编译cubieboard android 源码过程详解之（五）：make

前期准备终于做完了，设置好了环境变量，提供了所需的函数，相关文件也已经到位，所有这一且都是为了最终的make。

首先是Makefile的包含关系：

Makefile

build/core/main.mk

build/core/help.mk

build/core/config.mk

build/core/pathmap.mk

buildspec.mk

device/softwinner/apollo-cubieboard/BoardConfig.mk

device/softwinner/crane-common/BoardConfigCommon.mk

build/core/combo/select.mk

build/core/combo/HOST_linux-x86.mk

build/core/combo/TARGET_linux-arm.mk

build/core/combo/javac.mk

build/core/dumpvar.mk

build/core/cleanbuild.mk

很多和 clean 相关的 Makefile，这里不再列出

out/versions_checked.mk

发现我错了，这简直是个无底洞啊，后面分析的时候有些Makefile就不展开了或是只局部分析。想到用脚本来打印这个列表的，但是发现include Makefile时，有些路径包含变量，不得不放弃了。其实我更关心的是和硬件相关的Makefile。

make命令是在 “android” 目录下执行的，依照make的用法，在该目录下找到 Makefile 文件：

Makefile

1 ### DO NOT EDIT THIS FILE ###
2 include build/core/main.mk
3 ### DO NOT EDIT THIS FILE ###

只有一行有效语句，就是包含了 “build/core/main.mk” 文件，顺藤摸瓜：

build/core/main.mk

 1 # Only use ANDROID_BUILD_SHELL to wrap around bash.
 2 # DO NOT use other shells such as zsh.
 3 ifdef ANDROID_BUILD_SHELL
 4 SHELL := $(ANDROID_BUILD_SHELL)
 5 else
 6 # Use bash, not whatever shell somebody has installed as /bin/sh
 7 # This is repeated in config.mk, since envsetup.sh runs that file
 8 # directly.
 9 SHELL := /bin/bash
10 endif

对shell类型有严格的限制，只能用 “$(ANDROID_BUILD_SHELL)” 或 “bash”，这样可以避免一些兼容性问题。

build/core/main.mk

1 # this turns off the suffix rules built into make
2 .SUFFIXES:
3 
4 # this turns off the RCS / SCCS implicit rules of GNU Make
5 % : RCS/%,v
6 % : RCS/%
7 % : %,v
8 % : s.%
9 % : SCCS/s.%

见注释，关闭一些规则，但现在还没弄懂（TODO）。

build/core/main.mk

1 # If a rule fails, delete $@.
2 .DELETE_ON_ERROR:

如果规则的命令执行错误，将删除已经被修改的目标文件。

build/core/main.mk

 1 # check for broken versions of make
 2 ifeq (0,$(shell expr $$(echo $(MAKE_VERSION) | sed "s/[^0-9\.].*//") = 3.81)) #只能使用make 3.81
 3 $(warning ********************************************************************************)
 4 $(warning *  You are using version $(MAKE_VERSION) of make.)
 5 $(warning *  Android can only be built by version 3.81.)
 6 $(warning *  see http://source.android.com/source/download.html)
 7 $(warning ********************************************************************************)
 8 $(error stopping)
 9 endif
10 
11 TOP := .
12 TOPDIR :=
13 
14 BUILD_SYSTEM := $(TOPDIR)build/core

build/core/main.mk

1 # This is the default target.  It must be the first declared target.
2 .PHONY: droid
3 DEFAULT_GOAL := droid
4 $(DEFAULT_GOAL):
5 
6 # Used to force goals to build.  Only use for conditionally defined goals.
7 .PHONY: FORCE
8 FORCE:

默认目标为 “droid”，没有什么依赖，直接执行下面的命令。

build/core/main.mk

1 # Targets that provide quick help on the build system.
2 include $(BUILD_SYSTEM)/help.mk

build/core/help.mk

 1 ifeq ($(MAKECMDGOALS),help)
 2 dont_bother := true
 3 endif
 4 ifeq ($(MAKECMDGOALS),out)
 5 dont_bother := true
 6 endif
 7 
 8 .PHONY: help
 9 help:
10     @echo
11     @echo "Common make targets:"
12     @echo "----------------------------------------------------------------------------------"
13     @echo "droid                   Default target"
14     @echo "clean                   (aka clobber) equivalent to rm -rf out/"
15     @echo "snod                    Quickly rebuild the system image from built packages"
16     @echo "offline-sdk-docs        Generate the HTML for the developer SDK docs"
17     @echo "doc-comment-check-docs  Check HTML doc links & validity, without generating HTML"
18     @echo "libandroid_runtime      All the JNI framework stuff"
19     @echo "framework               All the java framework stuff"
20     @echo "services                The system server (Java) and friends"
21     @echo "help                    You're reading it right now"
22 
23 .PHONY: out
24 out:
25     @echo "I'm sure you're nice and all, but no thanks."

提供一些帮助。当然这个目标不手动调用是不会执行的，这里不做分析。

build/core/main.mk

1 # Set up various standard variables based on configuration
2 # and host information.
3 include $(BUILD_SYSTEM)/config.mk

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编译cubieboard android 源码过程详解之（五）：make

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