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SubjectRe: [RFC] dma: passing "attributes" to dma_map_* routines
akepner@sgi.com wrote:
> Waaay back in October I sent some patches for passing additional
> attributes to the dma_map_* routines:
>
> http://marc.info/?l=linux-kernel&m=119137949604365&w=2

Do I understand correctly?: A device and the CPUs communicate via two
separate memory areas: A data buffer and a status FIFO. The NUMA
interconnect may reorder accesses of the device to the areas. (Write
accesses? Read accesses? Both?)

To ensure synchronization between device and CPUs, you want to mark a
memory area which is to be dma-mapped with a flag which says: "Writes
to the memory region will cause in-flight DMA to be flushed". Whose
writes? A write access from the device or a write access from a CPU?
--
Stefan Richter
-=====-=-=== ==-- =--=-
http://arcgraph.de/sr/


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