Linux Boot Sequence

Module 3.10 — From power button to login prompt

Speed:
Stage 1 / 9
HARDWARE
Power On

Power supply sends power-good signal. CPU reset vector jumps to firmware.

Boot Progress

Boot Console
[0.000]CPU reset vector → 0xFFFFFFF0
▊

Stage Details

→PSU stabilizes voltages (3.3V, 5V, 12V)
→CPU reset pin deasserted
→Instruction pointer set to 0xFFFFFFF0
→CPU starts in real mode (16-bit)

System State

CPU ModeReal Mode (16-bit)
Memory0xFFFFFFF0
Duration~0ms

Memory Layout

0x0000-0x03FFIVT
0x7C00-0x7DFFMBR/Boot
0x100000+Kernel
High memoryinitramfs
Userspacesystemd

Key Transitions

→Real Mode (16-bit, 1MB)
→Protected Mode (32-bit, 4GB)
→Long Mode (64-bit, 256TB)
→Ring 0 → Ring 3 (init/systemd)