On 06/06/2012 05:03 PM, Philippe Gerum wrote:
> On 06/06/2012 04:27 PM, Gilles Chanteperdrix wrote:
>> On 06/06/2012 04:02 PM, Gilles Chanteperdrix wrote:
>>> On 06/06/2012 03:55 PM, Gilles Chanteperdrix wrote:
>>>> On 06/06/2012 03:53 PM, Philippe Gerum wrote:
>>>>> On 06/06/2012 03:41 PM, Gilles Chanteperdrix wrote:
>>>>>> On 06/06/2012 03:25 PM, Philippe Gerum wrote:
>>>>>>> On 06/06/2012 03:18 PM, Gilles Chanteperdrix wrote:
>>>>>>>> On 06/06/2012 02:28 PM, Philippe Gerum wrote:
>>>>>>>>> On 06/06/2012 11:48 AM, Philippe Gerum wrote:
>>>>>>>>>> On 06/06/2012 11:18 AM, ali hagigat wrote:
>>>>>>>>>>> Much appreciate for the reply, Mr. Gerum. Here is the result of ldd
>>>>>>>>>>> command:
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> http://www.xenomai.org/pipermail/xenomai-help/2011-12/msg00012.html
>>>>>>>>>
>>>>>>>>> Alternatively, this patch may work as well (not tested, but this
>>>>>>>>> looks like a former issue we had with aggressive optimizers):
>>>>>>>>>
>>>>>>>>> diff --git a/src/skins/posix/init.c b/src/skins/posix/init.c
>>>>>>>>> index 7a338a0..9c7849e 100644
>>>>>>>>> --- a/src/skins/posix/init.c
>>>>>>>>> +++ b/src/skins/posix/init.c
>>>>>>>>> @@ -43,6 +43,7 @@ void pse51_clock_init(int);
>>>>>>>>> static __attribute__ ((constructor))
>>>>>>>>> void __init_posix_interface(void)
>>>>>>>>> {
>>>>>>>>> + volatile pthread_t tid = pthread_self();
>>>>>>>>> #ifndef CONFIG_XENO_LIBS_DLOPEN
>>>>>>>>> struct sched_param parm;
>>>>>>>>> int policy;
>>>>>>>>> @@ -80,14 +81,14 @@ void __init_posix_interface(void)
>>>>>>>>>
>>>>>>>>> /* Don't use auto-shadowing if we are likely invoked from
>>>>>>>>> dlopen. */
>>>>>>>>> #ifndef CONFIG_XENO_LIBS_DLOPEN
>>>>>>>>> - err =
>>>>>>>>> __real_pthread_getschedparam(pthread_self(),&policy,&parm);
>>>>>>>>> + err = __real_pthread_getschedparam(tid,&policy,&parm);
>>>>>>>>> if (err) {
>>>>>>>>> fprintf(stderr, "Xenomai Posix skin init: "
>>>>>>>>> "pthread_getschedparam: %s\n", strerror(err));
>>>>>>>>> exit(EXIT_FAILURE);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> - err = __wrap_pthread_setschedparam(pthread_self(),
>>>>>>>>> policy,&parm);
>>>>>>>>> + err = __wrap_pthread_setschedparam(tid, policy,&parm);
>>>>>>>>> if (err) {
>>>>>>>>> fprintf(stderr, "Xenomai Posix skin init: "
>>>>>>>>> "pthread_setschedparam: %s\n", strerror(err));
>>>>>>>>
>>>>>>>> There should not be any issue here, as the pthread_self() is passed as
>>>>>>>> an argument to the called functions, the syscall is not inlined
>>>>>>>> directly.
>>>>>>>>
>>>>>>>
>>>>>>> Did you get any disassembly of the faulty code when suggesting
>>>>>>> -fno-omit-frame-pointer last time you did?
>>>>>>>
>>>>>> No, but I had experienced the problem first hand.
>>>>>>
>>>>>
>>>>> It would be interesting to know why we have to force a frame pointer in
>>>>> there. I'm not comfortable with voodoo fixing, that bug might bite later
>>>>> on as gcc's optimizer is unlikely to become less aggressive over time.
>>>>>
>>>> Ah this, I know. I have posted a mail where I explained the problem. I
>>>> am a bit in a short schedule here, will post the link tonight.
>>>>
>>> http://xenomai.org/pipermail/xenomai-core/2011-08/msg00029.html
>>>
>>
>> In the mails following this one, I found how to fix the assembly to work
>> in the omit-frame-pointer case. The real problem is that, at compilation
>> time, we have no command-line #defined variable telling us whether
>> compiling with frame pointers enabled. And it does not seem easy to
>> write a configure test script, which tests whether frame pointers are
>> enabled or not.
>>
>
> I'd suggest that at some point, we move all the syscall trampolines out
> of line, and specifically build the resulting file forcing
> -fno-omit-frame-pointer. Such inlining will always be fragile until we
> actually control the way that compilation unit is built, regardless of
> the general settings for CFLAGS.
>
In the current 2.6 repository, we force -fno-omit-frame-pointer on x86_32.
--
Gilles.
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