On Friday 13 July 2007, James Bottomley wrote:
>
> > IC.
> >
> > - flush_kernel_dcache_page() is a no-op on ppc64
> > (ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE is defined on parisc only).
> >
> > - For reference, drivers/scsi/ipr.c (another ppc64 driver) just uses a
> > plain
> > kmap/memcpy/kunmap sequence
> >
> > So what should I do?
>
> Ask someone who knows the architecture ... Anton, Paulus or Benh ... I'm
> fairly certain PPC is VIPT and will need some kind of alias
> resolution ... perhaps its associative enough not to let the aliases be
> a problem.
I'm pretty sure that no ppc64 machine needs alias resolution in the kernel,
although some are VIPT. Last time we discussed this, Segher explained it
to me, but I don't remember which way Cell does it. IIRC, it automatically
flushes cache lines that are accessed through aliases.
It's probably a good idea to have the flush_kernel_dcache_page() in there
anyway, if only to serve as an example for people that copy it into
architecture-independent drivers, same as what we do for the
k{,un}map_atomic() that is also not required on ppc64.
Arnd <><
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