On Thu, 24 Jul 2008 00:10:33 +0200 Joerg Roedel <joro@xxxxxxxxxx> wrote: > On Wed, Jul 23, 2008 at 07:19:43AM -0400, Prarit Bhargava wrote: > > pci_alloc_consistent/dma_alloc_coherent does not return size aligned > > addresses. > > > > >From Documentation/DMA-mapping.txt: > > > > "pci_alloc_consistent returns two values: the virtual address which you > > can use to access it from the CPU and dma_handle which you pass to the > > card. > > > > The cpu return address and the DMA bus master address are both > > guaranteed to be aligned to the smallest PAGE_SIZE order which > > is greater than or equal to the requested size. This invariant > > exists (for example) to guarantee that if you allocate a chunk > > which is smaller than or equal to 64 kilobytes, the extent of the > > buffer you receive will not cross a 64K boundary." > > Interesting. Have you experienced any problems because of that > misbehavior in the GART code? AMD IOMMU currently also violates this > requirement. I will send a patch to fix that there too. IIRC, only PARISC and POWER IOMMUs follow the above rule. So I also wondered what problem he hit. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
