编译android需要：
sudo apt-get install git-core gnupg flex bison gperf build-essential zip curl zlib1g-dev libc6-dev x11proto-core-dev libx11-dev libgl1-mesa-dev g++-multilib mingw32 tofrodos python-markdown libxml2-utils
编译kernel需要：
sudo apt-get install libncurses5-dev
sudo apt-get install mkimage