[ewg] Re: [ofa-general] Toward next OFED release (1.3)
Roland Dreier
rdreier at cisco.com
Tue Jun 26 11:33:04 PDT 2007
> > Sorry... I've been remiss in posting about this. I would actually
> > prefer to see an extension to the dma_map_sg() interface (a new flag
> > perhaps?) that would set the right magic bit in the DMA address on
> > altix. The refactoring of ib_umem_get() to be called by low-level
> > drivers makes this a fairly clean approach, and it avoids the problems
> > with using dma_alloc_coherent() to allocate userspace buffers (for
> > example, dma_alloc_coherent() uses up kernel virtual addresses, which
> > may be scarce on 32 bit architectures).
> While this make sense it would be hard to push into the kernel proper.
> Or no? Are you going to do that?
I don't think I'm willing to merge a fix that uses dma_alloc_coherent()
inside the kernel so this alternate fix is probably easier to merge.
Yes, it does mean an extension to the DMA mapping API but I think
getting that right will be useful in terms of making sure what we're
doing really makes sense.
- R.
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