Linux Boot-up Sequence

The Linux boot-up sequence basically follows six steps to complete the boot-up sequence. Each step is responsible for (depends on) the next.

Basic Input Output System (BIOS)

• Searches and executes the boot loader program from the MBR.
• It is like an abstraction layer between the hardware and the software.

Master Boot Record (MBR)

• It is located in the first sector of the boot disk. It takes around.
• Some boot loaders are GRUB, LILO or Linux Loader.

KERNEL

• Located on a disk partition.
• It mounts the root file system.
• It contains drivers for hardware support.
• It executes the Init program.

INIT PROCESS

The INIT process is responsible for the run-levels:

1. Halt
2. Single user mode
3. Multiuser mode without NFS
4. Unused, For research purpose
5. Full multiuser with Graphical mod
   
6. Reboot