Thuc notes © 2022

Linux Boot Process

Part of series osdev |

General steps:

  • Power on.
  • Bootloader.
  • Kernel load.
  • Run level.



  • Choose OS.
  • Choose kernel.
  • Load and execute kernel and initrd.

Kernel load

  • initrd loads a temporary root file system into memory until real file system is mounted.
  • Start load kernel and real file system.
  • Mount real root file system.
  • Execute /sbin/init as 1st program, can be systemd or SysV init.

Run level

  • Mount file system.
  • Decide what run-level will be run.
  • Run scripts from /etc/rc[0-6S].d directory bases on run-level.
  • /etc/rc[0-6S].d/S…. : is run when starting.
  • /etc/rc[0-6S].d/K…. : is run when stopping.

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Tags: linux | firmware | boot |