PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.3
TARGET_PRODUCT=full
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a
TARGET_CPU_VARIANT=generic
HOST_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-3.13.0-32-generic-x86_64-with-Ubuntu-12.04-precise
HOST_BUILD_TYPE=release
BUILD_ID=JWR66V
OUT_DIR=out
就是它定义的一些变量以及值