dc* (Data Cache) instructions in mem*() and *_page() functions not used on 8xx

[Joakim Tjernlund]

> > Joakim Tjernlund wrote:
> >
> > > It seems that even the newest 8xx chips still has problems. I did not expect that.
> >
> > It may be the parts are working fine.  I long ago removed the code necessary
> > to detect the exception conditions when the cache instructions faulted, so
> > I wouldn't expect them to work properly.
>
> Aah, that would explain why __copy_tofrom_user doesn't work I guess. But the
> rest seems to be fine. Maybe there should be a new config option that
> would one could enable for modern 8xx CPUs? With a big warning sign of cource
> and default to off. Maybe even add the missing exception handler?
>
>    Jocke

Dan, could you add the missing code for 8xx to detect the exception conditions when
the cache instructions faulted? I would like to give it a try.

Maybe add a new CONFIG option to allow 8xx to use these optimizations when
explicitly enabled. Perhaps it's enough to let it depend on CONFIG_8xx_CPU6, that is,
if CONFIG_8xx_CPU6 is set do NOT enable dcbz et. all, otherwise enable them?

        Jocke


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