Not getting interrupts from PCI express slot

Neel Natu neelnatu at
Wed Aug 4 21:24:14 UTC 2010


On Wed, Aug 4, 2010 at 12:29 PM, Hans Petter Selasky <hselasky at> wrote:
> On Wednesday 04 August 2010 21:13:55 Neel Natu wrote:
>> Hi,
>> On Wed, Aug 4, 2010 at 10:18 AM, Hans Petter Selasky <hselasky at>
> wrote:
>> > Hi,
>> >
>> > I'm not getting any interrupts from a PCI express slot. When I insert a
>> > device, no attach event is generated. If the device is present during
>> > boot the device is fully detected, but still no IRQ's. Is there anything
>> > I can do or test?
>> Is the driver using legacy INT-A style interrupt or MSI/MSI-X?
> I don't know. How can I find out. It is a PCI driver like EHCI.

I looked at the ehci_pci.c driver and it looks like it only requests
legacy interrupt. It may be that the legacy interrupt routing is
screwed up by the BIOS.

You can try a few things to narrow this down a bit:

% devinfo -ru: this will tell you which irq is being assigned to the ehci device

% vmstat -i: this will tell you the number of interrupts received on
that irq. It would be especially telling if you saw any stray
interrupts as it may indicate bad interrupt routing.

Hope this helps.


> --HPS

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