New system call and User space header file

["Sachin Gaikwad" <sachin.kernel@xxxxxxxxx>]

Hi all,

 

If I am adding a new system call sys_myroutine into the kernel then why is it necessary to have header file in user space like this -

 

#include <unistd.h>

 

_syscall2(int, myroutine, int arg1, int, arg2);

 

What does it do when a user program calls this system call ? Can somebody explain this to me ?

 

Thanks in advance,

Sachin