I am porting the northbridge 82845e for my motherboard. While coding raminit.inc file, I took the file from the 82830 chipset directory and modified as per the requirement of the 82845e chipset. Now I want to know, How to get the register value of the regsiters, like DRB DRAM ROW BOUNDARY REGISTER and etc. Do I need to read these regsiter value from the system using normal BIOS? I could not find much details about the values in the specification. Is my assumption is correct?
At least on the 430tx, the DRB is programmed with the highest amount of memory in each row, in 4MB chunks.
In my particular case, I have one single 64M dual-sided SODIMM in Row 0. So my DRB0 has a value of 0x10 (16*4 = 64) and DRB1-5 have the same value since they are not adding any memory.
Realistically you should be using a memory detection algorithm to try and find out how much memory is at each row and then programming the DRB registers correctly. I have never done this, though.