[U-Boot-Users] What are IBAT and DBAT?

[Shawn]

Hi,

When trying to port u-boot to a MPC8245 card, I'm not sure what IBAT and
DBAT register work for. For example, sl8245.h defines 4 regions of IBAT:
SDRAM_BASE, 0x40000000, 0x80000000, and 0xf0000000. 

1. Why are these regions defined? 

2. Does it mean that you cannot access that memory area if the area
hasn't been set by configuring IBAT and DBAT accordingly?

3. Can IBAT and DBAT be modified dynamically? For example, if I want to
access 0x70000000 ~ 0x78000000 temporarily, which is not defined in
configuration header file, can I change the configuration of one of IBAT
and DBAT pair, e.g. ibat2 and dbat2?

Thanks,
-Shawn.


		
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