０：重要文件
在下面的目錄中包含了編譯過程中調用的makefile.很重要的。
[root@localhost /openwrt/openwrt/trunk/include]$ls
autotools.mk device_table.txt.bak kernel-build.mk Makefile package-dumpinfo.mk quilt.mk site uclibc++.mk
cmake.mk download.mk kernel-defaults.mk netfilter.mk package-ipkg.mk rules.mk subdir.mk unpack.mk
debug.mk host-build.mk kernel.mk nls.mk package.mk scan.mk target.mk verbose.mk
depends.mk host.mk kernel-version.mk package-bin.mk prereq-build.mk scons.mk toolchain-build.mk version.mk
device_table.txt image.mk ltqtapi.mk
1：內核編譯：
現在了最新的open的trunk之後， /openwrt/openwrt/trunk中的makefile是總的編譯開始，其中有如下內容：
include $(TOPDIR)/include/host.mk
ifneq ($(OPENWRT_BUILD),1)
_SINGLE=export MAKEFLAGS=$(space);
override OPENWRT_BUILD=1
export OPENWRT_BUILD
GREP_OPTIONS=
export GREP_OPTIONS
include $(TOPDIR)/include/debug.mk
include $(TOPDIR)/include/depends.mk
include $(TOPDIR)/include/toplevel.mk
else
include rules.mk
include $(INCLUDE_DIR)/depends.mk
include $(INCLUDE_DIR)/subdir.mk
include target/Makefile
include package/Makefile
include tools/Makefile
include toolchain/Makefile
其中在此處關注的是文件 include target/Makefile
其中首先看看
$(curdir)/builddirs:=linux sdk imagebuilder toolchain
$(curdir)/builddirs-default:=linux 可以看到在此目錄下面有：/openwrt/openwrt/trunk/target/linux中的makefile
include $(INCLUDE_DIR)/target.mk
export TARGET_BUILD=1
prereq clean download prepare compile install menuconfig nconfig oldconfig update refresh: FORCE
@+$(NO_TRACE_MAKE) -C $(BOARD) $@
其中NO_TRACE_MAKE 就是在頂層通過make menuconfig時配置的目標是什麼，此處選擇是ar71xx。
因此在看看ar71xx中的makefile是怎麼定義的。
include $(TOPDIR)/rules.mk
ARCH:=mips 當前的CPU是MIPS
BOARD:=ar71xx 板子類型
BOARDNAME:=Atheros AR7xxx/AR9xxx
FEATURES:=mips16
CPU_TYPE=34kc
SUBTARGETS:=generic nand mikrotik
LINUX_VERSION:=3.10.36 內核版本
include $(INCLUDE_DIR)/target.mk
DEFAULT_PACKAGES += \
kmod-gpio-button-hotplug swconfig kmod-ath9k wpad-mini uboot-envtools 必須編譯的模塊
$(eval $(call BuildTarget)) 需要實際執行的目標。
下面來看看BuildTarget的定義：