Re: [PATCH][POWERPC] Workaround for iommu page alignment

On Tue, Jan 08, 2008 at 08:45:59AM +1100, Benjamin Herrenschmidt wrote:

Our iommu page size is currently always 4K. That means with our current
code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t
that is only 4K aligned.

This works fine in most cases except some infiniband HW it seems, where
they tell the HW about the page size and it ignores the low bits of the
DMA address.

This works around it by making our IOMMU code enforce a PAGE_SIZE alignment
for mappings of objects that are page aligned in the first place and whose
size is larger or equal to a page.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Acked-by: Olof Johansson <redacted>


-Olof