接上篇 （Ubuntu12.04编译Android4.0.1源码全过程），编译好后在目录/media/娱乐/androidSource/out/target/product/generic 下有三个镜像文件：ramdisk.img, userdata.img, system.img，模拟器运行除了这三个镜像文件外，还需要/media/娱乐/androidSource/prebuilt/android-arm/kernel 目录下的kernel-qemu文件。为了运行模拟器，sudo gedit /etc/profile设置环境变量：

export PATH=$PATH:/media/娱乐/androidSource/out/host/linux-x86/bin
export ANDROID_PRODUCT_OUT=/media/娱乐/androidSource/out/target/product/generic

       然后source /etc/profile. 启动模拟器的命令emulator就在/media/娱乐/androidSource/out/host/linux-x86/bin目录下，当emulator没有任何参数时会使用ANDROID_PRODUCT_OUT目录下的三个镜像及上面的kernel-qemu文件。终端运行emulator后就会启动模拟器，出现：emulator: WARNING: system partition size adjusted to match image file (163 MB > 66 MB) 这样的警告。也可以用如下命令指定内核和那三个镜像：emulator -kernel ./prebuilt/android-arm/kernel/kernel-qemu -sysdir ./out/target/product/generic -system system.img -data userdata.img -ramdisk ramdisk.img

       上面的内核是google编译好的，为了自己编译内核需要自己下载内核源码。下载步骤：

1，创建目录mkdir /home/yan/kernel, 在这个目录下，终端输入：git clone http://android.googlesource.com/kernel/goldfish.git

会看到以下提示：

Cloning into 'goldfish'...
remote: Sending approximately 499.97 MiB ...
remote: Counting objects: 41051, done
remote: Finding sources: 100% (144/144)
remote: Getting sizes: 100% (72/72)
remote: Compressing objects: 100% (314839/314839)
remote: Total 2442786 (delta 2048918), reused 2442751 (delta 2048913)
Receiving objects: 100% (2442786/2442786), 499.75 MiB | 408 KiB/s, done.
Resolving deltas: 100% (2049084/2049084), done.

这时kernel目录下有个goldfish目录，但里面是空的，有个隐藏文件.git，这时并未下载到内核，仅仅是创建了仓库[这时的goldfish文件夹有500M左右，压缩文件下载链接： 下载后，直接解压就可以按下面步骤选定下载的内核版本了]。终端：git branch -a看到以下信息：

yan@ubuntu:~/kernel/goldfish$ git branch -a
* masterremotes/origin/HEAD -> origin/masterremotes/origin/android-goldfish-2.6.29remotes/origin/android-goldfish-3.4remotes/origin/linux-goldfish-3.0-wipremotes/origin/master

选择2.6.29版本，然后输入以下信息下载：

yan@ubuntu:~/kernel/goldfish$ git checkout remotes/origin/android-goldfish-2.6.29

        快下载完时，看到如下信息：

Checking out files: 100% (26821/26821), done.
Note: checking out 'remotes/origin/android-goldfish-2.6.29'.You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:git checkout -b new_branch_nameHEAD is now at e3d684d... enable FUSE for sdcard emulation

         这就表示内核下载完毕。文件夹goldfish除去上面的隐藏文件夹.git, 大小为360M，压缩文件下载链接：http://ajh59wyr6i.l9.yunpan.cn/lk/QteFfbQWrhmh6 下载后可以直接按下面步骤进行编译。为了编译内核，需要如下步骤：

1，设置交叉编译器路径：

              export PATH=$PATH:/media/娱乐/androidSource/prebuilt/linux-x86/toolchain/arm-eabi-4.4.3/bin

2，修改goldfish目录下的Makefile文件的以下两行为：

3，输入：make goldfish_armv7_defconfig，这里注意如果输入make goldfish_defconfig编译好的内核在启动时，将启动不了，一直黑屏。最初我弄的也是黑屏启动不了，参考后面参考2才找到答案。

