Messages in this thread | | | Date | Mon, 10 Jun 2002 10:29:09 -0700 | From | Tom Rini <> | Subject | Re: PCI DMA to small buffers on cache-incoherent arch |
| |
On Mon, Jun 10, 2002 at 07:22:26PM +0200, Oliver Neukum wrote: > > > > So is the consensus now that in general drivers should make sure any > > > buffers passed to pci_map/unmap are aligned to SMP_CACHE_BYTES (and a > > > multiple of SMP_CACHE_BYTES in size)? In other words if a driver uses > > > an unaligned buffer it should be fixed unless we can prove (and > > > document in a comment :) that it won't cause problems on an arch > > > without cache coherency and with a writeback cache. > > > > And how about we don't call it SMP_CACHE_BYTES too? The processors > > where this matters certainly aren't doing SMP... > > Definitely we should call it something different so we can limit it to > architectures that need it.
No. We should just make it come out to a nop for arches that don't need it. Otherwise we'll end up with ugly things like: #ifdef CONFIG_NOT_CACHE_COHERENT ... #else ... #endif
All over things like USB...
-- Tom Rini (TR1265) http://gate.crashing.org/~trini/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |