A VBT file is required for building.
FIRMWARE_OPEN_VBT=../lemp9.vbt make
The qemu target will use the target directory as a pseudo-drive so the
driver files can be viewed.
FIRMWARE_OPEN_VBT=../lemp9.vbt make qemu
In QEMU, the driver can be loaded using the UEFI Shell load command.
Shell> fs0:
FS0:\> load release\system76_gop_policy.efi