On Mon, Jul 23, 2018 at 11:16:07PM +0100, Robin Murphy wrote: > Whilst the notion of an upstream DMA restriction is most commonly seen > in PCI host bridges saddled with a 32-bit native interface, a more > general version of the same issue can exist on complex SoCs where a bus > or point-to-point interconnect link from a device's DMA master interface > to another component along the path to memory (often an IOMMU) may carry > fewer address bits than the interfaces at both ends nominally support. > In order to properly deal with this, the first step is to expand the > dma_32bit_limit flag into an arbitrary mask. > > To minimise the impact on existing code, we'll make sure to only > consider this new mask valid if set. That makes sense anyway, since a > mask of zero would represent DMA not being wired up at all, and that > would be better handled by not providing valid ops in the first place. > > Signed-off-by: Robin Murphy <robin.mur...@arm.com>
Looks good, Reviewed-by: Christoph Hellwig <h...@lst.de> _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
