting into Linux Kernel Development

jeremy · 07-15-2015, 04:36 PM

Quote:

I don't know about you, but I've always found the idea of operating system kernels to be some mysterious and esoteric programming skill. Its importance cannot be overstated of course, but I've always felt that kernel programming and regular programming were two very separate skills.

I've recently had some patches merged into the Linux kernel, and thought it might be interesting to describe what I learnt from this brief dip into kernel development and how someone who is new to it might go about getting into this space.

A Bit of Backstory

Over the past year or so, I've been fascinated in reading kernel code. It all went over my head, of course, but I thought it was interesting seeing how the syscalls we used every day were implemented. I'd been pining for a good enough excuse to dip my toe into this weird and wonderful world of which I knew nothing about.

As luck would have it, I stumbled upon a feature request in libcontainer (now part of runC, and so the bug report has been deleted), and thought to myself "well, it's now or never". The bug report stated that "it would be nice if we could limit the number of PIDs in a cgroup", and I thought it would be a fairly easy project to do. "I'm quite a dab hand at C, how hard could it be?". The bug report linked to an old patchset (circa 2011) which would obviously need quite a bit of work to be brought up to date with the current state of the kernel. It turned out that it needed a complete rewrite, because of how much the internal APIs had changed in that time (and the fact that some of the hooks it depended on were removed because they were incredibly racy).

So, with all that in mind, I was ready to start writing a new version of the same patchset.

Advice for Getting Started

The easiest way to get started (from what I've heard) is to find a driver that doesn't work properly or look for some easy-looking bug report. I wouldn't recommend going about getting into the Linux kernel the way I did, I was thrown quite quickly into the deep end with no documentation in sight.

It's also a good idea to find someone on IRC (##kernel on freenode), or just email maintainers to ask them about what the problem you want to solve is (or even ask them if they have any bugs that you might be able to fix) and how to go about solving it. Maintainers are people too, so don't spam them if they don't reply within 15 minutes of your first email.

More at cyphar...

--jeremy

gnpaddy · 08-04-2015, 04:43 PM

Wow Thanks for the information..