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Date: Wed, 06 Jun 2012 15:53:17 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai] xenomai-2.6.0 instrumentation commands not executing
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: Xenomai@xenomai.org

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.

-- 
Philippe.