On 06/08/2012 11:31 AM, Philippe Gerum wrote: > On 06/08/2012 11:29 AM, Philippe Gerum wrote: >> On 06/08/2012 11:25 AM, Gilles Chanteperdrix wrote: >>> On 06/08/2012 11:20 AM, Philippe Gerum wrote: >>>> On 06/06/2012 08:00 PM, Gilles Chanteperdrix wrote: >>>>> On 06/06/2012 07:57 PM, Gilles Chanteperdrix wrote: >>>>>> On 06/06/2012 05:21 PM, Philippe Gerum wrote: >>>>>>> On 06/06/2012 05:15 PM, Gilles Chanteperdrix wrote: >>>>>>>> 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. >>>>>>>> >>>>>>> >>>>>>> Yes, but that is crappy. The point is that we don't want to force >>>>>>> this >>>>>>> for all userland bits. We'd only need this for syscall trampolines. >>>>>>> >>>>>> We currently have different flags for compiling xenomai than for >>>>>> passing >>>>>> to the applications (via xeno-config). The problem is that I am not >>>>>> sure >>>>>> it will not break for instance calling "backtrace" in gdb when >>>>>> breaking >>>>>> inside a xenomai function. >>>>>> >>>>> (mixing code compiled without frame pointers with code compiled with >>>>> frame pointers I mean). >>>>> >>>> >>>> The only issue is with frame elimination starting with -O2 and above, >>>> otherwise the backtraces are clean over gdb (just checked), at least >>>> there does not seem to be any additional problem introduced by mixing bp >>>> and no-bp. At any rate, -O0 -g is recommended to get clean and detailed >>>> (back)traces anyway, and this is what we pick when --enable-debug is >>>> given. >>>> >>>> We should move each existing inline XENOMAI_SYS/SKINCALL macro into its >>>> own C trampoline, group all trampolines into separate compilation units, >>>> and build each of these units with -fno-omit-frame-pointer >>>> unconditionally. >>>> >>>> -forge is a good candidate for this, since the number of syscall >>>> trampolines shrunk dramatically compared to 2.x. If any issue would be >>>> easily detected based on the output of the new "slackspot" tracer we >>>> have there. >>>> >>> It looks to me like we can simply build xenomai libraries with >>> -fno-omit-frame-pointer, and compile the rest without this option. After >>> all, implementation of xenomai services are little more than syscall >>> trampolines. >>> >> >> This is true for 2.x, however -forge will need the other approach. >> > > Unless you only mean lib/cobalt for 3.x, in which case I would agree. > I was thinking 2.x. But yes, we can do the same with lib/cobalt.
-- Gilles. _______________________________________________ Xenomai mailing list Xenomai@xenomai.org http://www.xenomai.org/mailman/listinfo/xenomai