Re: How to efficiently handle DMA and cache on ARMv7 ? (was "Isget_user_pages() enough to prevent pages from being swapped out ?")

[Robin Holt]

On Fri, Aug 07, 2009 at 02:07:43PM +0200, Laurent Desnogues wrote:
> On Fri, Aug 7, 2009 at 11:54 AM, Jamie Lokier<jamie@xxxxxxxxxxxxx> wrote:
> >
> > 1. Does the architecture not prevent speculative instruction
> > prefetches from crossing a page boundary?  It would be handy under the
> > circumstances.
> 
> There's no such restriction in ARMv7 architecture.

Doesn't it prevent them for uncached areas?  I _THOUGHT_ there was an
alloc_consistent (or something like that) call on ARM which gave you
an uncached mapping where you could do DMA.  I also thought there was
a dma_* set of functions which remapped as uncached before DMA begins
and remapped as normal after DMA has been completed.

Sorry for the fuzzy recollection.  I am dredging from 2.6.21 timeframe.

Robin
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