Re: DMA API issues

[Jeff Garzik]

Russell King wrote:
> On Mon, Jun 21, 2004 at 03:35:42PM +0200, Takashi Iwai wrote:
> > Yes, the struct page pointer is needed for vma_ops.nopage in mmap on
> > ALSA.  So far, this is broken on some architectures like ARM.  We need
> > a proper conversion from virtual/bus pointer to a page struct.
>
>
> Please get away from your nopage implementation.  We've been around this
> before with Linus, and the conclusion was that it's up to architectures
> to provide a MMAP method for DMA memory, which _may_ use the nopage
> method if and only if it is appropriate for their implementation.


Can you elaborate?

When I was writing sound/oss/via82cxxx_audio.c, Linus specifically 
recommended using ->nopage, which worked out quite well (modulo cleaning 
up VM_xxx flags).

	Jeff


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