Hello Lars,
Thanks for trying out... On 06/19/2011 10:34 PM, Lars Segerlund wrote:
command line ...
root@smurf:/home/ls/src/emc/emc2-dev/src/hal# chrt 99 ./shm_interface_test
Error while shmget
Semaphore value is 0
Waiting one second, then until semaphore gets released
Segmenteringsfel
dmesg ...
[ 3579.723705] shm_interface_t[2462]: segfault at ffffffffa76ad000 ip
0000000000400d14 sp 00007fff128c4600 error 6 in
shm_interface_test[400000+2000]
I tried running with gdb but didn't get anything interesting, and it's
not a lot.
I tried strace also
arch_prctl(ARCH_SET_FS, 0x7fcf1a3d9700) = 0
mprotect(0x7fcf19b98000, 16384, PROT_READ) = 0
mprotect(0x7fcf19da8000, 4096, PROT_READ) = 0
mprotect(0x7fcf19fc0000, 4096, PROT_READ) = 0
mprotect(0x7fcf1a3f8000, 4096, PROT_READ) = 0
munmap(0x7fcf1a3dc000, 103274) = 0
set_tid_address(0x7fcf1a3d99d0) = 2483
set_robust_list(0x7fcf1a3d99e0, 0x18) = 0
futex(0x7fffd6bb89fc, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fffd6bb89fc, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME,
1, NULL, 7fcf1a3d9700) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigaction(SIGRTMIN, {0x7fcf19daf860, [], SA_RESTORER|SA_SIGINFO,
0x7fcf19db8f60}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x7fcf19daf8f0, [],
SA_RESTORER|SA_RESTART|SA_SIGINFO, 0x7fcf19db8f60}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
shmget(0xcafe, 88, 0666) = 2883607
shmat(2883607, 0, 0) = ?
statfs("/dev/shm", {f_type=0x1021994, f_bsize=4096, f_blocks=127182,
f_bfree=127181, f_bavail=127181, f_files=127182, f_ffree=127179,
f_fsid={0, 0}, f_namelen=255, f_frsize=4096}) = 0
futex(0x7fcf19fc52bc, FUTEX_WAKE_PRIVATE, 2147483647) = 0
open("/dev/shm/sem.emcsem1", O_RDWR|O_NOFOLLOW) = 3
fstat(3, {st_mode=S_IFREG|0755, st_size=32, ...}) = 0
brk(0) = 0xc9f000
brk(0xcc0000) = 0xcc0000
mmap(NULL, 32, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = 0x7fcf1a3f4000
close(3) = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0x7fcf1a3f3000
write(1, "Semaphore value is 0\n", 21Semaphore value is 0
) = 21
write(1, "Waiting one second, then until s"..., 55Waiting one second,
then until semaphore gets released
) = 55
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7fffd6bb8860) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++
Segmenteringsfel
And a small guess ... I'm running 64 bit ? ...
I don't know if 64 bit make problems in the EMC world. But I saw this in the output you sent: "Error while shmget". It seems like shmget fails for some reason, but the strace seems normal. And I saw that I forgot the exit statement in the error handler, this is probably the reason why it "Segmenteringsfels" later.
@@ -93,6 +93,7 @@ int main()
id = shmget(key, size, SHM_PERMISSIONS);
if (id == -1) {
printf("Error while shmget\n");
+ exit(-1);
}
Can you maybe try to remove the two shm-memories with ipcrm?
I have not had time to look to much at the code, since I have been ill this week, but It seems to run. I have mostly been busy trying to get an USB driver running for my hardware, sorry but limited time. I do believe that shm_interface_test ran a couple of times .... Tell me if I can run any test, but at the moment I am actually more concearned about RT-Preempt EMC :-D ... which is a reason to be really happy.
Do you like to tell me what you intend to do with an RT_Preempted EMC? Doing this seems kind of "unusal" :) .
Have you tried the mailinglist for rt-preempt about the timing ? it's on http://osadl.org/ , or lkml.org ... I knot the hpet timers have undergone some work.
Unfortunately, I had no time yet to look at the timing issues. It works quite well on some machines here, on some others there are few problems. Latencies around 100us are probably bad, but it's currently enough for our purposes.
Regards Michael
/ regards, Lars Segerlund. 2011/6/19 Michael Abel<michael.a...@isw.uni-stuttgart.de>:Hi Lars, I walked a bit trough the code and tried some things out. There is already cleanup code to avoid this problem, but the cleanup works only when emc is started as root. It seems just like a problem with permissions. I recommend to start emc as root to avoid the problems. In case of problems it's also possible to remove the shm by hand with these commands: ipcrm -M 0x48414c32 #(hal shm) ipcrm -M 0x0000cafe #(shm interface) Can you please tell me more about the segfaulting shm_tester? I have no problems with this program here... Thanks! regards Michael
---------------------------------------------------------------- Dipl.-Ing. Michael Abel Graduate School advanced Manufacturing Engineering GSaME - Universität Stuttgart Institut für Steuerungstechnik der Werkzeugmaschinen und Fertigungseinrichtungen ISW - Universität Stuttgart Seidenstr. 36 70174 Stuttgart Tel.: ++49 (0) 711 685-82532 Fax : ++49 (0) 711 685-82808 michael.a...@isw.uni-stuttgart.de michael.a...@gsame.uni-stuttgart.de www.isw.uni-stuttgart.de www.gsame.uni-stuttgart.de
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