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Subject: Re: [Cbe-oss-dev] [patch 11/11] powerpc/cell: Add
	DMA_ATTR_STRONG_ORDERING dma attribute and use in IOMMU code
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: michael@ellerman.id.au
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Date: Sat, 05 Jul 2008 16:28:59 +1000
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Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
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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.