转载：
https://whycan.com/t_3922.html
环境：ubuntu 16.04
sudo apt-get install debootstrap
mkdir buster
wget https://ftp-master.debian.org/keys/release-10.asc -qO- | gpg --import --no-default-keyring --keyring ./debian-release-10.gpg
#debootstrap --keyring=./debian-release-10.gpg --variant=minbase buster buster http://ftp.cn.debian.org/debian/
debootstrap --keyring=./debian-release-10.gpg --foreign --verbose --arch=armhf stretch rootfs http://ftp2.cn.debian.org/debian注意，根据buster说明建议最小内存是 256MB
https://www.debian.org/releases/stable/armhf/ch03s04.en.html
而之前的stretch是128MB
https://www.debian.org/releases/stretch/amd64/ch03s04.html.en
debian镜像列表
https://www.debian.org/mirror/list
如何制作rootfs的基础说明debootstrap
https://wiki.debian.org/Debootstrap
https://linux-sunxi.org/Debootstrap
跟着就要进行第二步了，请参考
https://whycan.cn/t_2666.html