sudo apt-get install qemu libncurses5-dev gcc-arm-linux-gnueabi build-essential

export ARCH=arm

export CROSS_COMPILE=arm-linux-gnueabi-

make menuconfig   选中静态编译

|

Busybox Settings  --->

    |

    [*] Build BusyBox as a static binary (no shared libs)

make install 

cd _install

mkdir etc dev mnt

mkdir -p etc/init.d/

cd etc/init.d/

vim rcS

mkdir -p /proc

mkdir -p /tmp

mkdir -p /sys

mkdir -p /mnt

/bin/mount -a

mkdir -p /dev/pts

mount -t devpts devpts /dev/pts

echo /sbin/mdev > /proc/sys/kernel/hotplug

mdev -s

chmod a+x rcS

cd ..

vim fstab

proc /proc proc defaults

tmpfs /tmp tmpfs defaults

sysfs /sys sysfs defaults

tmpfs /dev tmpfs defaults

debugfs /sys/kernel/debug defaults defaults  

vim inittab

::sysinit:/etc/init.d/rcS

::respawn:-/bin/sh

::askfirst:-/bin/sh

::ctrlaltdel:/bin/umount -a -r

cd ..

cd dev

sudo mknod console c

sudo mknod null c  3

拷贝交叉工具链的库到根文件系统
cp /opt/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi/arm-linux-gnueabi/libc/lib/*so* lib/ -d
cp /opt/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi/arm-linux-gnueabi/libc/usr/lib/*so* usr/lib -d

生成ext3镜像文件并挂载
  sudo dd if=/dev/zero of=a9rootfs.ext3 bs=1M count=32

mkfs.ext3 path/a9rootfs.ext3

mkdir tmpfs

sudo mount -t ext3 a9rootfs.ext3 tmpfs -o loop

sudo cp -r rootfs/*tmpfs

sudo umount tmpfs 

启动参数要添加-sd选项
进入系统执行mount -t ext3 /dev/mmcblk0 /mnt/  

export ARCH=arm

export CROSS_COMPILE=arm-linux-gnueabi-

make vexpress_defconfig

make menuconfig

General setup  --->

    [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support

    (_install) Initramfs source file(s) 

  ()  Default kernel command string

Kernel Features  --->

Memory split (3G/1G user/kernel split)  --->

(X) 3G/1G user/kernel split 

make bzImage -j4 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-

make dtbs
启动qemu

qemu-system-arm -M vexpress-a9 -smp  -m 1024M -kernel arch/arm/boot/zImage -append "rdinit=/linuxrc console=ttyAMA0 loglevel=8" -dtb arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic