add a new system call

From: mojtaba
Date: Tue Jan 12 2010 - 08:54:17 EST

[please cc kernelppc@xxxxxxxxx in your replies]

Dear all,

I need to add a new system call to the linux kernel.

These are the linux information:
Linux ubuntu-desktop #5 SMP Mon Jan 11 16:56:27 CET 2010 i686

I am working on kernel 2.6.32.

These are all the changes I did:

1- adding " .long sys_mycall" to the end of

2- adding
#define __NR_mycall 242
__SYSCALL(__NR_mycall, sys_mycall)
#undef __NR_syscalls
#define __NR_syscalls 243
to the "include/asm-generic/unistd.h"

3- adding
asmlinkage long sys_mycall(char * fname, void * params);
to the end of "/include/linux/syscalls.h"

4-modifying the linux Makefile
core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/ mycall/

5- adding mycall folder to kernel source and mycall.c and the
corresponding Makefile in it:
#include <linux/kernel.h>
#include <linux/syscalls.h>
SYSCALL_DEFINE2(mycall, char __user *, fname,void __user *,params)
printk("I am here !!";
return 10;
Now after building and installing the new kernel, I want to test the
system call with this code:

#include <errno.h>
#include <sys/syscall.h>

#define __NR_mycall 242

long mycall(char * fname, void * params )
return syscall(__NR_mycall, fname, params);

int main(void)
int tmp=10;
int er=0;
char * chp= (char *) &tmp;
void * vp= (void *) &tmp;
printf("%d\n", er=mycall(chp,vp));
if( er < 0 ) {
printf( "Error: %d, %s\n", errno, strerror( errno ) );
Unfortunately, the code prints this:
Error: 3, No such process

And I have no idea what the problem is!

Is there any body who can help me?

Thank you and best regards,
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