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From: David Miller <davem@davemloft.net>
Subject: Re: Using netconsole for debugging suspend/resume
Date: Mon, 12 Jun 2006 22:03:46 -0700 (PDT)
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From: Andi Kleen <ak@suse.de>
Date: Tue, 13 Jun 2006 06:54:14 +0200

> I guess if you use 1394 with remote DMA for other protocols (like
> video etc.) there must be some way for the subsystem to map
> the memory even on IOMMU systems. I admit I haven't dived that
> deeply into the 1394 subsystem so I don't know how that works.

Video-1394 has it's own driver, which does a consistent DMA
allocation, and then maps that into userspace using remap_pfn_range().
Entirely portable.

Strangely I don't even see any bus_to_virt() etc. calls in
the raw1394 driver, just these ptr2int() things...