On Tue, Nov 05, 2002 at 05:13:48PM +0100, Kevin D. Kissell wrote: > > - 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? Because the source of memcpy_fromio and the destination of memcpy_toio are some I/O address, typically something like a shared memory region on a network card, which is accessed uncached. The uncached address region might be mapped in KSEG2/KSEG3 or accessed through an uncached region of XKPHYS or KSEG1 where as I recall your statment the effect of prefetch instructions is undefined. Ralf
