购买Nexus手机的朋友大多是为了自己修改系统玩，再加上其较高的性价比，在开发者中还是广受欢迎的。我的5太子被我升级到了6.0预览版，玩的正嗨，舍不得换回到5.1时代了。不过鉴于距6.0源码发布还有段日子，5.1的源码编译与烧写仍是主流，下面就记录了整个过程（持续了很长时间，我们要有耐心）。

搭建开发环境

系统推荐Ubuntu 14.04
1.openjdk is needed

$ sudo apt-get update$ sudo apt-get install openjdk-7-jdk

set it the default java version

$ sudo update-alternatives --config java$ sudo update-alternatives --config javac

2.required package

sudo apt-get install bison g++-multilib git gperf libxml2-utils make python-networkx zlib1g-dev:i386 zip

遇到问题:

$ sudo apt-get install bison g++-multilib git gperf libxml2-utils make python-networkx zlib1g-dev:i386 zip[sudo] password for linc: Reading package lists... DoneBuilding dependency tree       Reading state information... Donemake is already the newest version.zip is already the newest version.git is already the newest version.git set to manually installed.libxml2-utils is already the newest version.libxml2-utils set to manually installed.Some packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: g++-multilib : Depends: gcc-multilib (>= 4:4.8.2-1ubuntu6) but it is not going to be installedE: Unable to correct problems, you have held broken packages

按照如下步骤即可：

$ sudo apt-get install g++-multilib$ sudo apt-get install  bison git gperf libxml2-utils make python-networkx zlib1g-dev:i386 zip

gcc为必须

$ sudo apt-get install gcc$ gcc -vThread model: posixgcc version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04) 

repo

$ mkdir ~/bin$ PATH=~/bin:$PATH$ curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo$ chmod a+x ~/bin/repo

check sh1 sum:

$ sha1sum repo b8bd1804f432ecf1bab730949c82b93b0fc5fede  repo

For version 1.21, the SHA-1 checksum for repo is b8bd1804f432ecf1bab730949c82b93b0fc5fede

repo init

针对Nexus5的5.1.1的初始化如下：

LMY48I  android-5.1.1_r9    Lollipop    Nexus 4, Nexus 5, Nexus 6, Nexus 7 (flo), Nexus 9 (volantis/volantisg), Nexus 10

$ repo init -u https://android.googlesource.com/platform/manifest -b android-5.1.1_r9Your identity is: linc <[email protected].com>If you want to change this, please re-run 'repo init' with --config-nameTesting colorized output (for 'repo diff', 'repo status'):  black    red      green    yellow   blue     magenta   cyan     white   bold     dim      ul       reverse repo has been initialized in /home/linc/source-android/android-source

repo sync

$ repo sync

一个晚上两个白天，终于下载完成，代码达34G.

Setting up ccache

Put the following in your .bashrc (or equivalent):

export USE_CCACHE=1

run the command:

prebuilts/misc/linux-x86/ccache/ccache -M 50G

Building the System

1.Set up environment

$ source build/envsetup.sh

or

$ . build/envsetup.sh

2.Choose a Target

$ lunch You're building on LinuxLunch menu... pick a combo:     1. aosp_arm-eng     2. aosp_arm64-eng     3. aosp_mips-eng     4. aosp_mips64-eng     5. aosp_x86-eng     6. aosp_x86_64-eng     7. aosp_manta-userdebug     8. aosp_flo-userdebug     9. aosp_deb-userdebug     10. full_fugu-userdebug     11. aosp_fugu-userdebug     12. aosp_tilapia-userdebug     13. aosp_grouper-userdebug     14. aosp_mako-userdebug     15. aosp_hammerhead-userdebug     16. aosp_flounder-userdebug     17. aosp_shamu-userdebug     18. mini_emulator_x86-userdebug     19. mini_emulator_arm64-userdebug     20. mini_emulator_x86_64-userdebug     21. mini_emulator_mips-userdebug     22. m_e_arm-userdebugWhich would you like? [aosp_arm-eng] 

Nexus5就选择了15，如果只是用于模拟器就选择1好了。
3.build

make -j4

如果遇到等待其他任务完成的错误，是多线程冲突，就直接make好了。
4.error
1)

No private recovery resources for TARGET_DEVICE hammerheadhost C++: bcc <= frameworks/compile/libbcc/tools/bcc/Main.cppclang++: error: unable to execute command: Executable "as" doesn't exist!clang++: error: assembler command failed with exit code 1 (use -v to see invocation)make: *** [out/host/linux-x86/obj32/EXECUTABLES/bcc_intermediates/Main.o] Error 1

try make clean.这是没有安装gcc的后果。

build successfully

#### make completed successfully (05:53:54 (hh:mm:ss)) ####

目录结构如下：

out/target/product/hammerhead$ du -sh *4.0K    android-info.txt8.8M    boot.img4.0K    cache14M cache.img64K clean_steps.mk172K    data4.0K    fake_packages81M gen64K installed-files.txt8.1M    kernel16G obj4.0K    previous_build_config.mk700K    ramdisk.img1.4M    ramdisk-recovery.img2.2M    recovery9.5M    recovery.img1.3M    root2.9G    symbols288M    system307M    system.img135M    userdata.img

Flash device

To flash a device, you will need to use fastboot, which should be included in your path after a successful build. Place the device in fastboot mode either manually by holding the appropriate key combination at boot, or from the shell with

$ adb reboot bootloader

Once the device is in fastboot mode, run

$ fastboot flashall -w

The -w option wipes the /data partition on the device; this is useful for your first time flashing a particular device but is otherwise unnecessary.

For more information about building for and running on actual hardware, see Running Builds.

Flash emulator

1.build generic img
lunch 1即可，然后正常make。

make completed successfully (05:02:47 (hh:mm:ss))

2.启动模拟器

~/source-android/android-source/out/target/product/generic$ emulator -sysdir ~/source-android/android-source/out/target/product/generic -system system.img emulator: WARNING: system partition size adjusted to match image file (550 MB > 200 MB)emulator: WARNING: data partition size adjusted to match image file (550 MB > 200 MB)Creating filesystem with parameters:    Size: 69206016    Block size: 4096    Blocks per group: 32768    Inodes per group: 4224    Inode size: 256    Journal blocks: 1024    Label:     Blocks: 16896    Block groups: 1    Reserved block group size: 7Created filesystem with 11/4224 inodes and 1302/16896 blocks

模拟器顺利启动，与真机的区别有很多，比如开机画面不同，Home的UI和操控都有所不同。具体原因敬请期待。