On 2/6/2007 8:56 AM, Andi Kleen wrote: >> > From: David Moore <[EMAIL PROTECTED]> ... >> > It fixes real crashes: >> > http://lists.opensuse.org/opensuse-bugs/2006-12/msg02943.html >> > http://qa.mandriva.com/show_bug.cgi?id=28224 >> > http://www.pchdtv.com/forum/viewtopic.php?t=2063&sid=a959a14a4c2db0eebaab7b0df56103ce >> > >> > --- linux-2.6.19.x86_64/lib/swiotlb.c.orig 2007-02-04 13:18:41.000000000 >> > -0500 >> > +++ linux-2.6.19.x86_64/lib/swiotlb.c 2007-02-04 13:19:43.000000000 >> > -0500 >> > @@ -750,7 +750,7 @@ swiotlb_sync_sg(struct device *hwdev, st >> > >> > for (i = 0; i < nelems; i++, sg++) >> > if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg)) >> > - sync_single(hwdev, (void *) sg->dma_address, >> > + sync_single(hwdev, phys_to_virt(sg->dma_address), >> > sg->dma_length, dir, target); >> > } ... > Sounds weird. If this really didn't work much more should be broken > (e.g. no cdroms/sound on Intel x86-64 boxes with >4GB)
Yes, it's weird; e.g. it seems that reports of that on linux1394-user and -devel came in only recently. But I may have missed something. (OTOH, this bug was partially hidden for FireWire users because one of the relevant FireWire drivers was lacking respective _sync_sg calls.) > I'm a little sceptical. Perhaps the TV driver is doing something bogus > here? sync_single() definitely wants a virtual address there. sg->dma_address is a physical address. The bug and the fix are obvious. Unfortunately an author of lib/swiotlb.c chose to call many variables holding *virtual* addresses "dma_addr". Note how that file at the same time contains variables like "dma_addr_t dma_handle". A recipe for disaster. > Also I haven't heard of this problem before at all and I'm sure I would > have if sounds/cdroms were broken. > > Shouldn't be applied without further analysis. Maybe some recent changes elsewhere cause more frequent use of swiotlb-driven bounce buffers? That should be verified. Or maybe people are deploying affected hardware more often now? -- Stefan Richter -=====-=-=== --=- --==- http://arcgraph.de/sr/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/