[PATCH][POWERPC] Workaround for iommu page alignment

Michael Ellerman michael at ellerman.id.au
Tue Jan 8 09:41:24 EST 2008

On Tue, 2008-01-08 at 08:45 +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.

I don't see in the code where you implement the "size > PAGE_SIZE"
condition. But I only just got back from holidays .. :)


Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
URL: <http://lists.ozlabs.org/pipermail/linuxppc-dev/attachments/20080108/febf8090/attachment.pgp>

More information about the Linuxppc-dev mailing list