Re: [Xen-devel] USB virt status --- Help please!!!

[harry <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

On Mon, 2005-11-14 at 09:56 +0000, Keir Fraser wrote:
> On 13 Nov 2005, at 18:28, Harry Butterworth wrote:
> 
> > Is this the right approach? Is the check in dma_map_single overzealous?
> 
> When running on Xen, just because Linux has allocated adjacent pages 
> from its 'physical' memory map, doesn't mean they really are physically 
> contiguous. For I/O we have to go to extra effort to really allocate 
> truly contiguous multi-page extents.
> 
> So your code is correct. If you can preallocate buffers then you could 
> do that with dma_alloc_coherent and that would guarantee contigous 
> buffers....

I'm given the buffers by the assorted USB drivers.  I could stage the
data using memcpy into my own buffer allocated using dma_alloc_coherent.
Or should I go through all the USB drivers and change the buffer
allocation?

> 
>   -- Keir
> 
> 
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