Intro to Low-Level Graphics on Linux
Personally I find the heavy use of ioctls in modern Linux APIs bit distasteful. Sure, its pragmatic and easy, but it really feels abusing the UNIX mantra of "everything is a file" when the only operation you can do for that "file" is some specific ioctls. I first noticed this in the very nice KVM article that ran on LWN few years back, and now again here. I really wish there was some more structured way of talking to the kernel, but I can understand that introducing a ton of new syscalls probably is not practical.