Re: [Xenomai] (Boot)-problems with (current) ipipe patch on AMD FX 61000 - 2.6.38.8 & 3.5.7

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2013-02-19 13:30, Gilles Chanteperdrix wrote:
> On 02/19/2013 01:22 PM, Jan Kiszka wrote:
> 
>> On 2013-02-19 13:07, Gilles Chanteperdrix wrote:
>>> On 02/19/2013 01:05 PM, Jan Kiszka wrote:
>>>
>>>> On 2013-02-19 12:22, Manuel Huber wrote:
>>>>> Thanks for your reply and sorry for the delay ;)
>>>>> I have tried disabling the options and attached the logs. It still fails :(
>>>>>
>>>>> I hope it's okay to attach so many files... I can also add the config
>>>>> files for
>>>>> every build if that helps.
>>>>
>>>> I'll try your config later, though in a different environment. If I'm
>>>> unable to reproduce, I'll provide further instrumentation suggestions.
>>>>
>>>> Gilles instrumentation confirmed that the CPU is taking a standard
>>>> external IRQ (#23: 0x37-FIRST_EXTERNAL_VECTOR). I suspect we are
>>>> enabling hardware IRQs too early during the boot of secondary CPUs,
>>>> causing this BUG as not all data structures are initialized yet. What
>>>> enables then can be some code that we do not run normally, on x86-64 or
>>>> maybe also x86-32 unless using your .config and/or your hardware.
>>>
>>>
>>> Remember that we have had such problems with grub2, so, the error could
>>> depend on the bootloader, for instance a network-aware bootloader could
>>> keep the network interface configured and we would take an interrupt
>>> when re-enabling interrupts.
>>
>> Possibly, but I don't see yet how Linux (3.5.7) would behave better in
>> this case. It should rather access the irq_desc array with a negative
>> index. And that suggests there is still an I-pipe factor involved that
>> makes this bug possible (the BUG_ON just catches it).
> 
> 
> Maybe because Linux only unmask the interrupt after request_irq has
> installed a handler?

Does I-pipe do this, specifically that early during boot?

Well, I can try injecting a spurious IRQ7 through QEMU to see what happens.

Jan

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