Restore kernel on Arch Linux

Published on: 2025-05-01

Yesterday I had the heart-attack-inducing experience of an unbootable system after my usual pacman -Syu, which most of the time works out just fine. Some of the time something breaks, but nothing as serious as this: every trace of the Linux kernel had vanished from my /boot drive, leaving my beloved Thinkpad with no brains to do anything but drop back to the BIOS setup. After much fiddling and cursing I finally managed to get the system up and running again, using a relatively recent USB installation medium I had lying around after reinstallling Arch on another laptop.

I am writing the steps down here, so that I will remember this in the future if something similar should happen again. And, who know, maybe it's useful for others as well…

• Insert the installation media before booting and hit F12 when starting up to get the boot menu.
• Connect the laptop to an ethernet cable for internet connection. iwctl is available as well for wireless connection, but it's much quicker to just cable up.
• mkdir /mnt. The leading / is important!
• Decrypt the encrypted main partition: cryptsetup luksOpen /dev/nvme0n1p2 crypt-partition
• mount /dev/mapper/main_group-root /mnt. Note that main_group-root is the name of the partition, not crypt-partition!
• mount /dev/nvme0n1p1 /mnt/boot The boot directory probably exists already, as we're recovering an existing system, not installing a new one.
• arch-chroot /mnt
• pacman -S linux
• reboot

And that's it! After this my system was back up again, as if nothing had ever happened.