Question

I have a problem with modprobe command… I compiled the hello world module and loaded it with insmod, it works fine and when I do lsmod, I can see it in the output list. But when I insert this module using modprobe I am getting a FATAL error:

root@okapi:/home/ravi# modprobe ./hello.ko 
FATAL: Module ./hello.ko not found.
root@okapi:/home/ravi#

Here is the module code:

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

MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void)
{
        printk(KERN_ALERT "Hello, world\n");
        return 0;
}
static void hello_exit(void)
{
        printk(KERN_ALERT "Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);

and Makefile

obj-m += hello.o

all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Answer 1

The reason is that modprobe looks into /lib/modules/$(uname -r) for the modules and therefore won’t work with local file path. That’s one of differences between modprobe and insmod.