Linux Boot Process

Learn the 6-stage boot sequence, then prove you can troubleshoot when it breaks.

THE DECISION PATTERN

"Work from the bottom up: power → firmware → bootloader → kernel → initramfs → systemd → services. At each layer, ask two questions:"

1. How far did it get?

Identify the phase — each phase has distinct symptoms.

2. What can I still reach?

Determines which tools are available for diagnosis.

Capture evidence before rebooting. SEL logs, console output, panic traces — document first, then recover.