Makefile: add more targets

Signed-off-by: Kornilios Kourtis <[email protected]>

Makefile

@@ -12,6 +12,8 @@ KERNEL_VERSIONS=4.19 5.4 5.10 bpf-next
 .PHONY: all
 all:
 	@echo "Available targets:"
+	@echo "  images_builder:   build root fs builder images"
+	@echo "  kernels_builder:  build root kernel builder images"
 	@echo "  images:           build root fs images"
 	@echo "  kernels:          build root kernel images"
 	@echo "  quay-dockerfiles: create dockerfiles for quay builder"
@@ -24,14 +26,20 @@ quay-dockerfiles:
 	done
 
 
-.PHONY: images
-images:
+.PHONY: images_builder
+images_builder:
 	$(DOCKER) build -f dockerfiles/root-builder -t $(ROOT_BUILDER) .
+
+.PHONY: images
+images: images_builder
 	$(DOCKER) build -f dockerfiles/root-images  -t $(ROOT_IMAGES)  .
 
-.PHONY: kernels
-kernels:
+.PHONY: kernels_builder
+kernels_builder:
 	$(DOCKER) build -f dockerfiles/kernel-builder -t $(KERNEL_BUILDER) .
+
+.PHONY: kernels
+kernels: kernels_builder
 	for v in $(KERNEL_VERSIONS) ; do \
 		$(DOCKER) build --build-arg KERNEL_VER=$$v -f dockerfiles/kernel-image -t $(KERNEL_IMAGES):$$v . ; \
 	done