qnx 6 io-net problems

We have a usb peripheral-side user mode driver running on IRQ 5 on a
advantec Pentium-III single board computer (rack 6U, compact PCI). We’re
running QNX neutrino 6. The chip’s sitting on the other side of 2 PCI
bridges, and works ok most of the time.

However there’s a scenario where it does not gracefully disconnect, which
causes a surprise disconnect and actually causes the host (running windows)
to bluescreen. Anyway that’s another problem; what’s concerning me is that
when this happens, the io-net daemon (which runs at quite high priority)
goes to 100% CPU and makes the system quite unresponsive. (It is possible
to su root and slay the daemon, but it takes about 5 minutes to type the
commands because the terminals run at lower priority than io-net and aren’t
particularly responsive!).
What I’m extremely puzzled by is that our USB chip is sitting on a custom
board on the cPCI bus, and runs using our own custom written user mode
driver; I don’t see how anything it does can effect the io-net daemon which
after all is only concerned with the ethernet cards, which we’re not
actually using in our software.

My only working hypothesis is that somehow the USB chip is going nuts and
hammering the hardware interrupt line, and that it’s possible that it’s
sharing this line with the ethernet cards.
At boot I can see that our chip is using IRQ 5, and the cards are IRQ 10 and
11, but I can’t see any way of finding out what the routing table looks like
to see how the PIRQ’s are related to the 4 hardware interrupt lines, INT#A
through INT#D - i.e. I want to find out if they’re actually sharing a
hardware interrupt line.
Are there any utilities in QNX which would allow me to monitor interrupt
traffic in any way? To see perhaps the interrupt counts, or latencies; to
examine the routing table even? I know I can see a lot of info about such
stuff in Linux by examining dmesg logs for instance.

Any ideas, or other possible insights, would be most greatfully appreciated!
Michael Tomlinson
Invetech Pty Ltd
Private Bag 44
495 Blackburn Road
Mount Waverley Vic 3149
Phone: 61 3 9211 7812 (phone)
Fax: 61 3 9211 7702 (facsimile)
e-mail: mjt@nospam!invetech.com.au

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