Re: [PATCH V4 1/3] x86: introduce CONFIG_X86_DEV_DMA_OPS

From: H. Peter Anvin
Date: Thu Apr 12 2012 - 16:18:46 EST


On 04/12/2012 01:15 PM, Alessandro Rubini wrote:
>
> The current approach is using swiotlb and it works pretty well, though
> with a limit of 4MB of swiotlb area. I've been considering use of the
> DMA zone to this aim: internally I have some half-working thing that
> resuses the ISA DMA zone for our own aims, raising the DMA limit to
> 512MB.
>
> Do you think the approach may make sense? I use this basic
> thing in Kconfig, to rely on GFP_DMA for the rest:
>
> config MAX_DMA_PADDR
> int
> default 536870912 if MAX_DMA_PADDR_512M
> default 16777216
>
> config MAX_DMA_PADDR_512M
> bool
>
> (actually, we'd benefit from being able to use hex in defaults)
>
> Is this worth exploring, to possibly submit a patch in this direction?
>

Not as a compile-time patch.

-hpa


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