Re: [Xen-devel] Re: [GIT PATCH v2 0/14] xen: events: cleanups +ween off nr_irqs

From: Ian Campbell
Date: Fri Mar 11 2011 - 04:17:11 EST


On Fri, 2011-03-11 at 00:38 +0000, Konrad Rzeszutek Wilk wrote:
> > I am having difficulties with passthrough of an USB device. Somehow the
> > irq count is not going up at all (both in dom0 and domU) and it looks to
> > be doing just simple polling. I've rebased the xen-pciback to be on top
> > of your changes and apply cleanly. The whole lot is now in #master
>
> I think your patchset breaks the 'xc_physdev_map_pirq' call. Looks like
> libxl_pci.c reads from /sys/bus/pci/devices/<BDF>/irq to figure out what value
> to pass. With these patches we wouldn't neccessarily pass in the right
> PIRQ value. Any ideas?

I'll have to have a think. At best there's some confusing usage of the
term pirq in there. (which is not unexpected, various subsystems use it
for different things.)

Certainly I would never expect to read a Xen pirq out of /sys/.../irq
and that appears to be how this value is being used...

Ian.

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