"FATAL: Module not found error" using modprobe

Question

Hello,

i have an problem with modprobe command...i compiled the hello world module and inserted using "insmod" command...and its working..when i see "lsmod" its in that list...but when i insert this module using "modprobe" i am getting the FATAL error....that is

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

Here is the code of the module

#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

Try insmod instead of modprobe. Modprobe looks in the module directory /lib/modules/uname -r for all the modules and other files

Answer 2

The reason is that modprobe looks /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.

Answer 3

The best thing is to actually use the kernel makefile to install the module:

Here is are snippets to add to your Makefile

around the top add:

PWD=$(shell pwd)
VER=$(shell uname -r)
KERNEL_BUILD=/lib/modules/$(VER)/build
# Later if you want to package the module binary you can provide an INSTALL_ROOT
# INSTALL_ROOT=/tmp/install-root

around the end add:

install:
        $(MAKE) -C $(KERNEL_BUILD) M=$(PWD) \
           INSTALL_MOD_PATH=$(INSTALL_ROOT) modules_install

and then you can issue

    sudo make install

this will put it either in /lib/modules/$(uname -r)/extra/

or /lib/modules/$(uname -r)/misc/

and run depmod appropriately