Question

I write a module,and want add it to kernel.It will print a world when i insmod the module.but it will not…

the module as:

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

static int __init hello_init()
{
    printk(KERN_EMERG"Hello World!\n");
    return 0;
}

static void __exit hello_exit()
{
    printk("<6>hello exit\n");
}

module_init(hello_init);
module_exit(hello_exit);

why the “Hello World!\n” dose not print when i load the module??
Are there some one meet the question? thinks for your help….

Answer 1

Since you didn’t get a compile/linking error and insmod/modprobe didn’t complain about missing symbols, there are two reasons why this can happen:

1. Someone defined a macro printk()
2. You looked in the wrong place. The text will be printed to the syslog. To see that, use dmesg | tail