[Linux Kernel] How to study Linux Kernel?

I believe there are tremendous ways for doing that but I think the good way to start is the following.

1) use youtube kernel-related presentations

http://www.youtube.com/watch?v=L2SED6sewRw

In this video, Greg introduces how kernel is developing, who have contributed to kernel development, and how to involve contributing to kernel.

http://www.youtube.com/watch?v=JiIl123dz50&feature=relmfu

This video is google tech talk which looks a lot like an ad hoc discussion, very fun though.

http://www.youtube.com/watch?v=TjH2Ufc6t2E&feature=related

Kernel work-through from SVLUG (Silicon Valley Linux Users Group).

2) read books to see the overall picture of Linux kernel. I don't recommend you to go deep in the first place with books, just brief and overall understanding. (Understanding Linux Kernel, Linux Device Driver of Orelly; also recommending Essential Linux Device Drivers of Prentice Hall)

3) find a target (such as making a simple driver, adding a new system call, etc) and do that. For better using the APIs of kernels, I recommend you to look up documentations folder in the Linux kernel source code. There are pretty good stuffs.

4) ALWAYS TRY TO READ OPEN SOURCE CODE