setup man page
setup — setup devices and filesystems, mount root filesystem
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.
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