https://blog.night-shade.org.uk/2013/12/building-a-pure-debian-armhf-rootfs/

ubuntu

in jessie/Ubuntu 14.x (64bit) there are problems in second-stage: link, here debootstrap must be updated (first stage must be called again): download

sudo apt-get install qemu-user-static debootstrap binfmt-support
distro=buster
arch=armhf
#for bpi-r64 use arch=arm64
targetdir=$(pwd)/debian_${distro}_${arch}
mkdir $targetdir
sudo debootstrap --arch=$arch --foreign $distro $targetdir
sudo cp /usr/bin/qemu-arm-static $targetdir/usr/bin/
#for r64 use
# sudo cp /usr/bin/qemu-aarch64-static $targetdir/usr/bin/
sudo cp /etc/resolv.conf $targetdir/etc
sudo distro=$distro chroot $targetdir
export LANG=C
/debootstrap/debootstrap --second-stage

like it's done in source hostname,apt (local Server),…must be configured

• hostname (/etc/hostname)

bpi-r2

• /etc/apt/sources.list

deb http://ftp.us.debian.org/debian buster main contrib non-free
deb-src http://ftp.us.debian.org/debian buster main contrib non-free
deb http://ftp.us.debian.org/debian buster-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian buster-updates main contrib non-free
deb http://security.debian.org/debian-security buster/updates main contrib non-free
deb-src http://security.debian.org/debian-security buster/updates main contrib non-free

• fstab (boot,root)

# <file system>		<dir>	<type>	<options>		<dump>	<pass>
/dev/mmcblk0p1		/boot	vfat	errors=remount-ro	0	1
/dev/mmcblk0p2		/	ext4	defaults		0	0

• Dns-server in /etc/resolv.conf

nameserver 192.168.0.5

• Network-Configuration

auto eth0
iface eth0 inet manual
  pre-up ip link set $IFACE up
  post-down ip link set $IFACE down

auto lan0
iface lan0 inet static
  hwaddress ether 08:00:00:00:00:00 # if you want to set MAC manually
  address 192.168.0.10
  netmask 255.255.255.0
  gateway 192.168.0.5
  pre-up ip link set $IFACE up
  post-down ip link set $IFACE down
...

in existing Jessie-Image clear root-partition (except lib/modules/<kernelversion>) and put contents of Bootstrap-folder (debian_stretch) to it

Uploaded work so far on my gdrive

Image (sd+emmc in separate img's): gdrive

(deb_stretch_…)

on EMMC-Image SSH-Login is not possible as root because of missing option in ssh-server

add the following line to /etc/ssh/sshd_config and reboot/restart sshd:

PermitRootLogin yes

• clear logs (echo -n “”>logfile),
• delete backup-files,
• clear cache (e.g. APT),
• remove unused Kernel-Modules (/lib/modules/)
• delete own Users
• reset PW for root

fill free space in the Image with null-file (for better packing):

loopdev=$(losetup -f) #get first free loopdevice
losetup ${loopdev} /path/to/file
partprobe ${loopdev}
mount ${loopdev}p2 /mnt
 
#if you want to install/update things
cp /usr/bin/qemu-arm-static /mnt/usr/bin/
chroot /mnt
 
#overwrite free space
dd if=/dev/zero of=/mnt/null.dat
rm /mnt/null.dat
 
losetup -d ${loopdev}

https://softwarebakery.com/shrinking-images-on-linux

alternative https://wiki.debian.org/DebianInstaller/Arm/OtherPlatforms

you have ports wan, lan0-lan4 with kernel 4.14+

current config can be displayed using ip a or by editing /etc/network/interfaces

wan:dhcp # maybe needs additional "auto wan" to go up on boot
lan0: 192.168.0.10/24
lan1+lan2 are in a bridge with address 192.168.40.1/24 #currently also auto lanx+manual missing
lan3 unconfigured

to add default-gateway / DNS server do this

ip route add default via <your router ip>
nano /etc/resolv.conf #change ip of your gateway for DNS

for configuring keyboard you have to install console-setup then you will be prompted for keyboard-layout

apt-get install console-setup