Error message not relevant

[Mulyadi Santosa]

On Wed, Nov 20, 2013 at 11:43 PM, Nav Kamal <navkamal90 at gmail.com> wrote:
> Am learning to write LKMs and wrote this program :
>
> #include<linux/init.h>
> #include<linux/module.h>
> static int module_entry(void){
>         printk(KERN_ALERT "Hello World !!\n");
>         return 0;
> }
> static void exit_module(void){
>         printk(KERN_ALERT "Bye World .... \n");
> }
> module_init(module_entry);
> module_exit(exit_module);
>
> In this program if I change return value of function module_entry from 0 to
> something negative, the module fails to load. The error message is :
>
> "insmod: ERROR: could not insert module test.ko: Operation not permitted"
>
> Failing to load module with negative return value is understandable but I
> can't understand why it says "Operation not permitted". Its not about user
> permissions, its about return value. Can somebody please guide me about this
> ?

AFAIK, insmod/modprobe translate any errors during module load as "not
permitted". This doesn't mean you can not read the .ko files, it just
means you can't load it.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com