Messages in this thread | | | Date | Fri, 7 Aug 2009 08:15:01 -0500 | From | Robin Holt <> | Subject | Re: How to efficiently handle DMA and cache on ARMv7 ? (was "Is get_user_pages() enough to prevent pages from being swapped out ?") |
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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@shareable.org> 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.
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