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== Reboot into BIOS ==

{{{#!highlight sh numbers=off
sudo systemctl reboot --firmware-setup
}}}

[[https://superuser.com/a/1083166/20815|Ref]]
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If using a chroot to reinstall entries, first setup various bind mounts outside the chroot:
{{{#!bash		 If using a chroot to reinstall entries, first setup various bind mounts from outside the chroot into the chroot:

{{{#!highlight sh

Notes related to Extensible Firmware Interface (EFI).

Reboot into BIOS

sudo systemctl reboot --firmware-setup

Ref

Repair for Linux

To reinstall UEFI entries, check what's installed with efibootmgr --verbose which will list all boot entries, and the default. If the entry for the OS is missing (usually "debian" or "ubuntu"), the entry may need to be re-added. Rather than manipulating EFI variables, it's easiest to reinstall grub which ensures all files/etc are in the right place.

If using a chroot to reinstall entries, first setup various bind mounts from outside the chroot into the chroot: 

   1 CHROOT_ROOT=/mnt
   2 # mount --bind /dev/ $CHROOT_ROOT/dev
   3 # mount --bind /dev/pts $CHROOT_ROOT/dev/pts
   4 # OR
   5 mount --rbind /dev/ $CHROOT_ROOT/dev
   6 mount --bind /sys $CHROOT_ROOT/sys
   7 mount --bind /proc $CHROOT_ROOT/proc
   8 mount --rbind /run $CHROOT_ROOT/run
   9 
  10 modprobe efivarfs
  11 mount -o bind /sys/firmware/efi $CHROOT_ROOT/sys/firmware/efi

Also ensure the EFI partition is mounted at the correct location (e.g. usually /boot/efi).

After entering the chroot, reinstall grub with: 

grub-install --target=x86_64-efi --efi-directory=/boot/efi

Afterwards, double-check the boot entry shows up with efibootmgr.

CategoryCheatSheet

SamatsWiki: CheatSheet/EFI (last edited 2025-12-03 04:39:13 by SamatJain)