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Re: [Xen-devel] PCI pass-through / MSI question: Is 30(hex) the lower limit for pirq?

  • To: Pasi Kärkkäinen <pasik@xxxxxx>
  • From: Dante Cinco <dantecinco@xxxxxxxxx>
  • Date: Fri, 28 May 2010 13:51:01 -0700
  • Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>
  • Delivery-date: Fri, 28 May 2010 13:52:08 -0700
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Pasi, Jan,

Thank for your help. Adding the extra_guest_irqs Xen boot option resolved the issue I was having with the 8G QLogic card in the Windows domU. Each of the 2 QLogic devices requires 32 IRQs when MSI-X is enabled so I set the value to 80 (16 extra).


On 5/28/2010 1:50 AM, Pasi Kärkkäinen wrote:
On Fri, May 28, 2010 at 08:30:40AM +0100, Jan Beulich wrote:
On 28.05.10 at 01:29, Dante Cinco<dantecinco@xxxxxxxxx>  wrote:
I'm trying to bring up a Windows domU with PCI pass-through and it looks
like Xen is running out of pirqs (see log below). I'm using Xen 4.0.0 and
dom0 pv-ops and pci-stub to hide the PCIe device.

It looks like the first available pirq is 4e(hex) and the last available is
30(hex) and after that, Xen returns an msix error. What's the consequence of
running out of pirqs?
Did you try the extra_guest_irqs= Xen command line option to
increase the number of PIRQs (defaulting to 32) for the guest?

I added this xen.gz option to:

-- Pasi

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