Target Compatibility

UMF produces four kinds of artifact from a single DSL. The target is inferred from the combination of directives — never declared explicitly. The matrix below shows which directives apply to each target.

	VM	bootc	unikernel	container
FIRMWARE	✓	-	-	-
BOOTLOADER	✓	-	-	-
KERNEL	✓	✓	✓	-
INITRD	✓	✓	-	-
ROOTFS	✓	✓	-	✓
ENTRYPOINT	✓	✓	binary	✓

Legend: ✓ applies — - not applicable to this target — value fixed value required.

Targets at a glance

VM

Bootable disk image with a full boot chain — firmware, bootloader, kernel, initramfs, rootfs, and init system. Suitable for hypervisors (qemu/KVM, VMware, Hyper-V) and bare-metal install.

Boot chain order: FIRMWARE → BOOTLOADER → ROOTFS → KERNEL → INITRD. Init system is selected by ENTRYPOINT (typically systemd).

bootc

Bootable container image — kernel, initramfs, rootfs, init system. Host firmware and bootloader are supplied by the platform (e.g. an existing OS partition you bootc switch into), so FIRMWARE and BOOTLOADER are skipped.

unikernel

Single-binary payload that runs as PID 1 directly on the kernel — no userland, no init system. KERNEL is required; ENTRYPOINT must be binary. ROOTFS and INITRD are omitted.

container

The degenerate case: no boot chain at all. Standard OCI container image with a rootfs; runtime supplies PID 1 (ENTRYPOINT none).

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For the directive semantics behind each row, see the Specification. For working configurations of each target, see Examples.