busybox/klibc-utils/run-init.c

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/*
* run-init implementation for busybox
*
* Copyright (c) 2017 Denys Vlasenko <vda.linux@gmail.com>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config RUN_INIT
//config: bool "run-init (7.7 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: The run-init utility is used from initramfs to select a new
//config: root device. Under initramfs, you have to use this instead of
//config: pivot_root.
//config:
//config: Booting with initramfs extracts a gzipped cpio archive into rootfs
//config: (which is a variant of ramfs/tmpfs). Because rootfs can't be moved
//config: or unmounted, pivot_root will not work from initramfs. Instead,
//config: run-init deletes everything out of rootfs (including itself),
//config: does a mount --move that overmounts rootfs with the new root, and
//config: then execs the specified init program.
//config:
//config: util-linux has a similar tool, switch-root.
//config: run-init differs by also having a "-d CAPS_TO_DROP" option.
/* applet and kbuild hooks are in switch_root.c */