POSIX signal handling
Joel Sherrill
joel.sherrill at OARcorp.com
Tue Mar 31 16:05:44 UTC 2009
How about this version?
RTEMS is multi-threaded within a single process and no thread
had ever enabled SIGALRM.
This MIGHT be a buglet in relation to the default signal mask
but we would have to consult the Open Group specification to
be sure.
Sérgio Santos wrote:
> Thanks again for your kind answer.
>
> Actually we've had that very output... since the beginning :)
> Ever since the problem for us is we're expecting not the signal to be pending, but otherwise that the handler *sig_handler* runs when the signal is received!
>
> We're running the same code, and - glad to know by comparing - no problems coming from our makefile. So we'd expect something like the output in Linux (every second):
>
> [sbrotas at imaserver2 sigact]$ ./sigact
> HANDLER: caught SIGALRM
> SIGALRM not pending :)
>
> HANDLER: caught SIGALRM
> SIGALRM not pending :)
>
> ^C
> [sbrotas at imaserver2 sigact]$
>
> ---
> Best Regards
> Sérgio
>
>
>
>
>> -----Original Message-----
>> From: Joel Sherrill [mailto:joel.sherrill at OARcorp.com]
>> Sent: terça-feira, 31 de Março de 2009 14:11
>> To: Sérgio Santos
>> Cc: rtems-users at rtems.com
>> Subject: Re: POSIX signal handling
>>
>> Sérgio Santos wrote:
>>
>>> Hi, Joel
>>> I'm using qemu (mostly) but have tried running directly on the target
>>>
>> too.
>>
>>> Our current guess is some build configuration conflict or mistake, but
>>>
>> we're still to find what exactly. Still, we haven't debugged much for some
>> clues or looked at the rtems code.
>>
>> Runs for me. I attached my version of your code and the
>> Makefile.
>>
>> Built on an installed BSP like this:
>>
>>
>> RTEMS_MAKEFILE_PATH=/home/joel/rtems-4.10-work/bsp-install/i386-
>> rtems4.10/pc386
>> make clean all
>>
>> [joel at iceland sigaction]$ runqemu -i */*exe
>> Running o-optimize/sigaction.exe
>> Could not open '/dev/kqemu' - QEMU acceleration layer not activated: No
>> such file or directory
>> SIGALRM is pending
>>
>> SIGALRM is pending
>>
>> SIGALRM is pending
>>
>> SIGALRM is pending
>>
>> SIGALRM is pending
>>
>> SIGALRM is pending
>>
>> /home/joel/bin/runqemu: line 65: 15963 Killed ${QEMU}
>> ${ARGS}
>> Could not open '/dev/kqemu' - QEMU acceleration layer not activated: No
>> such file or directory
>> SIGALRM is pending
>>
>>
>>> Our option is now getting closer to drop POSIX and go for the RTEMS
>>>
>> classic API on the async signals matter in particular, and for the port of
>> our Linux app overall. Still we'll report any findings.
>>
>>>
>>> Thank you much
>>>
>>> Sérgio
>>>
>>>
>>>
>>>
>>>> -----Original Message-----
>>>> From: Joel Sherrill [mailto:joel.sherrill at OARcorp.com]
>>>> Sent: segunda-feira, 30 de Março de 2009 20:30
>>>> To: Sérgio Santos
>>>> Cc: rtems-users at rtems.com
>>>> Subject: Re: POSIX signal handling
>>>>
>>>> Sérgio Santos wrote:
>>>>
>>>>
>>>>>> -----Original Message-----
>>>>>> From: Joel Sherrill [mailto:joel.sherrill at OARcorp.com]
>>>>>> Sent: segunda-feira, 30 de Março de 2009 19:11
>>>>>> To: Sérgio Santos
>>>>>> Cc: rtems-users at rtems.com
>>>>>> Subject: Re: POSIX signal handling
>>>>>>
>>>>>> Sergios,
>>>>>>
>>>>>> I meant to ask.. Is it ok to include this in the RTEMS examples
>>>>>> as a simple example of alarm and signals?
>>>>>>
>>>>>>
>>>>>>
>>>>> Joel,
>>>>>
>>>>> Sure! Can't help feeling it's a privilege, despite the simplicity of
>>>>>
>> the
>>
>>>> code :) Nevertheless I must say I'd be happier if it would work at all
>>>>
>> in
>>
>>>> my system! (please see below)
>>>>
>>>>
>>>>>
>>>>>> Joel Sherrill wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> OK.. runs for me with the CVS head.
