[Cbe-oss-dev] [patch 11/11] powerpc/cell: Add DMA_ATTR_STRONG_ORDERING dma attribute and use in IOMMU code

[Benjamin Herrenschmidt]

On Sat, 2008-07-05 at 15:43 +1000, Michael Ellerman wrote:
> > The current Cell IOMMU implementation sets the IOPTE_SO_RW bits in all IOTPEs
> > (for both the dynamic and fixed mappings) which enforces strong ordering of
> > both reads and writes. This patch makes the default behaviour weak ordering
> > (the IOPTE_SO_RW bits not set) and to request a strongly ordered mapping the
> > new DMA_ATTR_STRONG_ORDERING needs to be used.
> 
> We're sure that's safe?

I'd say it's not...

Ben.