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).

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux

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