>>> On 19.11.14 at 17:02, <david.vra...@citrix.com> wrote: > On a Xen PV guest the DMA addresses and physical addresses are not 1:1 > (such as Xen PV guests) and the generic dma_get_required_mask() does > not return the correct mask (since it uses max_pfn). > > Some device drivers (such as mptsas, mpt2sas) use > dma_get_required_mask() to set the device's DMA mask to allow them to > use only 32-bit DMA addresses in hardware structures. This results in > unnecessary use of the SWIOTLB if DMA addresses are more than 32-bits, > impacting performance significantly. > > Provide a get_required_mask op that uses the maximum MFN to calculate > the DMA mask. > > Signed-off-by: David Vrabel <david.vra...@citrix.com>
Reviewed-by: Jan Beulich <jbeul...@suse.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
