Re: [Xenomai-help] Re : rt_printf with daemonized task

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
>> oliver.schlenker@domain.hid wrote:
>>>>> int main( int arc, char *argv[] ) { int i;
>>>>>
>>>>> rt_print_auto_init(1);
>>>>>
>>>>> rt_printf("--------------- TEST RT-PRINTF  1 ------------\n");
>>>>>
>>>>> sleep(1);
>>>>>
>>>>> daemon(0,0);
>>>>>
>>>>> rt_print_auto_init(1);
>>> Ok, understood, at least for the scenario where the rt_print feature
>>> is initialised befor the fork/daemon call. What I don't understand
>>> is, why it does not work if the rt_print feature is initialised after
>>> the fork / daemon.
>> From the way I understand your code, you never tried to initialize the
>> rt_print feature only after the fork, your code initializes it both
>> before and after.
>>
> 
> There are two initializations: The base init done via __rt_print_init on
> library loading and the one to be done per-thread via rt_print_init (or
> on first rt_printf). That printer thread is initialized via the former
> one. On fork, we do not need to re-run the full __rt_print_init
> (variables and resources are cloned on fork), we just need to spawn
> another printer thread.

Unless I am wrong, rtdk also maintains a list of the thread buffers
which need to be polled. After the fork, this list will be intact, but
the threads to which belong the buffers will no longer exist. So, IMO,
the fork handler should also free all these buffers and reset the list
to the empty state.

-- 
                                          Gilles