SETUP(2) Linux Programmer's Manual SETUP(2)

setup - setup devices and filesystems, mount root filesystem

#include <unistd.h>
int setup(void);

setup() is called once from within linux/init/main.c. It calls initialization functions for devices and filesystems configured into the kernel and then mounts the root filesystem.
No user process may call setup(). Any user process, even a process with superuser permission, will receive EPERM.

setup() always returns -1 for a user process.

Always, for a user process.

Since Linux 2.1.121, no such function exists anymore.

This function is Linux-specific, and should not be used in programs intended to be portable, or indeed in any programs at all.

The calling sequence varied: at some times setup() has had a single argument void *BIOS and at other times a single argument int magic.
2008-12-03 Linux