What happens when a linux system boots?

1. Press the Power button
2. BIOS / UEFI => Powers up peripherals
3. BIOS/ UEFI => Runs the POST (Power On Self Test)
4. BIOS/ UEFI => Finds and loads the boot loader (like GRUB2, LILO, etc.)
   • Boot loader is located in the MBR for BIOS
   • It is located in the separate .efi partition for UEFI
5. The boot loader locates the OS in the memory
6. The boot loader loads the OS kernel and hands control over to it
7. First the kernel decompresses itself
8. Then it check all the hardware and loads device drivers
9. The kernel then starts the init process - Systemd in linux
10. The init process starts all the necessary background processes and services

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Related §

• What happens at init

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Refs §

1. https://www.youtube.com/watch?v=XpFsMB6FoOs