understanding the kernel

[George Mihai IACOB]

Hello!

I am a not-so-experienced programmer and I started a personal project 
which requires a deep understanding of the OpenBSD kernel - no, I am not 
going to fork another BSD style operating system. I wonder if there is 
documentation describing the kernel, other that the comments in the 
source. For a start, I am reading Andrew Tanenbaum's "Modern Operating 
Systems", 2nd edition and trying to follow the code in the kernel 
source, starting with sys/kern/init_main.c
Is this a wrong approach? Do you have other suggestions? I know there's 
no easy way and I am not looking for one, all I want is a starting point.
Regards,
George