INSTALL_FAILED_OLDER_SDK Fails

我的应用也是通过在manifest中添加android.uid.system和在Android.mk中添加LOCAL_CERTIFICATE := platform，然后MMM编译以获取次特权。但是我通过MMM编译出来的APK不能在系统提供的SDK中创建的AVD里安装，提示Failure [INSTALL_FAILED_OLDER_SDK]。问题原因如下：

/build/core/version_defaults.mk文件中这一段

ifeq "" "$(DEFAULT_APP_TARGET_SDK)"
  # This is the default minSdkVersion and targetSdkVersion to use for
  # all .apks created by the build system.  It can be overridden by explicitly
  # setting these in the .apk's AndroidManifest.xml.  It is either the code
  # name of the development build or, if this is a release build, the official
  # SDK version of this release.
  ifeq "REL" "$(PLATFORM_VERSION_CODENAME)"
    DEFAULT_APP_TARGET_SDK := $(PLATFORM_SDK_VERSION)
  else
    DEFAULT_APP_TARGET_SDK := $(PLATFORM_VERSION_CODENAME)
  endif
endif

将DEFAULT_APP_TARGET_SDK直接赋值相应的API等级即可。