Linux

Starting Linux

Pre-Loader

• Boot ROM
• Secondary Program Loader for U-Boot
• Commom Firmware Environment (CFE)
• Bootloader
  • BIOS: GRUB, Limine
  • UEFI: GRUB, Limine, rEFInd, systemd-boot

Bootloader

https://wiki.cachyos.org/installation/boot_managers/

UEFI (Unified Extensible Firmware Interface) is a specification: https://uefi.org/

During the bootloader, basic initialization of the system:

• RAM
• Serial port
• Hardware detection
  • ARM Tags (ATAG) - old
  • Device tree
• Loading and calling the image

Device Tree is made of two format:

• Device Tree Source, DTS
• Device Tree Blob, DTB or Flattened Devicetree

Examples of bootloader:

• Das U-Boot (embedded)
• GRUB, systemd-boot
• Windows Boot Manager

Starting the image

• r0: 0
• r1: platform ID
• r2: ATAG or device tree (known by the magic 0xd00dfeed)