Cucumber Linux Wiki

Cucumber Linux uses efibootmgr (https://github.com/vathpela/efibootmgr) to configure the UEFI firmware. Efibootmgr will not work straight out of the box though. This is due to the face the the efivars partition (/sys/firmware/efi/efivars) is not mounted by default on Cucumber Linux. In order to use efibootmgr to edit your boot process, you must first run the following:

modprobe efivarfs
mount -t efivarfs efivarfs /sys/firmware/efi/efivarfs

Have fun setting up UEFI, and don't brick your motherboard.