[LinuxBIOS] raminit.c

I hope someone can clarify this for me. The main purpose of the  
raminit.c file is to:

a) setup the most minimal northbridge memory registry
b) detect spd to find memory parimeters
c) set the spd parimeters in the northbridge memory registry
d) startup memory

Is this correct??
The main question I have is how do I know which of the northbridge  
memory registers need to be setup on initially?? If they are to use  
their default values to I even need to include them?? Or should I just  
set them all up??
Please Help me out here.

Thanks - Joe