Re: [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce32bit DMA mapping"

From: Benjamin Herrenschmidt
Date: Mon Aug 06 2007 - 18:32:43 EST


On Mon, 2007-08-06 at 16:25 -0600, Robert Hancock wrote:
> > Anyway. For now I will simply go with what 2.6.23-rc has and what
> > 2.6.21 had: No dma_set_mask anywhere in the 1394 subsystem. We can
> > revisit this whenever an actual need arises.
>
> Not sure this is a very good idea. This seems rather likely to fail on
> x86_64 machines with >4GB of RAM for example..

Would it ? Isn't the default DMA mask for PCI devices set to 32 bits
anyway ? In which case, swiotlb will take care of the matter.

Cheers,
Ben.


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