On Mon, 2007-05-28 at 11:05 +0100, Russell King wrote: > On Sun, May 27, 2007 at 07:00:31PM -0500, James Bottomley wrote: > > Ok, output on parisc is: > > > > [EMAIL PROTECTED]:~$ ./a.out > > firstfirstfirst > > firstfirstfirst > > secondsecondsec > > > > Which is correct. It remains correct even if I drop the msync(). > > With Lennert's new program, I get mostly: > > firstfirstfirst > firstfirstfirst > firstfirstfirst > > but occasionally: > > firstfirstfirst > firstfirstfirst > secondsecondsec > > However, if I open code the memcpy() in the MAPREAD to copy one word > at a time, then I reliably get the "secondsecondsec" line. But if I > convert the memcpy() in MAPWRITE in the same way, I'm back to mostly > getting the failure with the occasional success. Utterly confused. > > Unless someone's got a theory, I'm stumped.
I think you're not flushing correctly in munmap() ... but I'm not sure the linux API actually requires this. We *have* to do it this way on parisc. In VIPT architectures, once you've lost the mapping, there's no real way to flush the page (well, except by setting up another congruent mapping pointing to the same physical page) so we have to flush before it's torn down otherwise we'd be at the mercy of cache eviction for coherency. We do it in tlb_start_vma(). James - To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
