Tools such as efibootmgr rely on the deprecated /sys/firmware/efi/vars API as well as on the new /sys/firmware/efi/efivars API. The latter needs to be mounted. Reported by Keyhenge here: https://lists.gnu.org/archive/html/bug-guix/2020-04/msg00274.html Here is the efivarfs documentation: https://www.kernel.org/doc/Documentation/filesystems/efivarfs.txt. * gnu/system/file-systems.scm (%efivars-file-system): New exported variable, (%base-file-systems): add it. * gnu/system/install.scm (%efivars-file-system): Add it. Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>