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Unified Extensible Firmware Interface

Is a set of specification & Software platform that is used to boot and interface with an Operating System

Secure Boot

  • Is a method to check whether a bootloader is digitally signed.
  • Boot Order Lock also lock book order and shim selection

USB Key preparation

  • In Rufus, prepare a non-bootable MBR FAT32 key
  • Then copy the required files, for example from Clonezilla

UEFI Shell

  • Works similarly to a bash shell
  • The bootloader is searching for /EFI/BOOT/bootx64.efi by default ^333cb0


  • map to show the mapping table
  • cd /EFI/BOOT/ to browse to path
  • bcfg boot add 1 bootx64.efi "OSname" to add an entry
    • 1 being the priority

Recover from a bad boot

  • You are greeted with the UEFI Shell, so try to find the loader:
  • The mapping table will give you all devices that EFI see, like FS0: or HD0b:
  • Browse to the bootloader
    • FS0:
    • cd EFI\debian
    • grubx64.efi