[RFC] ARM DMA mapping TODO, v1

[Alan Cox]

> I believe that the PC graphics cards that have noncoherent DMA mappings
> are all of the unified memory (integrated into the northbridge) kind,
> so they are not on the same host bridge as all regular PCI devices,
> even if they appear as a PCI device.

The AGP GART is not coherent on a lot of systems - not necessarily
unified memory though, it can be a plug in AGP card too.
The GART is basically an IOMMU (and indeed in the later AMD case used
exactly as that)