Debian on OpenWrt One

The Openwrt One is a nice open hardware access point, running OpenWrt by default. As the hardware is reasonably powerful and expandable, running a more general purpose OS like Debian on it can be rather convenient.

The onboard storage (NAND) flash is 256MiB, which Debian can be made to fit. However it's somewhat inconvenient and limiting. Luckily there is an M.2 slot on the board to expand the storage via e.g. an NVME, which this repo helps installing Debian on. Note The goal here is to just make it easy to install an initial Debian image on the OpenWrt One. Not to provide a polished end-user access-point experience, like e.g. OpenWrt provides.

Requirements:

• OpenWrt one
• NVME fitted in the device
• Serial console access (front type-c port, baudrate 115200)
• USB stick for installation

All artifacts for installation steps can be downloaded from the latest build (openwrt*) and should be placed on a USB stick (single FAT partition).

Installation:

The installation comes in two parts; First the NAND flash content is replaced with a u-boot capable of directly booting from NVME as well as recovery image to help with flashing the NVME and potentially debugging system issues. As a second step a Debian system image will be installed to the NVME.

Flashing NAND:

To (re)flash NAND, the system is booted from NOR flash and NAND rewritten from USB; To do this:

• Format a USB stick with a single FAT partition
• Download and put on the stick:
  • openwrt-mediatek-filogic-openwrt_one-snand-preloader.bin
  • openwrt-mediatek-filogic-openwrt_one-factory.ubi

Then to flash:

• Switch boot selector on the back from NAND to NOR
• Power on the device
• Wait until the front leds turn on (all three)
• Hold front key for a couple of seconds, until only the white LED is on
• Wait for the flashing to finish, green LED will turn on
• Remove power, switch boot selector back to NAND

Flashing NVME:

Now the NVME can be flashed, also from USB.

• Format a USB stick with a single FAT partition
• Download:
  • the system image (e.g. openwrt.img.zst)
  • the associated bmap file (e.g. openwrt.img.bmap)

For flashing the recovery image should be booted from NAND:

• Power on the device
• On first boot Bad EC magic messages can be shown, this can be ignored
• If there was no OS on the NVME, the system will automatically boot the recovery image. Otherwise stop U-Boot and execute run boot_recovery
• On boot a small flasher UI will show up on serial console.
• Simply select an image to flash (detected on USB drive)
• Once flashing is done, hit enter to reboot into the Debian system!
• On first boot systemd-firstboot will prompt for hostname, root shell, root password. Be aware the boot messages can somewhat hide it prompting to start.
• Have fun!

Alternatively hitting Ctrl-c in the flasher will boot through to a normal login getty.

Recovery image:

The recovery image as part of the NAND image is simply a minimal Debian system running in memory. To access this system hit Ctrl-C when the flasher pops and it will boot through to a getty. Login with user root, password root. This can be used for analysing issues with the main installation. As it's a normal Debian system, apt etc will work as expected. However as it's running from memory it's all ephemeral.

Network wise all interfaces are configured to DHCP including wireless. For connect to wireless iwd is pre-installed. wlan0 is the 2.4 Ghz interface, wlan1 is 5Ghz. To connect to a wireless network:

# Get the available wireless networks
iwctl station wlan1  get-networks
# Connect to a network
iwctl station wlan1 connect <network>

System image:

The system image is a just minimal Debian system. With some basic initial tools and configuration.

• Openssh server is installed. [1]
• Hostapd with example setups for both wireless interfaces
  • By default exposed as ssid openwrt-debian with PSK: debian on openwrt one
• systemd-networkd for network configuration, by default:
  • WAN interface as DHCP
  • LAN interfaced bridge with the wireless in lanbr. Also configured to DHCP
• default leds configured via an udev rule (leds.role)
  • Green led for each ethernet interface indicates link presence
  • Amber led for each ethernet interface indicates traffic
  • White front led shows a heartbeat pattern
  • Red front led triggers on kernel panic
• Root filesystem automatically expands to fill the disk on first boot

[1]	As per debians default config root can only login via keys over ssh by default.

Reverting to OpenWrt:

As the NOR flash isn't touched, to revert to OpenWrt simply use their full recovery instructions.