[Unit]
Description=Mount Gentoo chroot Volume/s at boot
## Gentoo on disk vol //dev/vdb  host Debian-9 arm64...
## https://wiki.gentoo.org/wiki/Chroot  addapt...
## Prepare Chroot on bootup , just chroot /gentoo-arm64 and done should be the end all...
[Mount]
start() {
    cp /etc/resolv.conf /mnt/gentoo-arm64/etc
     ebegin "Mounting chroot directories"
     mount /dev/vdb1 /gentoo-arm64/boot/efi
     mount /dev/vdb2 /gentoo-arm64/boot/
     mount /dev/vdb3 /gentoo-arm64/

     mount -o rbind /dev /gentoo-arm64/dev > /dev/null &
     mount -t proc none /gentoo-arm64/proc > /dev/null &
     mount -o bind /sys /gentoo-arm64/sys > /dev/null &
     mount -o bind /tmp /gentoo-arm64/tmp > /dev/null &
     Echo "chroot ready for users/devs"
}

Options=defaults

[Install]
WantedBy=multi-user.target