Hi,
Am 2012-05-23 09:01, schrieb 석현철:
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.
The error message has nothing to do with the header, as it is an error in the link phase, where the symbols of the libpthread can not be resolved.
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.”
Yes, you need to include this line in your Makefile and for me this leads to the program linking correctly. Are you sure you included it in server/src/Makefile and not somewhere else? Can you show us your Makefile and the Output of
make V=1
to see the compiler and linker commands invoked?
Actually, I tried it, but I couldn’t solve the problem.
How can I use the pthread? Please, Help me!!
Thank you!
Hyunchul Seok
Kind regards,
Marcus
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 threadn", 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;
}