#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

static int test_init(void)
{
    printk("Hello World\n");
    return 0;
}

static int test_exit(void)
{
    printk("Bye Bye\n");
}

module_init(test_init);
module_exit(test_exit);
MODULE_LICENSE("TEST");

root@nocode:~/ca# insmod test.ko
root@nocode:~/ca# cat /var/log/messages
....
Jan 13 10:02:59 nocode kernel: [59541.228159] Hello World
root@nocode:~/ca#
root@nocode:~/ca# rmmod test
root@nocode:~/ca# cat /var/log/messages
....
Jan 13 10:04:30 nocode kernel: [59631.677166] Bye Bye
root@nocode:~/ca#