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

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Mar 10, 2011 at 04:07:59PM +0000, Ian Campbell wrote:
> Changes since last time:
>       * correct return value of xen_irq_from_pirq
>       * WARN if a pirq cannot be allocated for a legacy IRQ
>       * Updated checking comment of "xen: events: do not workaround
>         too-small nr_irqs"
> 
> The following series makes a few cleanups to the Xen IRQ infrastructure.
> The most important thing is that it removes the need to know about
> nr_irqs and in particular the reliance on nr_irqs being static.
> 
> Apart from being generally a good thing this is needed because in 2.6.39
> nr_irqs will be able to grow dynamically, specifically e7bcecb7b1d2
> "genirq: Make nr_irqs runtime expandable" from tip/core/irq is targeted
> at 2.6.39.
> 
> Dynamically growing nr_irqs also allows us to remove the workaround
> which eats into GSI space if a dynamic IRQ cannot be allocated.
> 
> There is no ideal sequencing of this series vs e7bcecb7b1d2 (most should
> have gone in before, but the penultimate patch really needed to be
> simultaneous) so I haven't bothered to try and pull anything from tip
> into this branch -- it should all be resolved during the merge window
> and bisection won't be too broken since the "eat into GSI space"
> workaround only appears to be needed on a small number of older
> platforms (qemu being the main exception).

<nods>
> 
> I have tested:
>       * Domain 0 on real h/w and under qemu
>       * PV guest, including migration and passthrough of both VF and PF.
>       * PVHVM guest, including migration and passthrough of both VF and
>         PF.

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

MSI and MSI-X devices work just fine in both Dom0 and DomU case so
it is something special with the legacy IRQs. Probably forgot something
simple...