add depend target, and use the depend to make files to pass to entr to run build..

Makefile

@@ -34,11 +34,19 @@ CFLAGS+= -Werror -Wall
 .PHONY: all
 all: $(PROG)$(PROGEXT) $(PROG).list
 
+.PHONY: depend
+depend: $(SRCS)
+	$(ARMCC) $(ARMTARGET) $(CFLAGS) $(.ALLSRC) -MM > .depend || rm -f .depend
+
 $(PROG)$(PROGEXT): $(OBJS)
 	$(ARMCC) $(ARMTARGET) -o $@ $(.ALLSRC) -T$(LINKER_SCRIPT) --specs=nosys.specs -Wl,--gc-sections -static --specs=nano.specs -Wl,--start-group -lc -lm -Wl,--end-group
 
 $(PROG).list: $(PROG)$(PROGEXT)
-	$(ARMOBJDUMP) -h -S $(.ALLSRC) > $@
+	$(ARMOBJDUMP) -h -S $(.ALLSRC) > $@ || rm -f $@
+
+.PHONY: runbuild
+runbuild:
+	for i in $$(gsed ':x; /\\$$/ { N; s/\\\n//; tx }' < .depend  | sed -e 's/^[^:]*://'); do echo $$i; done | entr -d sh -c 'cd $(.CURDIR) && $(MAKE) all'
 
 .PHONY: runtests
 runtests: