On 02/16/2015 08:11 PM, Jan Kiszka wrote:
> On 2015-02-16 19:52, Jan Kiszka wrote:
>> On 2015-02-16 18:52, Jan Kiszka wrote:
>>> On 2015-02-16 18:48, Philippe Gerum wrote:
>>>> On 02/16/2015 06:35 PM, Jan Kiszka wrote:
>>>>> The following changes since commit 
>>>>> 00d8a6f2e95453f61ae97b6587dba03bc91c7e1a:
>>>>>
>>>>>   arm/ipipe: Resolve trival merge conflicts (2015-01-14 17:00:22 +0100)
>>>>>
>>>>> are available in the git repository at:
>>>>>
>>>>>   git://git.xenomai.org/ipipe-jki 
>>>>>
>>>>> for you to fetch changes up to f982e48ce99e1bc9e71eac21830adac2db265c98:
>>>>>
>>>>>   x86/ipipe: Restore invocation of ipipe_unlock_irq from 
>>>>> startup_ioapic_irq (2015-02-16 18:22:21 +0100)
>>>>>
>>>>> All patches apply to 3.16 as well but weren't tested there yet. Still
>>>>> analyzing strange
>>>>>
>>>>> traps: (systemd)[1420] trap invalid opcode ip:7f4d138f612b 
>>>>> sp:7fff4fd8f568 error:0 in libpthread-2.19.so[7f4d138e5000+18000]
>>>>>
>>>>> on the target under 3.14...
>>>>>
>>>>
>>>> Register trashing on the fast call path (system_call_after_gs) maybe.
>>>> Forcing CONFIG_IPIPE_LEGACY there might help ruling this out.
>>>
>>> That's without any Xenomai configured. But I will check.
>>
>> This is where it traps in libpthread:
>>
>>    1112b:       c7 f8 00 00 00 00       xbeginq 11131 
>> <__lll_lock_elision+0x51>
>>
>> For some reason, glibc starts to believe it could use RTM on that
>> machine - although this is clearly not available (Haswell i7, thus a
>> buggy CPU). Need to understand which feature check goes wrong, and why
>> only on I-pipe enabled kernels.
>>
>> The good news is that I still have a similar and unresolved report from
>> early customer tests. That could solve their issues as well (they
>> caused massive domain migrations).
> 
> Wait - we were already one step further: a potential trigger for this
> behaviour is a nullified pthread mutex. The decision to take the TSX
> path is based on field in that struct, and 0 means transactional. Guess
> I need a better reproduction case than some systemd service.

Which glibc release are you running?

-- 
Philippe.

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