Add Makefile with targets to build docker/rootfs

Author: MattBlack85

Makefile

@@ -0,0 +1,39 @@
+PLATFORMS?=linux/arm64
+IMAGE?=archlinuxarm
+
+.PHONY: qemu
+qemu:
+	docker run --privileged --rm tonistiigi/binfmt --install arm64
+
+# --- Builds ---
+.PHONY: build-minimal
+build-minimal:
+	docker buildx build \
+	  --platform $(PLATFORMS) \
+	  -t $(IMAGE):minimal-aarch64 \
+          -f dockerfiles/Dockerfile.base \
+          --target archarm \
+          --load \
+	  .
+
+.PHONY: export
+export:
+	docker buildx build \
+          --platform $(PLATFORMS) \
+          -t $(IMAGE):minimal-aarch64-export \
+          -f dockerfiles/Dockerfile.base.aarch64 \
+	  --target export \
+          --load .
+
+.PHONY: create-rootfs-container
+create-rootfs-container:
+	docker create --platform=linux/arm64 --name take $(IMAGE):minimal-aarch64-export sh
+
+.PHONY: copy-rootfs-tar
+copy-rootfs-tar:
+	docker cp take:/archlinuxarm-aarch64-rootfs.tar ./rootfs.tar
+	docker rm -f take
+
+.PHONY: prepare-rpi-img
+prepare-rpi-image: export create-rootfs-container copy-rootfs-tar
+	./scripts/build_img.sh