Focal armhf and arm64 builds fail with semop: function not implemented: #36
Comments
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Edit: Oops, disregard, that's waaaay too old. |
This one was the first I see failing: https://build.osrfoundation.org/view/All/job/ign-math6-debbuilder/396/console |
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To reproduce locally: Also, running |
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
int main() {
struct sembuf sops[1];
int semid = semget(12345, 1, IPC_CREAT|0600);
sops[0].sem_num = 0;
sops[0].sem_op = -1;
sops[0].sem_flg = SEM_UNDO;
if (semop(semid, sops, 1) == -1) {
perror("semop");
return 1;
}
return 0;
}Expected behavior: it should block forever because "If sem_op is less than zero [...] semncnt (the counter of threads waiting for this semaphore's value to increase) is incremented by one and the thread sleeps" Actual behavior: |
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Running It looks like the syscall returning
Since
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Minimal example calling #define _GNU_SOURCE // Compiler warns semtimedop is implicitly declared without this
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
int main() {
struct sembuf sops[1];
int semid = semget(12345, 1, IPC_CREAT|0600);
sops[0].sem_num = 0;
sops[0].sem_op = -1;
sops[0].sem_flg = SEM_UNDO;
if (semtimedop(semid, sops, 1, NULL) == -1) {
perror("semtimedop");
return 1;
}
return 0;
}root@c9b5a3fddeba:/tmp# gcc semop.c
root@c9b5a3fddeba:/tmp# ./a.out
semtimedop: Function not implemented |
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Adding a sleep to the above program and running sleep first code#define _GNU_SOURCE // Compiler warns semtimedop is implicitly declared without this
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <unistd.h>
int main() {
sleep(15);
struct sembuf sops[1];
int semid = semget(12345, 1, IPC_CREAT|0600);
sops[0].sem_num = 0;
sops[0].sem_op = -1;
sops[0].sem_flg = SEM_UNDO;
if (semtimedop(semid, sops, 1, NULL) == -1) {
perror("semtimedop");
return 1;
}
return 0;
} |
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I cam reproduce the issue outside of a docker container by building
Output: If I build qemu Then in the |
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Getting the example out of the docker container allowed me to run gdb with It looks like the root cause is I think what happened is we were using |
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Nice analysis, @sloretz . The "correct" way to fix this does seem to be to implement However, we may be able to do a short-term workaround as well. If we do an LD_PRELOAD inside of the qemu userland, and redirect the implementation of |
It looks like that works! Now to add it to the Dockerfile #define _GNU_SOURCE
#include <unistd.h>
#include <asm/unistd.h>
#include <sys/syscall.h>
/* glibc 2.31 wraps semop() as a call to semtimedop() with the timespec set to NULL
* qemu 3.1 doesn't support semtimedop(), so this wrapper syscalls the real semop()
*/
int semop(int semid, struct sembuf *sops, unsigned nsops)
{
return syscall(__NR_semop, semid, sops, nsops);
} |
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I'm happy to have found this discussion. I'm using qemu to autobuild packages for Arch Linux ARM. I use qemu 4.2 for my builds which still seems to have this problem: https://travis-ci.com/github/VDR4Arch/vdr4arch/jobs/326884620#L1596 I've filed an upstream bug just to see how the current status is about fixing this directly in qemu: https://bugs.launchpad.net/qemu/+bug/1876568 Edit: Your workaround does fix my issue, so I think it is proven that qemu 4.2 still has the issue. This is the fix I use for my build tool: |
Opening a ticket with notes copied from: #35 . See also @clalancette's comment #35 (comment) . @j-rivero also says similar errors are happening on http://build.osrfoundation.org
The Noetic Focal armhf and arm64 jobs jobs all started failling 2 days ago.
Random Notes
semop()to decrement a semaphoreFunction not implementedis whatperror()prints when a syscall returnsENOSYSENOSYSis not one of the documented error codes forsemop()semop(), though I wasn't able to find a spot where it would returnENOSYSin thestable-3.1branch.osrf/ubuntu_armhf:focalandosrf_ubuntu_arm64:focal, meaning they have exactly the same version of qemu, so that hasn't changed.fakeroot,1.24-1fakeroot-> containerglibc->qemu-> hostglibc->kernelglibcversion2.30-0ubuntu3glibcversion2.31-0ubuntu6The text was updated successfully, but these errors were encountered: