On Mon, Jan 31, 2000 at 02:46:13PM +0000, David Woodhouse wrote:
>
> lkd@tantalophile.demon.co.uk said:
> > How much hardware can do _ISA_ scatter/gather DMA?
>
> Depends on how clever the motherboard chipset / ISA bridge is.
>
> Any DMA-capable ISA card in an Alpha, for example, is quite happily capable
> of scatter/gather DMA, and it doesn't even have to know a thing about it.
>
> The PCI/ISA bridge will perform any mapping it's asked to - but at the moment
> Linux doesn't use that capability, and just sets up a static mapping to the
> first 16Mb of RAM, AFAIK
It does in 2.3.41, at least on UltraSPARC. See Documentation/DMA-mapping.txt.
Richard Henderson has patches to make this work on Alpha as well, but it probably
needs there some more debugging and testing.
Cheers,
Jakub
___________________________________________________________________
Jakub Jelinek | jakub@redhat.com | http://sunsite.mff.cuni.cz/~jj
Linux version 2.3.41 on a sparc64 machine (1343.49 BogoMips)
___________________________________________________________________
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