I recently loaded the setup defaults on my ThinkPad after trying to diagnose a
boot problem and this cleared the UEFI boot entries leaving me unable to boot
my installed OS. In this article, I'll show you how to recreate a new boot
entry using efibootmgr.
You'll need a live OS to boot from that has efibootmgr. You might be able to
use the Debian netinst rescue mode, but I would recommend the full
live install images. I used Tails, a Debian-based live OS focused on
privacy, because it's what I had on hand. If you do use Tails, make to
enable the administration password at the Tails Greeter.
Whatever you choose, boot into it and get yourself to a root prompt.
Identify the device name for your system partition. In my case, my EFI System
partition is sda1, which is always a FAT filesystem and is usually the first
partition on a disk.
root@amnesia:~# lsblk -o NAME,FSTYPE,MODEL,SIZE
NAME FSTYPE MODEL SIZE
sda SB2 223.6G
├─sda1 vfat 512M
├─sda2 ext2 244M
└─sda3 crypto_LUKS 222.9G
└─sda3_crypt LVM2_member 222.8G
├─thinkpad--vg-root ext4 28G
├─thinkpad--vg-swap_1 swap 11.9G
└─thinkpad--vg-home ext4 183G
sdb USB_2.0_FD 7.5G
├─sdb1 vfat 4G
└─sdb2 crypto_LUKS 3.5G
I recommend mounting the EFI system partition to check you have the right disk and also to verify the path to the UEFI binary we'll need next. Unmount when you're done.
root@amnesia:~# mount /dev/sda1 /mnt
root@amnesia:~# find /mnt
/mnt
/mnt/EFI
/mnt/EFI/debian
/mnt/EFI/debian/shimx64.efi
/mnt/EFI/debian/grubx64.efi
/mnt/EFI/debian/mmx64.efi
/mnt/EFI/debian/fbx64.efi
/mnt/EFI/debian/BOOTX64.CSV
/mnt/EFI/debian/grub.cfg
/mnt/EFI/debian/grub.efi
/mnt/EFI/debian/grubia32.efi
Now that you've identified the correct disk, use efibootmgr to create a new
entry. --disk is the disk of the system partition, not the partition
itself! --part is the partition number, starting at 1. --loader is the
path to the UEFI binary. You will need to use shimx64.efi instead of
grubx64.efi if you're using SecureBoot. You must use
backslashes as the path separator.
root@amnesia:~# efibootmgr --verbose --create --disk /dev/sda --part 1 --loader "\efi\debian\grubx64.efi" --label "Debian"
BootCurrent: 0008
Timeout: 2 seconds
BootOrder: 0012,0000,0001,0002,0003,0007,0008,0009,000A,000B,000C,000D
Boot0000 Setup FvFile(721c8b66-426c-4e86-8e99-3457c46ab0b9)
Boot0001 Boot Menu FvFile(126a762d-5758-4fca-8531-201a7f57f850)
Boot0002 Diagnostic Splash Screen FvFile(a7d8d9a6-6ab0-4aeb-ad9d-163e59a7a380)
...
Boot0012* Debian HD(1,GPT,3b9ed62c-c28d-4866-842e-29c9bc7b0ac7,0x800,0x100000)/File(\efi\debian\grubx64.efi)
Assuming everything went OK, efibootmgr will list all the entries (which I
trimmed here) and your new one should be at the bottom. Confirm everything
looks correct and reboot. Fingers crossed!