Scott Wood scottwood@freescale.com wrote on 2011/01/18 18:27:49:
On Tue, 18 Jan 2011 01:18:34 +0100 Joakim Tjernlund joakim.tjernlund@transmode.se wrote:
How do you think a solution for all boards would look like? The only other method is can think of is some MMU trickery and I don't even see how you can make that work on all boards and
You don't need to make the MMU trick work on all boards, just your board (or cpu family), because it wouldn't be imposing anything on the rest of the system. Do we actually have someone who needs this feature on a board without a suitable MMU, large lockable cache or other SRAM, hardware bank switching, or other mechanism that can be confined to early low-level board/cpu-specific code?
Wolfgang seems to think so. As I read his reply he wants a solution for all boards which I don't think is possible. I do think my approach comes closest though. I did try BATs but I didn't get very far.
you would probably be locked to specific address ranges if you use BATs as defined on PowerPC
You'd have alignment constraints, but it's good enough for bank switching.
Alignment and a suitable bank size so you don't fall into your environment. That may make BATs hard to use in general.