Hi. Hackers I’m trying to use pthread in an application which runs on L4. I modified “main.c” in Hello application, including “#include <pthread.h>”. And when I compiled L4Re, I got error messages: main.o: In function `main': /root/l4re-core-2011081207/src/l4/pkg/hello/server/src/main.c:39: undefined reference to `pthread_create' /root/l4re-core-2011081207/src/l4/pkg/hello/server/src/main.c:44: undefined reference to `pthread_join' make[5]: *** [hello] Error 1 I think this is because it cannot fine pthread.h header file. But I don’t know how to fix it. When I looked up previous lists, I could find one thread related to pthread in 2011 list. (the thread title is “Silly Pthread Issues”) I think that it is the same problem, but the reply is only one. Said “Add REQUIRES_LIBS = libpthread to the Makefile.” Actually, I tried it, but I couldn’t solve the problem. How can I use the pthread? Please, Help me!! Thank you! Hyunchul Seok The modified code is below: #include <stdio.h> #include <unistd.h> //#include <pthread-l4.h> #include <pthread.h> void *process_test(void *arg) { int i = (int)arg; int j; for (;;) { for (j = 0; j < i; j++) { printf(" "); } printf("%d thread\n", i); sleep(i); } } int main(void) { pthread_t threads[10]; int status[10]; int i; for (i = 0; i < 3; i++) { pthread_create(&threads[i], NULL, process_test, (void *)i); puts("New thread creation!"); } for (i = 0; i < 3; i++) { pthread_join(threads[i], (void **)&status[i]); } return 0; }