Re: [Xen-devel] Problems accessing passthrough PCI device

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Nov 13, 2014 at 02:49:07PM -0300, Simon Martin wrote:
> Hello Jan,
> 
> >>
> >> Yes,  the  first thing I do in the driver is set the PCI configuration
> >> access  bits to 7 that should enable IO space, Memory Space and Master
> >> BUS access.
> >> 
> >> As  a  test I disabled this and all reads to the PCI device return -1,
> >> even the first one.
> 
> > I implied your earlier statement to mean that. But - did you also
> > verify that the three flags actually end up set (ideally from both
> > DomU and Dom0 perspective)? The PCI backend may be screwing
> > up things...
> 
> Yes I do verify the write. How do I check this from Dom0?

You can crank up the debug volume in xen-pciback. Recompile the kernel
and put '#define DEBUG 1' at the start of the .c files.

Interestingly enough I saw this issue as well - and it looked to me
that Xen pciback was stuck in '7' state (Reconfiguring) and never
excited it.

But I hadn't had a chance to dig in this.

> 
> >> I  agree,  this looks more than a hang than a crash. I've just found a
> >> link to the USB debug cable. I've ordered one but it will take a while
> 
> > And I hope you first verified that your system meets the criteria
> > for this to work in the first place?
> 
> I followed the checks in the Kernel earlyprintk debugging HOWTO, i.e.
> lspci -vvv to check the USB debug capability, and it verified. The
> device is ordered and now just to wait....
> 
> 
> -- 
> Best regards,
>  Simon                            mailto:furryfuttock@xxxxxxxxx
> 
> 
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