android 幾個快速編譯images指令

Android比较重要的三个img文件：

• make systemimage - system.img
• make userdataimage - userdata.img
• make ramdisk - ramdisk.img
• make snod - 快速打包system.img (with this command, it will build a new system.img very quickly. well, you cannot use “make snod” for all the situations. it would not check the dependences. if you change some code in the framework which will effect other applications)

因為
system.img 是 從 out/target/product/xxxx/system 做出來的。
如果改了 這個 folder 的內容，想要重新產生 system.img。不要管 system folde 裡面的 file 的 dependency，可以用 snod 這個 target:

• make snod

定義在 build/core/Makefile 可以看到 snod 這個 target: 
(有說明是： make system.img ignoring depencies)

.PHONY: systemimage-nodeps snod
systemimage-nodeps snod: $(filter-out systemimage-nodeps snod,$(MAKECMDGOALS)) \
| $(INTERNAL_MKUSERFS)
@echo "make $@: ignoring dependencies"
$(call build-systemimage-target,$(INSTALLED_SYSTEMIMAGE))
$(hide) $(call assert-max-image-size,$(INSTALLED_SYSTEMIMAGE),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE),yaffs)