Lapo TIN wrote:
I have a problem with IRQs.
My pc has a CPU PentiumD945 (dual core) and a 2.6.19smp kernel.
I have two video acquisition board (four bt8t8 each) in the only two pci
slots of my motherboard. Thus I have a total of 8 bttv modules that are
working together, and the /proc/interrupts is as follows:
# cat /proc/interrupts
0: 13575 0 IO-APIC-edge timer
1: 2 0 IO-APIC-edge i8042
4: 11 0 IO-APIC-edge serial
8: 1 0 IO-APIC-edge rtc
9: 0 0 IO-APIC-fasteoi acpi
12: 4 0 IO-APIC-edge i8042
14: 22286 0 IO-APIC-edge ide0
17: 7073 2097 IO-APIC-fasteoi uhci_hcd:usb5, eth0
18: 2525 0 IO-APIC-fasteoi bttv0, bttv7
19: 2829 0 IO-APIC-fasteoi bttv1, bttv4
20: 2526 0 IO-APIC-fasteoi bttv2, bttv5
21: 2226 0 IO-APIC-fasteoi bttv3, bttv6
22: 2 0 IO-APIC-fasteoi ehci_hcd:usb1, uhci_hcd:usb4
23: 86 0 IO-APIC-fasteoi uhci_hcd:usb2
24: 0 0 IO-APIC-fasteoi uhci_hcd:usb3
NMI: 0 0
LOC: 13484 13502
You can see that IRQ18 is shared between bttv0 and bttv7, IRQ19 between
bttv1 and bttv4 and so on.
Sometimes it crashes. It seems a matter of conflict in IRQ.
With only one video board everything is ok, but with two, they shared irq
and something goes wrong...
How can I tell to the kernel to not to share the IRQ for these boards ?
I think (I don't know if I'm right) that this could be the problem.
I even tried with another motherboard, and doing cat /proc/interrupts the
situation was the same, except for 'eth0' that was together with bttv0 and
bttv7... so it was even worst ! it crashes after few minutes.
I tried to read IO-APIC.txt in Documentation/i386/ folder, but I didn't
understand how to avoid the coupling of IRQ.
You may be able to move one board to another slot, but looking at the
bandwidth I suspect you may need a server motherboard with multiple
busses, preferably running at 66MHz 64bit. I don't think this is a
interrupt problem, but you can just try capture on two channels which
share an interrupt, like bttv0 and bttv7 to verify that.
I think you are just running out of bus.
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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