Messages in this thread | | | Date | Fri, 7 Aug 2009 09:10:41 +0100 | From | Russell King - ARM Linux <> | 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 09:58:30AM +0200, Laurent Pinchart wrote: > Sorry about this, but I'm not sure to understand the speculative prefetching > cache issue completely.
The general case with speculative prefetching is that if memory is accessible, it can be prefetched.
In other words, if we mapped devices without NX (non-exec) set, the CPU can prefetch instructions from devices, causing random read accesses. Yes, I know it sounds crazy, but that's what I'm told _can_ happen.
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