whatis boot-process
Boot Process
Also known as: Linux boot sequence
The sequence from power-on to login: firmware (UEFI/BIOS), bootloader, kernel, initramfs, init system, then services and login.
How Does the Linux Boot Process Work?
Firmware initializes hardware and loads a bootloader from disk. The bootloader loads the kernel and initramfs into memory. The kernel sets up hardware and memory, then runs the initramfs, which finds and mounts the real root filesystem (unlocking encryption if needed).
Finally the kernel starts PID 1, usually systemd, which brings up services and a login prompt. systemd-analyze blame shows which units slow the process down.
Example
systemd-analyze
systemd-analyze blame | headLearn more about Boot Process
- Linux Boot Process Explained From pressing the power button to a login prompt, a Linux system goes through a precise sequence of steps. Understanding each stage -- firmware, bootloader, kernel, initrd, and systemd -- demystifies boot failures and makes the system less of a black box.
- BIOS vs UEFI: What's the Difference? BIOS and UEFI are the firmware interfaces that initialize hardware before the OS loads. Understanding the difference matters for installing Linux, setting up dual boot, and configuring Secure Boot. This guide explains both clearly.
- The /boot Directory Explained: vmlinuz, initramfs and the EFI Partition What each file in /boot does, why /boot/efi is a different filesystem with different rules, why the partition fills up and takes your next kernel update with it, and what is safe to delete when it does.