Question about OS activation

[Matt Hogstrom]

Can someone provide me a pointer in the tree that outlines the various  
ways OS instances are intiialized?  I'm thinking of the low-level OS  
things like initial user IDs, network information, startup scripting,  
etc.  Specifically, I'm looking for how this is handled for multiple  
OSes.

I'll poke in the tree but if someone has a quick pointer that would be  
appreciated.

Thanks