[U-Boot] [PATCH 4/4] powerpc: Add LINK_OFF calls in early C-code.

[Joakim Tjernlund]

Scott Wood <scottwood at freescale.com> wrote on 2011/01/18 18:27:49:
> On Tue, 18 Jan 2011 01:18:34 +0100
> Joakim Tjernlund <joakim.tjernlund at 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.