AOSP源码里不包含内核源代码，需要单独下载。不同的内核对应不同的代码仓库，下面我们使用模拟器内核代码来学习。

下载模拟器对应的内核代码：

$ cd $WORKING_DIRECTORY
$ mkdir kernel
$ cd kernel
$ git clone https://android.googlesource.com/kernel/goldfish.git

被墙的话，使用国内镜像：

$ git clone https://aosp.tuna.tsinghua.edu.cn/kernel/goldfish

或

$ git clone git://mirrors.ustc.edu.cn/aosp/kernel/goldfish.git

切换到我们需要的分支：

$ git branch -a
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/android-3.10
  remotes/origin/android-3.18
  remotes/origin/android-3.4
  remotes/origin/android-goldfish-2.6.29
  remotes/origin/android-goldfish-3.10
  remotes/origin/android-goldfish-3.10-k-dev
  remotes/origin/android-goldfish-3.10-l-mr1-dev
  remotes/origin/android-goldfish-3.10-m-dev
  remotes/origin/android-goldfish-3.10-n-dev
  remotes/origin/android-goldfish-3.18
  remotes/origin/android-goldfish-3.18-dev
  remotes/origin/android-goldfish-3.4
  remotes/origin/android-goldfish-3.4-l-mr1-dev
  remotes/origin/android-goldfish-4.4-dev
  remotes/origin/heads/for/android-goldfish-3.18-dev
  remotes/origin/linux-goldfish-3.0-wip
  remotes/origin/master
$ git checkout android-goldfish-2.6.29

参考阅读

编译内核

Android2.3源码学习05 -- 下载内核源码

参考阅读