[U-Boot] MMU/PPC question

[Scott Wood]

On Tue, Mar 17, 2009 at 01:44:43PM -0700, SortaSBS Guy wrote:
> 1. Does u-boot/linux make any assumptions about how particular BAT
> registers are used? For example, we're not using PCI, and I was going
> to use those BAT registers to cover some memory-mapped peripheral I/O
> space (ex: icecube.c, DBAT3 and 4 are used for PCI, so I would use them
> instead for our I/O ranges.)

No, it's up to the individual board config.

> 2. Do you need a separate BAT register for each memory mapped I/O
> space? We have 4 chip selects, but could I arrange the chip selects to
> use a contiguous range and presumably cover that with a single BAT
> register?

Yes, if they all have the same mapping attributes.  Make sure you set the
guarded bit if there are any holes.

> 3. Would I need separate BAT registers for 8-bit vs. 16-bit devices?

No.

-Scott