From: "Ralf Baechle" <firstname.lastname@example.org>
> So I think the fix will have to be:
> - Avoid prefetching beyond the end of the copy area in memcpy and memmove.
> - Introduce a second variant of memcpy that never does prefetching. This
> one will be safe to use in KSEG1 / uncached XKPHYS also and will be used
> for memcpy_fromio, memcpy_toio and friends.
Assuming we had a version that prefetched exactly to the end
of the source memory block and no further, why would we need
the second variant?