[U-Boot] [PATCH] mpc83xx: Make it boot again

[Joakim Tjernlund]

Scott Wood <scottwood at freescale.com> wrote on 2010/11/17 20:27:01:
>
> On Wed, 17 Nov 2010 20:15:01 +0100
> Joakim Tjernlund <joakim.tjernlund at transmode.se> wrote:
>
> > Scott Wood <scottwood at freescale.com> wrote on 2010/11/17 20:03:25:
> > > The "load, conditional branch, isync" sequence is documented in the
> > > architecture manual (1.7.1), "even if the effects of the 'dependency'
> > > are independent of the value loaded".
> >
> > So it doesn't matter what address you do twi on?
> > Still, it would make a little more sense if
> > it read twi 0,r3,0
>
> It's not an address, it's data that is being compared with zero.  And it
> has to be r4, since that's what you want to create the data dependency
> on.

aha, should have looked closer on twi.

>
> The architecture suggests a similar but slightly longer sequence (but
> I don't think the wording rules out using twi), which may make the
> intent clearer:
>
> lwz   r4, ...
> cmpw   r4, r4
> beq   1f
> 1: isync

I hope so because this is a lot of fuzz for something so
simple, especially as the space is already GUARDED and no cache.

 Jocke