看到如下信息：

yan@ubuntu:~/kernel/goldfish$ make goldfish_armv7_defconfigHOSTCC  scripts/basic/fixdep
scripts/basic/fixdep.c: In function ‘traps’:
scripts/basic/fixdep.c:377: warning: dereferencing type-punned pointer will break strict-aliasing rules
scripts/basic/fixdep.c:379: warning: dereferencing type-punned pointer will break strict-aliasing rulesHOSTCC  scripts/basic/docprocHOSTCC  scripts/basic/hashHOSTCC  scripts/kconfig/conf.o
scripts/kconfig/conf.c: In function ‘conf_askvalue’:
scripts/kconfig/conf.c:105: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
scripts/kconfig/conf.c: In function ‘conf_choice’:
scripts/kconfig/conf.c:307: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_resultHOSTCC  scripts/kconfig/kxgettext.oSHIPPED scripts/kconfig/zconf.tab.cSHIPPED scripts/kconfig/lex.zconf.cSHIPPED scripts/kconfig/zconf.hash.cHOSTCC  scripts/kconfig/zconf.tab.oHOSTLD  scripts/kconfig/conf
arch/arm/configs/goldfish_defconfig:289:warning: override: FB_EARLYSUSPEND changes choice state
#
# configuration written to .config
#

           输入make或make -j4就可以编译了，带参数-j4，表示cpu为双核，速度快了很多，大概不到3分钟内核就编译完了。编译完成时可以看到：

GEN     .versionCHK     include/linux/compile.hUPD     include/linux/compile.hCC      init/version.oLD      init/built-in.oLD      .tmp_vmlinux1KSYM    .tmp_kallsyms1.SAS      .tmp_kallsyms1.oLD      .tmp_vmlinux2KSYM    .tmp_kallsyms2.SAS      .tmp_kallsyms2.oLD      vmlinuxSYSMAP  System.mapSYSMAP  .tmp_System.mapOBJCOPY arch/arm/boot/ImageKernel: arch/arm/boot/Image is readyAS      arch/arm/boot/compressed/head.oGZIP    arch/arm/boot/compressed/piggy.gzAS      arch/arm/boot/compressed/piggy.oCC      arch/arm/boot/compressed/misc.oLD      arch/arm/boot/compressed/vmlinuxOBJCOPY arch/arm/boot/zImageKernel: arch/arm/boot/zImage is ready

生成的内核在/home/yan/kernel/goldfish/arch/arm/boot文件夹下。

4，用这个编译好的内核和编译源码产生的3个镜像安装至模拟器。

        终端中输入：

        yan@ubuntu:~/kernel/goldfish$ emulator -kernel /home/yan/kernel/goldfish/arch/arm/boot/zImage &

注意这个&号是让程序在后台运行，如果这样输入，会显示以下警告：

 emulator: WARNING: system partition size adjusted to match image file (163 MB > 66 MB)

为此，启动命令更改为：

  emulator -kernel /home/yan/kernel/goldfish/arch/arm/boot/zImage -partition-size 500 &

        如果后面带&，模拟器启动后终端会自动释放，然后还可以接着输入命令：adb shell，然后cd /proc，然后cat version查看机器所用的内核版本。如果后面不带&，启动模拟器的终端就不会释放，用户也无法在此终端输入后续命令。这时可以新开一个终端，输入上面同样的命令查看内核版本信息。

       其实可以在emulator命令时带个-shell参数，相当于在启动模拟器的终端输入adb shell命令了。因此，我推荐的启动命令是：

emulator -kernel /home/yan/kernel/goldfish/arch/arm/boot/zImage -partition-size 500 -shell
        如果用系统自带的默认内核，cat version查看的结果是：

# cat version
Linux version 2.6.29-g327fbfb (digit@lulu.par.corp.google.com) (gcc version 4.4.3 (GCC) ) #10 Thu Oct 6 00:37:14 CEST 2011

        如果用刚编译好的内核，查看的结果是：

# cat version
Linux version 2.6.29 (yan@ubuntu) (gcc version 4.4.3 (GCC) ) #2 Fri Jul 12 19:09:31 CST 2013

虽然都是2.6.29内核，但从后面的日期和linux版本不难看出，新编译的内核成功加载至模拟器了。

参考：

1，老罗：在Ubuntu上下载、编译和安装Android最新内核源代码（Linux Kernel）

2，http://blog.csdn.net/mr_president/article/details/7689084

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