Re: consistent_sync_for_cpu() and friends on ppc32

From: Benjamin Herrenschmidt
Date: Mon Mar 15 2004 - 17:10:41 EST

> Ben, can you work this out? I can make it compile by just making the
> _for_cpu and _for_device routines behave identically to what the
> consisten_sync{,_page}() stuff does now. But I'd much rather a ppc32
> person implement it correctly and optimally.
> In short, the _for_device routines should make sure cacheable data in
> the cpu is fully visible to the DMA device, and _for_cpu should make
> sure all device DMA is visible to the processor.

Yup, it depends for what CPU the kernel is compiled, normal desktop
CPUs are completely coherent, so this will be a no-op, but 4xx/8xx
embedded CPUs will need something better. I'll have a look today


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