On 2011-07-28 18:56, Jan Kiszka wrote: > On 2011-07-27 20:49, Gilles Chanteperdrix wrote: >> On 07/22/2011 05:04 PM, Jan Kiszka wrote: >>> Hi Gilles, >>> >>> pulling assert_context.c into the common libxenomai created a problem >>> around picking the right __wrap_clock_gettime. As libpthread_rt depends >>> on libxenomai, the latter is loaded first and defines the debug version >>> of __wrap_clock_gettime as the default. There is no chance to pull the >>> posix skin implementation. >>> >>> I don't have a nice idea yes how to resolve this. Options are: >>> - drop __wrap_clock_gettime from assert_context.c (affects any skin >>> user != posix) >>> - put assert_context stuff into separate library again >>> - put __wrap_clock_gettime in all skin libs != posix >>> >>> I'm favoring the simplest approach ATM, ie. the first one. Other ideas? >> >> I agree, but I would have thought __attriibute__((weak)) takes care of >> this issue. > > The point is that once you have pulled in that weak symbol into a > process, the dynamic loader won't update it if a non-weak version is > pulled in via dlopen.
Fiddling with all options again, it turned out that the issue is also reproducible without any dlopen. This ordering is fine: -lpthread_rt -lxenomai This one does not work: -lxenomai -lpthread_rt Now the problematic ordering can be achieved in many ways, in our case by linking a top-level process first against a library with native+xenomai dependencies and then against one with pthread_rt+xenomai deps. That is resolvable by reordering, but only if you maintain this meta-information consistently (IOW, it's doomed to break accidentally again). So I've pushed a patch that replaces the code with a comment that explains the non-existence. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux _______________________________________________ Xenomai-core mailing list Xenomaifirstname.lastname@example.org https://mail.gna.org/listinfo/xenomai-core