You can add the package definition to your operating system configuration file like so, before the operating-system declaration: (use-modules (gnu packages bootloaders)) (define u-boot-my-board (make-u-boot-package " Myboard " " arm-linux-gnueabihf " )) (operating-system [...]) Then, you need to define the bootloader. A bootloader is a structure that has a name, a package, an installer, a configuration file and a configuration file generator.