On 2013-02-11 16:10:38 (+0530), sunil <sunil.slvphsn@gmail.com> wrote:

-------------output---------------------------- sunil@ubuntu:~/test/drive$ sudo insmod ./helloworld.ko insmod: error inserting './helloworld.ko': -1 File exists

This means you've already loaded the module. Try 'sudo rmmod helloworld' to unload it first. This should generate the 'Goodbye, cruel world' dmesg trace. After that you can load the module again. Regards, Kristof