Hi I believe that every system call should have an entry in /usr/src/linux/arch/i386/kernel/entry.S. But, when I searched for __NR_shmget , to my surprise there is none related to shared memory or semaphore . So, I am wondering how are,the system calls related to IPC gets executed.. Do any one have an idea of how it is?? P.S: but, I did see an entry like __NR_ipc. I don't know how this would help. thanks! Charumathi. You Can If U think U Can _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/