From: harry <harry@hebutterworth.freeserve.co.uk>
To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk>,
xen-devel@lists.xensource.com, mark.williamson@cl.cam.ac.uk,
sanjay.kushwaha@gmail.com
Subject: Re: USB virt status --- Help please!!!
Date: Mon, 14 Nov 2005 10:12:06 +0000 [thread overview]
Message-ID: <1131963126.28635.3.camel@localhost.localdomain> (raw)
In-Reply-To: <aa8e1dea0e3038d0d50d615fe9049458@cl.cam.ac.uk>
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
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
next prev parent reply other threads:[~2005-11-14 10:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-11 23:23 USB virt status Ian Pratt
2005-11-13 18:28 ` USB virt status --- Help please!!! Harry Butterworth
2005-11-14 9:56 ` Keir Fraser
2005-11-14 10:12 ` harry [this message]
2005-11-14 10:27 ` harry
2005-11-14 10:33 ` Keir Fraser
2005-11-14 17:30 ` Stephen C. Tweedie
2005-11-14 18:42 ` Keir Fraser
2005-11-14 18:50 ` Stephen C. Tweedie
2005-11-14 20:36 ` Harry Butterworth
2005-11-14 21:00 ` Muli Ben-Yehuda
2005-11-14 21:46 ` Muli Ben-Yehuda
2005-11-15 10:23 ` Keir Fraser
2005-11-15 19:14 ` Muli Ben-Yehuda
-- strict thread matches above, loose matches on Subject: below --
2005-11-15 22:36 Ian Pratt
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