> Joakim Tjernlund wrote:
>
> > I don't follow you here, do you need to do all this for a modern(>=D4) 8xx
> > CPU?
>
> Yes. On "working" silicon, the dcbz (among others) requires special
> processing.....probably enough to ensure it costs more to use this
> instruction in a general purpose case.
hmm, then I asume that a "working" 8xx is different from any other PPC that
uses the dcbz? All other PPC arches are allowed to use the dcbz instruction.
>
> > I hope not, but something needs to be done since copytofrom_user does not
> > work for me.
>
> What do you mean it doesn't work? It should work fine if you don't
> try to use the dcbz. That is, leave the code alone. The bigger problem
> is the newer glibc library has to be modified to conditionally not use
> this as well.
I mean that if I remove the #ifndef CONFIG_8xx restrictions in
__copy_fromto_user(),
linux does not work anymore(init hangs). That was the experiment I did earlier
in this thread.
clear_page() and copy_page() work fine if I remove #ifndef CONFIG_8xx.
I removed the #ifndef CONFIG_8xx in cacheble_memcpy() and cacheble_memzero()
also but
these seems to unused.
>
> > The same resoning goes for the new option. If you have a new enough(>=D4)
> > CPU,
> > then you can enable this optimization(I think?!).
>
> I don't know. Linux is the only OS that will cause VM faults on a dcbz,
> maybe it will never work. Until someone verifies it works on the newer
> silicon we can't assume it will. This certainly isn't a reason to not use
> the processor or not ship products.......
Right, I quite like the 860 and even more the 862P(100MHz) I just got :-)
Regards
Jocke
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