diskimage-builder/elements/vm/README.rst

vm

Sets up a partitioned disk (rather than building just one filesystem with no partition table).

By default the disk will have grub[2]-install run on it. In case GRUB2 is not available in the system, a fallback to Extlinux will happen. It's also possible to enforce the use of Extlinux by exporting a DIB_EXTLINUX variable to the environment.