update lab8 Makefile: for disk0 DIR

code/lab8/Makefile

@@ -3,8 +3,6 @@ EMPTY	:=
 SPACE	:= $(EMPTY) $(EMPTY)
 SLASH	:= /
 
-V       := @
-
 # try to infer the correct GCCPREFX
 ifndef GCCPREFIX
 GCCPREFIX := $(shell if i386-ucore-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
@@ -261,6 +259,9 @@ endef
 
 $(foreach p,$(USER_BINS),$(eval $(call fscopy,$(p),$(SFSROOT)$(SLASH))))
 
+$(SFSROOT):
+	if [ ! -d "$(SFSROOT)" ]; then mkdir $(SFSROOT); fi
+
 $(SFSIMG): $(SFSROOT) $(SFSBINS) | $(call totarget,mksfs)
 	$(V)dd if=/dev/zero of=$@ bs=1M count=128
 	@$(call totarget,mksfs) $@ $(SFSROOT)