[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 21:24:16:
> On Tue, 18 Jan 2011 21:06:34 +0100
> Wolfgang Denk <wd at denx.de> wrote:
>
> > Dear Joakim Tjernlund,
> >
> > In message <OF287114D8.013B6E51-ONC125781C.00667DCD-C125781C.00673260 at transmode.se> you wrote:
> > > 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.
>
> What problems did you run into?

It crashed and burned :) I never got to the details.

>
> >
> > If we are talking about _all_ boards we have to keep a wider view.
> > For example, on MPC8xx there are not BATs. Not to mention other
> > architectures.
>
> I don't see why MPC8xx's MMU couldn't be used for this, although it
> might be a tight fit if you want to get everything into the pinned TLB
> entries.

I think it is harder that that. You probably need a tlb miss handler.

>
> Should we be talking about all boards, if the only user of this so far
> is on hardware that can do it in a less-intrusive way?
>
> Another thing to keep in mind is that Joakim's approach also won't work
> on all boards -- you need hardware that is capable of selecting from
> different entry points, where the entry address itself changes rather
> than flash banks being flipped around.

No, you only need gcc support for msingle-pic-base and some extra RAM
to hold the GOT(about 8KB would do I think) while still in flash.
Ah, you mean how to select which image to select? That is a small
piece of SW that checks both images and chooses the valid one and jumps
there.

 Jocke