Changed motherboard, how to fix bootloader now?

[waffle8946]

@hexa

Boot into the ISO, mount your partitions and chroot into your system using nixos-enter. Then run

NIXOS_INSTALL_BOOTLOADER=1  /run/current-system/bin/switch-to-configuration boot

That should reinstall the bootloader.

Even though there are no errors when running such a command, that doesn’t work, unfortunately, because it doesn’t set the necessary EFI variables.

There’s a much simpler solution:

1. Boot a live ISO
2. Mount the ESP to say, /boot
3. Run bootctl --path=/boot install
4. Reorder the entries using efibootmgr to put the NixOS-managed bootloader up first
   • Currently this last step doesn’t work, because the version of efibootmgr in nixpkgs is broken, however, this should be fixed if the relevant PR is merged (EDIT: PR’s merged now.)