setup is called once from within linux/init/main.c. It calls
initialization functions for devices and file systems configured into the
kernel and then mounts the root file system.
No user process may call setup. Any user process, even a process with
super-user permission, will receive EPERM.
This function is Linux specific, and should not be used in programs intended to
be portable, or indeed in any programs at all. Since Linux 2.1.121, no such
function exists anymore. The calling sequence varied: it has had a single
parameter void * BIOS and at other times a single parameter int