Re: Error message not relevant
On Wed, Nov 20, 2013 at 11:43 PM, Nav Kamal wrote: > Am learning to write LKMs and wrote this program : > > #include > #include > 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 ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Error message not relevant
* Nav Kamal wrote (on 2013-11-20 16:43:26 +): > Am learning to write LKMs and wrote this program : > > #include > #include > 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 : What was the exact value? Must be you returned -1, as an example try to pass some other lower negative numbers. It converts to error string using err or perror. So you get that permission denied for the value you passed. > > "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 ? Santosh -- When you really want something (and take the first steps in that direction), the entire universe will conspire to fulfill your desire. -- P. Coelho ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Error message not relevant
Am learning to write LKMs and wrote this program : #include #include 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 ? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies