Unimplemented system call

[valdis.kletnieks at vt.edu]

On Tue, 05 Mar 2019 19:08:20 -0500, Umair Khan said:

> I was just roaming around the linux source code when I stumbled upon
> this line - https://github.com/torvalds/linux/blob/master/include/linux/syscalls.h#L1200
>
> May I know what is the use of this system call?

/*
 * Not a real system call, but a placeholder for syscalls which are
 * not implemented -- see kernel/sys_ni.c
 */
asmlinkage long sys_ni_syscall(void);

Well, did you go look at kernel/sys_ni.c like it told you to?  Because if you
bothered reading the first 2 dozen lines of that file, you would find:

/*
 * Non-implemented system calls get redirected here.
 */
asmlinkage long sys_ni_syscall(void)
{
        return -ENOSYS;
}

Are there any remining questions?