Re: can device drivers return non-ram via vm_ops->nopage?

From: Christoph Hellwig
Date: Sun Mar 21 2004 - 15:52:20 EST


On Sun, Mar 21, 2004 at 08:45:14PM +0000, David Woodhouse wrote:
> There are machines where DMA to/from main memory _cannot_ be coherent
> but we have some memory elsewhere, perhaps some SRAM which itself is
> hanging off an I/O bus somewhere, which can be used. One of my toys is
> currently running with dma_alloc_coherent() giving out memory from a PCI
> video card, in fact.
>
> Using a PFN should be OK.

And what exactly is a PFN without associated struct page supposed to mean?

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