记录一下下载内核的命令，以免每次都去找。
# download linux kernel
#try folliwing three commands. if the first can't work, try the second one...
git clone git://git.kernel.org/pub/scm/Linux/kernel/git/stable/linux-stable.git
git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
git clone https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable.git
the links can be got from:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/
git clone git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git
#download android kernel
#git clone https://android.googlesource.com/kernel/common.git googlekernel
git clone https://android.googlesource.com/kernel/goldfish.git
git clone https://android.googlesource.com/kernel/msm.git
git clone https://android.googlesource.com/kernel/omap.git
git clone https://android.googlesource.com/kernel/samsung.git
git clone https://android.googlesource.com/kernel/tegra.git
下载android代码：
http://www.codesec.net/view/463294.html
Ubuntu 下 Android 源码以及内核下载与编译
本教程是基于Ubuntu下Android6.0.1源码以及内核的下载和编译