// install gcc toolchain
wget "https://releases.linaro.org/components/toolchain/binaries/latest/arm-eabi/gcc-linaro-7.3.1-2018.05-i686_arm-eabi.tar.xz"
tar -Jxf gcc-linaro-7.3.1-2018.05-i686_arm-eabi.tar.xz
export ROOT_BIN=/home/zzy/sda6/bin/gcc/gcc-linaro-7.3.1-2018.05-i686_arm-eabi/bin

sudo apt-get install gcc-arm-linux-gnueabi

// install qemu
wget "https://download.qemu.org/qemu-2.12.0.tar.xz"
tar -Jxf qemu-2.12.0.tar.xz
cd qemu-2.12.0/
mkdir build
cd build
../configure --prefix=/home/zzy/sda6/bin/qemu/qemu-2.12.0 --target-list="arm-softmmu,aarch64-softmmu" --audio-drv-list=alsa
/home/zzy/sda6/bin/qemu/

make -j8
make install

// some errors
ERROR: glib-2.12 gthread-2.0 is required to compiler QEMU
sudo apt-get install libglib2.0-dev

// install som package
sudo apt-get install libpixman-1-dev
sudo apt-get install flex

// busybox

wget "https://busybox.net/downloads/busybox-1.28.4.tar.bz2"
tar -jxf busybox-1.28.4.tar.bz2

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j8
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- install

git clone https://github.com/zzy-program/resource.git
cp -r resource/rootfs_arm32/* .
mk_rootfs.sh
The rootfs arm32_rootfs.ext4 will be created.

// build linux kernel
wget http://cdn.kernel.org/pub/linux/kernel/v3.x/linux-3.14.79.tar.xz
tar -Jxf linux-3.14.79.tar.xz
cd linux-3.14.79/
mkdir ../out_3.14.79
export ROOT_BIN=/home/zzy/sda6/bin/gcc/gcc-linaro-7.3.1-2018.05-i686_arm-eabi/bin
make ARCH=arm CROSS_COMPILE=$ROOT_BIN/arm-eabi- O=../out_3.14.79 vexpress_defconfig
make ARCH=arm CROSS_COMPILE=$ROOT_BIN/arm-eabi- O=../out_3.14.79 -j4 zImage

// run linux
/home/zzy/sda6/bin/qemu/qemu-2.12.0/bin/qemu-system-arm -M vexpress-a9 -m 512M -kernel ../out_3.14.79/arch/arm/boot/zImage -nographic -append "root=/dev/mmcblk0 console=ttyAMA0" -sd ../arm32_rootfs.ext4

git clone https://github.com/zzy-program/linux-3.14.79-study.git
mkdir ../out_3.14.79-study
export ROOT_BIN=/home/zzy/sda6/bin/gcc/gcc-linaro-7.3.1-2018.05-i686_arm-eabi/bin
make ARCH=arm CROSS_COMPILE=$ROOT_BIN/arm-eabi- O=../out_3.14.79-study vexpress_defconfig
make ARCH=arm CROSS_COMPILE=$ROOT_BIN/arm-eabi- O=../out_3.14.79-study -j4 zImage

/home/zzy/sda6/bin/qemu/qemu-2.12.0/bin/qemu-system-arm -M vexpress-a9 -m 512M -kernel ../out_3.14.79/arch/arm/boot/zImage -nographic -append "root=/dev/mmcblk0 console=ttyAMA0" -sd ../arm32_rootfs.ext4