BOOTUP(7) bootup BOOTUP(7) - . ( systemd-boot(7) GRUB[1]) . ( ). EFI . () . "initramfs" -- CPIO tmpfs. (ramdisk) "initrd" . initrd/initramfs . systemd(1) initrd . initrd ( systemd(1)) . ( ) () exitrd. exitrd tmpfs . . boot(7). . systemd(1) . ( systemd.target(5) .) . systemd default.target ( ). default.target graphical.target multi-user.target . systemd.special(7). . . . cryptsetup-pre.target veritysetup-pre.target | (various low-level v API VFS mounts: (various cryptsetup/veritysetup devices...) mqueue, configfs, | | debugfs, ...) v | | cryptsetup.target | | (various swap | | remote-fs-pre.target | devices...) | | | | | | | | | v | v local-fs-pre.target | | | (network file systems) | swap.target | | v v | | | v | remote-cryptsetup.target | | | (various low-level (various mounts and | remote-veritysetup.target | | | services: udevd, fsck services...) | | | | | tmpfiles, random | | | remote-fs.target | | seed, sysctl, ...) v | | | | | | local-fs.target | | _____________/ | | | | | |/ \____|______|_______________ ______|___________/ | \ / | v | sysinit.target | | | ______________________/|\_____________________ | / | | | \ | | | | | | | v v | v | | (various (various | (various | | timers...) paths...) | sockets...) | | | | | | | | v v | v | | timers.target paths.target | sockets.target | | | | | | v | v \_______ | _____/ rescue.service | \|/ | | v v | basic.target rescue.target | | | ________v____________________ | / | \ | | | | | v v v | display- (various system (various system | manager.service services services) | | required for | | | graphical UIs) v v | | multi-user.target emergency.service | | | | \_____________ | _____________/ v \|/ emergency.target v graphical.target . systemd.unit= ( systemd(1)) default.target . timers.target basic.target . . user@uid.service systemd -- . default.target. . default.target. graphical-session.target . ( ) . (various (various (various timers...) paths...) sockets...) (sound devices) | | | | v v v v timers.target paths.target sockets.target sound.target | | | \______________ _|_________________/ (bluetooth devices) \ / | V v basic.target bluetooth.target | __________/ \_______ (smartcard devices) / \ | | | v | v smartcard.target v graphical-session-pre.target (various user services) | (printers) | v | | (services for the graphical session) v | | printer.target v v default.target graphical-session.target INITRD Systemd initrd . initrd /etc/initrd-release. initrd initrd.target. basic.target. systemd initrd.target. . systemd-hibernate-resume.service local-fs-pre.target . initrd-root-device.target. /sysroot sysroot.mount initrd-root-fs.target. initrd-parse-etc.service /sysroot/etc/fstab /usr/ x-initrd.mount. /sysroot initrd-fs.target. initrd-cleanup.service initrd-switch-root.target . initrd-switch-root.service /sysroot. : (beginning identical to above) : v basic.target | emergency.service ______________________/| | / | v | initrd-root-device.target emergency.target | | | v | sysroot.mount | | | v | initrd-root-fs.target | | | v v initrd-parse-etc.service (custom initrd | services...) v | (sysroot-usr.mount and | various mounts marked | with fstab option | x-initrd.mount...) | | | v | initrd-fs.target \______________________ | \| v initrd.target | v initrd-cleanup.service isolates to initrd-switch-root.target | v ______________________/| / v | initrd-udevadm-cleanup-db.service v | (custom initrd | services...) | \______________________ | \| v initrd-switch-root.target | v initrd-switch-root.service | v Transition to Host OS systemd : (conflicts with (conflicts with all system all file system services) mounts, swaps, | cryptsetup/ | veritysetup | devices, ...) | | v v shutdown.target umount.target | | \_______ ______/ \ / v (various low-level services) | v final.target | ___________________________/ \_________________________________ / | | | \ | | | | | v | | | | systemd-reboot.service | | | | | v | | | | systemd-poweroff.service | | | v | v | | reboot.target | systemd-halt.service | | v | v | poweroff.target | systemd-kexec.service | v | | halt.target | systemd-soft-reboot.service v | kexec.target | v soft-reboot.target . systemd-halt.service(8) systemd-reboot.service systemd-poweroff.service systemd-kexec.service (PID 1) ( systemd-shutdown) . . EXITRD "exitrd" initrd. /run/initramfs/shutdown /run/initramfs/ /shutdown. tmpfs /run/ . systemd(1), boot(7), systemd.special(7), systemd.target(5), systemd-halt.service(8), systemd-soft-reboot.service(8) 1. GRUB https://www.gnu.org/software/grub/ 3 . . : . systemd 260.2 BOOTUP(7)