[ewg] Re: [ofa-general] Toward next OFED release (1.3)

[Gleb Natapov]

On Tue, Jun 26, 2007 at 10:47:16AM -0700, Roland Dreier wrote:
> 
>  > What about allowing to allocate coherent memory for CQ inside the kernel
>  > to fix issue with Altix machines?
> 
> 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?

--
			Gleb.