[linux-dvb] Re: IRQ issues with Nova-S CI when using CI Module

Andrew de Quincey adq_dvb at lidskialf.net
Mon Jul 25 17:24:24 CEST 2005

On Monday 25 July 2005 15:08, Michael Ditum wrote:
> Thanks for that Andrew, I'll try the latest CVS version in a while,
> I'm currently having trouble getting 2.6.13 booting at the moment...
> I'll have a look to see if your modification are ok once I've got that
> booting.
> Back to the other IRQ problem...
> I've done some more testing. I've now tested it on 2 servers which
> have similar, but not exactly the same, hardware. It occurs on our HP
> Proliant ML350 G4 and our HP Proliant ML370 G4.
> The problem only seems to occur on bootup from a poweroff. If I
> reboot, it then starts working correctly until I power it off.
> 2 different print outs to /var/log/messages depending on if the card
> has a CI or not.
> With:
> Jul 13 16:27:34 bloodhound kernel: Uhhuh. NMI received. Dazed and
> confused, but trying to continue
> Jul 13 16:27:34 bloodhound kernel: You probably have a hardware
> problem with your RAM chips
> Jul 13 16:27:34 bloodhound kernel: irq 11: nobody cared!
> Jul 13 16:27:34 bloodhound kernel:  [<c014efc4>] __report_bad_irq+0x24/0x7d
> Jul 13 16:27:34 bloodhound kernel:  [<c014f0a6>] note_interrupt+0x6b/0x89


>  10:      11805          XT-PIC  ioc0, ioc1, saa7146 (0), saa7146 (1),
> uhci_hcd:usb3, uhci_hcd:usb4
>  11:    3900000          XT-PIC  ehci_hcd:usb1, uhci_hcd:usb2,
> uhci_hcd:usb5, eth0


Bear with me - its been a year or so since I messed about with ACPI.

So you're getting IRQ 11 when you shouldn't be effectively. Since its 
happening on two servers, this is likely either a kernel bug or a BIOS bug. I 
take it the cards work fine on other (non-HP) machines?

AFAIR, the motherboard chipset of modern machines can usually be reprogrammed 
to route IRQs to a variety of destinations. This looks like linux thinks the 
IRQ for your DVB cards is 10 when actually your motherboard chipset is set up 
for IRQ 11. 

In legacy (non-ACPI) mode linux has a set of functions for each chipset for 
configuring IRQ routing. It may be that there is a bug in this, or else this 
is a newer chipset it doesn't quite know everything about (some manufactuers 
don't release this documentation :( ). Or else your BIOS is setting it up 
wrongly... I'm sorry I can't remember the exact details.

You're running your motherboard in legacy (non-ACPI) mode. Have you tried 
using ACPI under linux? Under ACPI, linux executes a set of virtual machine 
instructions on startup. This configures the hardware without linux having to 
have specific support for that chipset.

Another possibility might be to upgrade the bios.

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