What about memory for streaming mappings. I know pci_map_single (and _sg) will
use bounce buffers on platforms without an IOMMU, but wouldn't it be nice if
this could also be ensured by the device driver to avoid uneccessary copying.
It could for example be solved with a GFP_32BIT flag or something (on IA64 I
know GFP_DMA is used in pci_alloc_consistent() to get memory below 4GB but that
can't be used on all platforms).
> On 64-bit platforms without CONFIG_HIGHMEM, kmalloc can return any
> pointer, but that is fine since your DMA mask will instruct the
> IOMMU layer of the platform to map it in the low 32-bits of DMA
> address space.
>
> If you follow DMA-mapping.txt to the letter, it will just work, trust
> us. :-)
Regards,
-- Steffen Persvold | Scalable Linux Systems | Try out the world's best mailto:sp@scali.com | http://www.scali.com | performing MPI implementation: Tel: (+47) 2262 8950 | Olaf Helsets vei 6 | - ScaMPI 1.13.8 - Fax: (+47) 2262 8951 | N0621 Oslo, NORWAY | >320MBytes/s and <4uS latency - 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/