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SubjectRe: 2.6.18-rc5-mm1 unusual IRQ number for VIA device
Jay Cliburn wrote:
> Robert Hancock wrote:
>> Jay Cliburn wrote:
>>> Jay Cliburn wrote:
>>>> Running 2.6.18-rc5.mm1 on an Asus M2V mainboard with dual-core
>>>> Athlon cpu, the onboard audio device gets assigned and IRQ of 8410.
>>>> Under 2.6.18-rc4-mm3, the same device gets assigned IRQ 17. Is this
>>>> a way to get around this?
>>>
>>> What I meant to ask is: Is there a way to get around this?
>>>
>>> Thanks,
>>> Jay
>>
>> What do you think needs to be "gotten around"? It is using MSI
>> interrupts, I think that the IRQ numbers will be different.
>>
> I'll have to go research what MSI interrupts are. Thanks for the pointer.

Nothing I've read about MSI so far indicates that an IRQ number greater
than 255 is permissible, yet this device gets assigned an IRQ number of
8,410 when MSI is enabled. Booting 2.6.18-rc5-mm1 with pci=nomsi causes
the device to be assigned IRQ 17 instead of 8410.

The problem with the large IRQ number is made manifest in Fedora's
irqbalance program, which is run as an init script. An array is built
in that program that's indexed by IRQ number, with a max of 255. When
the program attempts to index element 8410, it segfaults.

Are IRQ numbers greater than 255 allowed with MSI?

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