1. You all Must have root access when login to linux if not then do following.  

  

Login as user in linux. Open new terminal and type this command sudo passwd root o enter user passward, o enter new password, o confirm new password, Reboot and select others from list at login time. enter username = root password = you set new password for root above

When you login from root the administrative rights are open for you 2. Download the latest version of the 3.2.9 Linux kernel, I provided a copy at xeon\Spring 2012\OS-Lab also. 3. Uncompress the kernel and place it in /usr/src/.

4. Create a NewFolder In /usr/src/Linux-3.2.9/

5. Create new C file that would contain new system call lets say “myservice.c” in NewFolder. 6. Define your system call in file myservice.c #include //for linking a system call #include //for the printk asmlinkage long sys_myservice (int arg1) { printk(KERN_EMERG “My Service is Running”); return 1; }

7. Create a Makefile and add following code in it in Newfolder. #####Makefile Start##### obj-y += myservice.o #####Makefile End#######

8. In /usr/src/linux-3.2.9/arch/x86/include/asm/unistd_32.h, define an index for system call. #define __NR_myservice 349

9.

Increment the system call count in same file of step 8. #define NR_syscalls 350

10. /usr/src/linux-3.2.9/arch/x86/kernel/syscall_table_32.S, define a pointer to hold a reference to your system call routine. .long sys_myservice

11. In /usr/src/linux-3.2.9/include/linux/syscalls.h contain the declarations for system calls. Add the following line at the end of the file: asmlinkage long sys_myservice (int arg1);

12. Add directory path of the NewFolder to the Makefile (/usr/src/Linux-3.2.9/Makefile) core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/ NewFolder/

13.

Compile Kernel cd usr/src/linux-3.2.9  Enter (make config)  Start compiling to create a compressed kernel image (make)  Start compiling to kernel modules (make modules)  Install kernel modules (make modules_install)  Install kernel (make install)  Reboot System (reboot)

14. Make a new C file for testing in home directory. 15. Enter following code #include #include #include #include

/* for _syscallX macros/related stuff */ /* for struct sysinfo */

#define __NR_my 349 /* No of your system call in unistd list*/ int main() { int error; error=syscall( __NR_my); /* if return -1 syscall fails*/ printf("code error = %d\n ", error); return 0; }

16. 17. 18. 19.

Compile the file using following command on terminal. gcc file.c –o file.exe Run the file using following command. ./file.exe If your system call executes then it will return 1 else -1. Check in var/log/kern.log file for output.