mbv: clean up build

mbv/Makefile

@@ -23,20 +23,24 @@ sources += hal/uart/xuartlite.c hal/uart/xuartlite_stats.c hal/uart/xuartlite_in
 includes += -Ihal/uart
 
 bootloader_objects = bootloader.o start.o $(sources:.c=.o)
-app_objects = helloworld.o start.o $(sources:.c=.o)
+helloworld_objects = helloworld.o start.o $(sources:.c=.o)
+
+all_objects = $(bootloader_objects) $(helloworld_objects)
+deps = $(all_objects:.o=.d)
 
 CPPFLAGS += $(includes)
 
 %.bin: %.elf
 	$(OBJCOPY) -O binary $< $@
 
+%.elf: app.ld
+	$(LD) -Wl,-Tapp.ld $(LDFLAGS) -o $@ $(objects)
+
 bootloader.elf: $(bootloader_objects) bootloader.ld
 	$(LD) -Wl,-Tbootloader.ld $(LDFLAGS) -o $@ $(bootloader_objects)
 
-app.elf: $(app_objects) app.ld
-	$(LD) -Wl,-Tapp.ld $(LDFLAGS) -o $@ $(app_objects)
-
-deps = $(app_objects:.o=.d) $(bootloader_objects:.o=.d)
+helloworld.elf: objects = $(helloworld_objects)
+helloworld.elf: $(helloworld_objects)
 
 HOSTCXX = clang++
 HOSTLDFLAGS = -lgmock -lgtest -lgtest_main -L/usr/local/opt/llvm/lib -L/usr/local/lib
@@ -76,8 +80,12 @@ mktest:
 test_deps =
 
 .PHONY: bootloader
-bootloader:  ## Build the bootloader in a docker container
-	docker build -o . --target bootloader-export .
+bootloader:  ## Build the bootloader in docker
+	docker build -o . --target export --build-arg TARGET=bootloader.elf .
+
+.PHONY: helloworld
+helloworld:  ## Build the helloworld app in docker
+	docker build -o . --target export --build-arg TARGET=helloworld.bin .
 
 .PHONY: dev-image
 dev-image:
@@ -89,7 +97,7 @@ dev: dev-image  ## Run a dev container
 
 .PHONY: clean
 clean:  ## Remove generated files
-	rm -rf *.elf *.bin $(app_objects) $(bootloader_objects) $(deps)
+	rm -rf *.elf *.bin $(all_objects) $(deps)
 	rm -rf test/ *.dSYM $(test_deps) *.o
 
 .PHONY: help