Since 3 years I keep under my bed a hardprinted copy of the Solaris dynamic linker source code, and another of the AIX kernel machine-dependent (esp. the boot phase).

the Solaris RealTime Dynamic Linker code is available at: http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/usr/sr...

and the AIX kernel is available on your favourite peer-to-peer network. This is my bible. Look at the files under aix/bos/kernel/ml/, you will learn a lot about kernel-land and Power(PC) architecture.

I enjoy it as a real piece of poetry, each function as an unique verse. You can even appreciate some erotic pieces (especially if you try to compare your reverse IDA analyse with the source).

If you are more openminded you can read the Linux kernel bootcode files (under linux/arch/$ARCH/kernel/). The first time is still the harder one, and you'll always remember it. But it worst it.