Re: DMA bus-master writes & CPU cache question

Philip Blundell (pb@nexus.co.uk)
Mon, 12 Jul 1999 12:51:37 +0100


>Should CPU cache affect reading data from the DMA area, i.e.
>may some buffering effect or data inconherence appear? If so,
>what are the options?

This depends on your architecture. Intel platforms are fully DMA coherent;
the chipset snoops on DMA cycles and flushes the cache as required to maintain
a consistent view. On some other machines this is not the case and you must
deal with the caches by hand (see, for example,
include/asm-arm/proc-armv/io.h).

p.

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