Re: [Xen-devel] Re: PCI passthrough stopped working, brainache!

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sat, 2011-10-15 at 11:54 +0100, Andy Burns wrote:
> On 15 October 2011 11:36, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> 
> > In general if a driver is correctly using the DMA API things should
> > never be within the swiotlb.
> 
> OK, they just looked coincidentally similar.
> 
> > I think you've got 8G of RAM so one thing which might be worth trying is
> > to give "mem=2G" (or perhaps 3G) on the hypervisor command line.
> 
> Yes I do have 8GB, will give it a try.
> 
> > I wonder if the hypervisor's "dma_bits" option has any relevance here?
> > Might be worth a go?
> 
> I noticed that parameter, but couldn't see much indication of sensible
> values, something a few bits less than 32 perhaps?

Anything <32 would be a good guess, maybe try 30? Even 32 might be
worthwhile to try (not sure what you are getting by default).

Ian.

> > In general I think these sorts cards use I2C extensively, i.e. the tuner
> > etc is on an i2c bus, so I wouldn't expect anything to work at all
> > without it.
> 
> Yes, that part of the card is working, w_scan can control the tuner
> and detect when it latches onto valid muxes, receiving the bulk
> datastream from the demodulator is the problem.



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