Want to observe how OS works at lower level but find source code of linux and its features bewildering. Get started with the ->
Lions' Commentary on Unix 6th Edition, with Source Code, San Jose, CA: Peer-to-Peer Communications, 1996.
For your reference, here is the source code and here is the commentary.
Here is an another resource for OS implementation text, instead more precisely for Minix3 unix-based operating system :
Operating Systems : Design and Implementation by A.S. Tanenbaum
