On 05/24/2013 03:44 PM, Matthew Fornero wrote:
(Remember, this is not the adapter on my motherboard, but just something I
am plugging in for test purposes.) When I'm running vanilla linux (3.5.7)
with this configuration, everything seems to work fine (the ethernet card,
the mouse/keyboard, and no spurious interrupts). Under xenomai, the
ethernet card works, but within a few seconds the mouse and keyboard become
extremely delayed as I mentioned in a previous email.
Have you been able to look at dmesg output (or /var/log/message) after
the USB mouse and keyboard stop responding?
Nothing looks unusual in dmesg or /var/log/syslog other than:
[ 26.589844] I-pipe: spurious interrupt 32
[ 36.596341] I-pipe: spurious interrupt 32
I get at least one of these messages (and sometimes two) every time I boot a
Xenomai kernel on this machine, even if I don't see the mouse/keyboard issue,
and even if the secondary PCI ethernet card works (IRQ 17). The timing of the
second spurious interrupt message could be coincident with the mouse/keyboard
issue in this particular case, but I'm not sure.
This sounds very similar
to an issue we had where a real-time PCI device was sharing an
interrupt with one of the USB controllers.
I'm not running any realtime code at the time of this test other than what runs
when the machine is idle. If there is something like that going on, it's not
obvious to me. I agree the behavior seems similar to the case you mentioned.
I have experienced cases like that as well in the past.
As a workaround, is it an option to simply use a PCIe network card?
This will give you an MSI interrupt that won't conflict with any other
devices in your system.
I don't have a PCIe network card (other than the primary one on the
motherboard), but I did try putting the PCI card in a PCIe-PCI adapter. As you
mentioned, it was assigned it's own IRQ (28). This is the configuration I used
when I experienced the mouse/keyboard issue I mentioned above, so I don't see
how the problem could be due to the sharing of the network card IRQ, but it
could possibly be due to the sharing of a USB IRQ. The original problem of the
PCI network card not functioning when in the IRQ 16 slot could also be due to
some kind of IRQ sharing issue, though.
I recall seeing some concerns with using MSI
for real-time interrupts under Xenomai, but I believe it can be done
successfully on x86 if you observe a few precautions (maybe Jan Kiszka
can comment?). We've successfully used MSI for non-real time
interrupts (ethernet cards) on many of our platforms.
I have used MSI for ethernet cards on other RT systems as well. Even if I can
get a PCIe network card working without the USB issues I experienced above, I
will eventually need to use both PCI slots (IRQs 16 and 17) for RT serial
cards, so I need figure out what's going on with those IRQ lines.
It seems to me that there's something fundamentally wrong with my system, since
both USB and ethernet interrupts seem to be causing problems, depending on what
IRQs are being utilized.
-Matt
Thanks for the response, Matt!
-Jeff
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