to setup debootstrap env

# mount -t proc /proc /opt/test/dual_rootfs/proc
# mount -t sysfs /sys /opt/test/dual_rootfs/sys
# mount --bind /dev /opt/test/dual_rootfs/dev
# mount --bind /dev/pts /opt/test/dual_rootfs/dev/pts
# chroot /opt/test/dual_rootfs /debootstrap/debootstrap --second-stage