>>>>>>>
>>>>>>> You forget to include <rtems/confdefs.h> at the bottom after
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> CONFIGURE_INIT.
>>>>>>
>>>>>>
>>>>>>
>>>>> You're right in pointing this, it was actually an unfortunate typo...
>>>>>
>>>>>
>>>>>
>>>>>
>>>> :) I expected as much. :)
>>>>
>>>>
>>>>>>> And delete the timer configuration.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>> Done already! So a conclusion is still open for me, the code is ok,
>>>>>
>>>>>
>>>> configuration is (now) ok, but instead of the current 4.8.1, I should
>>>>
>> try
>>
>>>> it with the CVS head (4.9.99?)
>>>>
>>>>
>>>> How are you running it?
>>>>
>>>>
>>>>> Thanks again for your help,
>>>>>
>>>>> Sérgio
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>> Folks .. please consider support agreements. :-D
>>>>>>> --joel
>>>>>>>
>>>>>>> Sérgio Santos wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> Hello all,
>>>>>>>>
>>>>>>>> I'm using rtems 4.8.1, target is i386 (single core, with FC9),
>>>>>>>>
>> using
>>
>>>>>>>>
>>>>>> bsp's between pc386 and pc686 and the RTEMS makefile templates.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>> I have been trying to port a Linux based application to RTEMS and
>>>>>>>>
>>>>>>>>
>>>> found
>>>>
>>>>
>>>>>> at some point I couldn't get POSIX signal handlers (set with
>>>>>>
>> sigaction)
>>
>>>> to
>>>>
>>>>
>>>>>> ever execute. From what I've read in rtems-users and user docs, no
>>>>>> problems should arise from using POSIX asynchronous signal handling
>>>>>>
>> in
>>
>>>>>> RTEMS, so my guess is I'm making some naïve mistake on code or
>>>>>> configuration...
>>>>>>
>>>>>>
>>>>>>
>>>>>>>> Also, searching on the list, came across a similar problem, but
>>>>>>>>
>> this
>>
>>>>>>>>
>>>>>> was a unique case and a long while ago:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>> http://www.rtems.com/ml/rtems-users/2002/september/msg00015.html
>>>>>>>> Unfortunately that thread was not conclusive.
>>>>>>>>
>>>>>>>> After a few other tests I've got down to a simple test application
>>>>>>>>
>>>>>>>>
>>>> (see
>>>>
>>>>
>>>>>> below), similar to the code in the post I mentioned above: a thread
>>>>>>
>>>>>>
>>>> sets
>>>>
>>>>
>>>>>> sigaction and just does alarm(1), sleep(3) in a cycle. Alike the
>>>>>>
>> other
>>
>>>>>> tests, in RTEMS the handler never gets to run (although the signal
>>>>>> (SIGALRM) is seen pending); in Linux all tests will work.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>> POSIX was enabled in the build configuration:
>>>>>>>> ../../../rtems-4.8.1/c/configure --prefix=/opt/rtems-4.8 --
>>>>>>>>
>> host=i386-
>>
>>>>>>>>
>>>>>> rtems4.8 --build=i686-pc-linux-gnu --target=i386-rtems4.8 --enable-
>>>>>>
>>>>>>
>>>> posix -
>>>>
>>>>
>>>>>> -disable-itron --enable-networking --enable-cxx --enable-rtems-debug
>>>>>>
>> --
>>
>>>>>> enable-rdbg --enable-rtemsbsp=pc386 --with-target-subdir=i386-
>>>>>>
>> rtems4.8
>>
>>>> --
>>>>
>>>>
>>>>>> exec-prefix=/opt/rtems-4.8/i386-rtems4.8 --includedir=/opt/rtems-
>>>>>>
>>>>>>
>>>> 4.8/i386-
>>>>
>>>>
>>>>>> rtems4.8/include --cache-file=/dev/null --srcdir=../../../rtems-
>>>>>>
>> 4.8.1/c
>>
>>>>>>
>>>>>>>> I post below the src for the simple test, having the RTEMS
>>>>>>>>
>>>>>>>>
>>>> definitions
>>>>
>>>>
>>>>>> in the end.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>> Thanks in advance for your help!
>>>>>>>>
>>>>>>>> Sérgio Santos
>>>>>>>>
>>>>>>>>
>>>>>>>> --------------
>>>>>>>>
>>>>>>>>
>>>>>>>> #include <signal.h>
>>>>>>>> #include <stdio.h>
>>>>>>>> #include <unistd.h>
>>>>>>>> #include <stdlib.h>
>>>>>>>>
>>>>>>>> #include <bsp.h>
>>>>>>>>
>>>>>>>> void sig_handler(int sig){
>>>>>>>> switch(sig){
>>>>>>>> case SIGALRM:
>>>>>>>> printf("HANDLER: caught SIGALRM\n");
>>>>>>>> break;
>>>>>>>> default:
>>>>>>>> printf("Received unexpected signal (%d)\nBye!", sig);
>>>>>>>> exit(1);
>>>>>>>> }
>>>>>>>> }
>>>>>>>>
>>>>>>>> void sig_init(){
>>>>>>>>
>>>>>>>> int rc;
>>>>>>>> sigset_t sigset;
>>>>>>>> struct sigaction sigact;
>>>>>>>>
>>>>>>>> rc = sigemptyset(&sigset);
>>>>>>>> if (rc != 0) {
>>>>>>>> printf("Can't empty set\n");exit(1);
>>>>>>>> }
>>>>>>>>
>>>>>>>> sigact.sa_mask = sigset;
>>>>>>>> sigact.sa_flags = 0;
>>>>>>>> sigact.sa_handler = &sig_handler;
>>>>>>>>
>>>>>>>> rc = sigaction(SIGALRM, &sigact, NULL);
>>>>>>>> if (rc != 0) {
>>>>>>>> printf("Can't install handler\n"); exit(1);
>>>>>>>> }
>>>>>>>> }
>>>>>>>>
>>>>>>>> void *POSIX_Init(void *arg){
>>>>>>>>
>>>>>>>> int rc = 0;
>>>>>>>> sigset_t pendingset;
>>>>>>>>
>>>>>>>> sig_init();
>>>>>>>>
>>>>>>>> rc = sigemptyset(&pendingset);
>>>>>>>> if (rc != 0) {
>>>>>>>> printf("Can't empty set\n");exit(1);
>>>>>>>> }
>>>>>>>>
>>>>>>>> while(1){
>>>>>>>> alarm(1);
>>>>>>>> sleep(3);
>>>>>>>> sigpending(&pendingset);
>>>>>>>> printf("%s\n\n", ( sigismember(&pendingset, SIGALRM) ?
>>>>>>>> "SIGALRM is pending" : "SIGALRM not pending"
>>>>>>>>
>> ));
>>
>>>>>>>> }
>>>>>>>> return 0;
>>>>>>>> }
>>>>>>>>
>>>>>>>> #define CONFIGURE_MAXIMUM_POSIX_THREADS 10
>>>>>>>> #define CONFIGURE_MAXIMUM_POSIX_MUTEXES 10
>>>>>>>> #define CONFIGURE_MAXIMUM_POSIX_TIMERS 10
>>>>>>>> #define CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS 40
>>>>>>>>
>>>>>>>> #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
>>>>>>>> #define CONFIGURE_APPLICATION_NEEDS_TIMER_DRIVER
>>>>>>>> #define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
>>>>>>>> #define CONFIGURE_POSIX_INIT_THREAD_TABLE
>>>>>>>> #define CONFIGURE_INIT
>>>>>>>>
>>>>>>>> // EOF
>>>>>>>> ----
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> rtems-users mailing list
>>>>>>>> rtems-users at rtems.com
>>>>>>>> http://rtems.rtems.org/mailman/listinfo/rtems-users
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>> --
>>>>>> Joel Sherrill, Ph.D. Director of Research & Development
>>>>>> joel.sherrill at OARcorp.com On-Line Applications Research
>>>>>> Ask me about RTEMS: a free RTOS Huntsville AL 35805
>>>>>> Support Available (256) 722-9985
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>> --
>>>> Joel Sherrill, Ph.D. Director of Research & Development
>>>> joel.sherrill at OARcorp.com On-Line Applications Research
>>>> Ask me about RTEMS: a free RTOS Huntsville AL 35805
>>>> Support Available (256) 722-9985
>>>>
>>>>
>>>>
>>>
>> --
>> Joel Sherrill, Ph.D. Director of Research & Development
>> joel.sherrill at OARcorp.com On-Line Applications Research
>> Ask me about RTEMS: a free RTOS Huntsville AL 35805
>> Support Available (256) 722-9985
>>
>>
>
>
--
Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill at OARcorp.com On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35805
Support Available (256) 722-9985
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