[HEADS UP] planned change to <asm-generic/dma-mapping.h> will cause arch breakage

[Christoph Hellwig <hch@lst.de>]

To allow including <linux/dma-mapping.h> in generic code the default
implemtation of the dma-mapping API in terms of the PCI API will have
to go away.  What does this mean for your architecture?

 - If your architecture doesn't use <asm-generic/dma-mapping.h>
   (arm, i386, parisc):  Nothing.
 - If your architecture doesn't support PCI (cris, s390. um):
   Nothing, except that your arch won't break anymore if somsone
   includes dma-mapping.h in generic code.  But it would be cool to move
   over your dma-capable busses to the dma-mapping API...
 - Everyone else:  Unless you properly implement the dma-mapping in
   your architecture the dma_* APIs won't work anymore for you.
   The simplest way to get support for it on pci busses is to change
   your implementation of the pci_* dma functions to the dma_* prototypes
   and add the following to their top:

	struct pci_dev *pdev = to_pci_dev(dev);

   and maybe

	BUG_ON(dev->bus != &pci_bus_type);

   Of course it would be much nicer if you could add support for the
   dma-mapping API to your other dma-capable busses..