SORRY - one more message to apologise for the multiple reposts (and automatically appended legal disclaimer). I've been moved to Exchange 2007 and trying to use Evolution + Exchange-MAPI. It looks like it went terribly wrong. Catalin On Wed, 2010-02-17 at 15:40 +0000, Catalin Marinas wrote: > On Wed, 2010-02-17 at 20:05 +1100, Benjamin Herrenschmidt wrote: > > On Tue, 2010-02-16 at 09:22 +0100, Oliver Neukum wrote: > > > This seems wrong to me. Buffers for control transfers may be > > > transfered > > > by DMA, so the caches must be flushed on architectures whose caches > > > are not coherent with respect to DMA. > > >=20 > > > Would you care to elaborate on the exact nature of the bug you are > > > fixing? > >=20 > > I missed part of this thread, so forgive me if I'm a bit off here, but > > if the problem is indeed I$/D$ cache coherency vs. PIO transfers, then > > this is a long solved issue on other archs such as ppc (and I _think_ > > sparc). > > The thread I started was indeed regarding I/D cache coherency and PIO. > But it diverged into DMA issues a few days ago (should have been a new > thread). > > > The way we do it, at least on powerpc which is PIPT, is to keep track on > > a per-page basis, whether a given page is clean for execution using > > PG_arch1 bit. This bit is cleared when a new page is popped into the > > page cache, and we clear it from flush_dcache_page() iirc (you may want > > to dbl check I don't have the code at hand right now, or rather, I do > > but I'm to lazy to look right now :-) > > We do the same on ARM. The problem with most (all) HCD drivers that do > PIO is that they copy the data to the transfer buffer but there is no > call in this driver to flush_dcache_page(). The upper mass storage or > filesystem layers don't call this function either, so there isn't > anything that would set the PG_arch1 bit. > > --=20 > Catalin > -- > IMPORTANT NOTICE: The contents of this email and any attachments are > confidential and may also be privileged. If you are not the intended > recipient, please notify the sender immediately and do not disclose > the contents to any other person, use it for any purpose, or store or > copy the information in any medium. Thank you. > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
