The Debian installation is documented here as several points have to be considered. You should be familiar with Debian or be familiar using linux system commands on the command line.
download and install the firmware supporting Debian
Download https://github.com/gnubee-git/gnubee-git.github.io/raw/master/debian/openwrt-ramips-mt7621-gb-pc1-squashfs-sysupgrade_2017-03-01.bin (offical Kernel 3.10.14 from Soc vendor, support install to SD card)
https://github.com/gnubee-git/gnubee-git.github.io/raw/master/debian/librecmc-ramips-mt7621-gb-pc1-squashfs-sysupgrade_2017-11-28.bin (Kernel 4.4.87-gnu, with patches from Linux community, do not support install to SD card, because SD driver only work as a module)
Note: The firmware named “librecmc-ramips-mt7621-gb-pc1-squashfs-sysupgrade_2017-07-22.bin” has a bug with the network setup and is therefore NOT recommended! Details
Sha256sums: c2794439b241bd0f71ccfd84f337662b44e3d2b6b6a30593d2d03d8b4136ad openwrt-ramips-mt7621-gb-pc1-squashfs-sysupgrade_2017-03-01.bin e2fe4cd4f70dc04372d5a7dcf1443d6895cd3e797a65c1d9ec889d79db181493 librecmc-ramips-mt7621-gb-pc1-squashfs-sysupgrade_2017-11-28.bin
Upgrade your firmware using the downloaded file
The exact procedure is explained here
Reboot by entering the command
Access the newly installed kernel via SSH or the USB-2-UART
You can either activate the SSH access via built-in webserver on http://192.168.10.1 on eth0.1 (bridge-lan), connect the second Ethernet (eth0.2) to a switch and obtain an automatic address in your existing LAN, or use or via USB-2-UART, as explained in USB_to_UART
If you want to install Debian on a hard disk yo must format (at least) one partitions with the ext4 file system. Think a while on which partition scheme you want to use.
You can use
fdisk paritioning tool or partition the HD on another system. For my 1 TB hard disk I decide to create the following partitions using a GPT partition table:
/dev/sda1 1 GB ext4 named boot /dev/sda2 10 GB ext4 named data /dev/sda3 rest ext4 named data
Afterward run in the shell run the following commands
wget --no-check-certificate https://raw.githubusercontent.com/gnubee-git/GnuBee_Docs/master/GB-PCx/scripts/jessie_3.10.14/debian-jessie-install sh debian-jessie-install
You will be asked where (what device) to install debian on. In my case I used /dev/sda2. You find the complete log here.
Once if finishes type
reboot and the new debian system should come up. You find the boot log here.
If you want to access the new Debian system via ssh, you must connect now the blue RJ-45 to your network and consult your DHCP server to see, which IP-address was assigned to it. In my case it was 192.168.0.73 and running
ssh firstname.lastname@example.org got me to the login.
Once Debian is up you may log in as user root with the password GnuBee. You should change it.
Install kernel modules
You must install more kernel modules running the following commands
wget https://raw.githubusercontent.com/gnubee-git/gnubee-git.github.io/master/debian/debian-modules-install sh debian-modules-install
Install more packages
Now you are ready to install more packages. There are quite a few I cannot live without, there I ran
apt-get update apt-get install vim-nox etckeeper htop iotop parted smartmontools