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Installing Debian On The Turris Omnia Router

The Turris Omnia is an ARM-based (mostly) open hardware router board developed by Project Turris of CZ.NIC. It was kickstarted at Indiegogo and is available in a few shops now.

By default it runs an OpenWRT derivative called TurrisOS, but Debian armhf userland can run on it, too. For now it though needs a custom (read non-Debian) kernel as well as some additional scripts to get all the features. The custom kernel is based on some Linux 4.x branch and is maintained on Github. (Update: it is unclear if that repository is the official one. The official repository is the OpenWRT fork and has a different set of patches.)

Installing vanilla Debian

The u-boot shipped on the device does not have USB support so you will need to connect the WAN port on the device to a DHCP managed network, which you can get on your computer with NetworkManager by sharing your Internet connection.

If you are on unstable, install the debian-installer-netboot-armhf virtual package. If you don't want to install it, you can just download it with apt and then unpack it with dpkg-deb. For stretch or earlier, you can add unstable to your sources.list. If you don't want to modify your sources.list, then use a chdist or apt-venv to download it with apt and unpack it with dpkg-deb. You will need these files:

/usr/lib/debian-installer/images/9/armhf/text/debian-installer/armhf/vmlinuz
/usr/lib/debian-installer/images/9/armhf/text/debian-installer/armhf/initrd.gz
/usr/lib/debian-installer/images/9/armhf/text/debian-installer/armhf/dtbs/armada-385-turris-omnia.dtb

To enter the u-boot prompt, plug the UART to USB cable (video) into the 4 pin (black yellow red empty) header to the right of the LEDs and plug the USB end into your computer. Start your favourite serial console tool, like GNU screen, minicom or microcom, or busybox microcom and connect to the USB serial console device. The busybox microcom should already be installed on your computer if you are running Debian.

busybox microcom -s 115200 /dev/ttyUSB0
microcom -s 115200 /dev/ttyUSB0
minicom /dev/ttyUSB0
screen /dev/ttyUSB0 115200

Then power on or reset the device and hit any key to interrupt autoboot at this point:

Hit any key to stop autoboot:  3 

Then install a tftp server like tftpd-hpa on your computer, put the above files in /srv/tftp and on the serial console enter the following in U-Boot:

mw 0xf1020300 0x403 #disable watchdog
dhcp
setenv serverip <your_tftp_server_legacy_ip_address>
tftpboot 0x01000000 vmlinuz
tftpboot 0x02000000 armada-385-turris-omnia.dtb
tftpboot 0x03000000 initrd.gz
bootz 0x01000000 0x03000000:$filesize 0x02000000

If this fails for you with

Wrong Ramdisk Image Format
Ramdisk image is corrupt or invalid

your U-Boot needs an update. The U-Boot images that are about to be released by cz.nic are fixed, you can find them at https://api.turris.cz/openwrt-repo/omnia-test/nor_fw/. Update as follows after downloading the image to your tftp directory:

dhcp
tftpboot 0x1000000 uboot-turris-omnia-spl.kwb
sf probe
sf update 0x1000000 0 $filesize

Once the update is done, you will need to reboot to start the new version of U-Boot and then go back to the start of the TFTP stage above.

Once you are in the Debian Installer you will see a blue screen with a language choice (English or C). At this point you can use the standard GNU screen keys (Ctrl+a n, Ctrl+a p etc) to switch between the Debian Installer virtual terminals.

Choose English and other parameters and stop at the partitioning step to read the next paragraph. You will want to use the eth2 device for network if you have a cable connected to the WAN port.

Is possible to preserve the existing TurrisOS installation and install Debian into a subvolume of the existing btrfs filesystem on the eMMC storage. This means both TurrisOS and Debian will share the same filesystem/partition but use separate btrfs subvolumes. The Debian Installer doesn't yet support btrfs subvolumes but you can use them by switching to expert mode. When you get to the partitioning step, press tab to switch to "Go Back" and press enter. Go down to "Change debconf priority" and press enter, continue and choose "low" then go back to the partitioning step. Choose to use the btrfs volume as / but do *not* format it (a format will delete TurrisOS). After the partitioning, but before the software installation, you will need to unmount the install directory, mount the root subvolume, create a new Debian subvolume and then mount the new Debian subvolume. You can substitute @debian for any subvolume name other than @ and @factory, which are TurrisOS subvolumes.

# Check what volume is mounted
mount
# If there is something other than subvol=/ then remount
umount /target
mount -o subvol=/ /dev/mmcblk0p1 /target
# Create the Debian subvolume
btrfs subvolume create /target/@debian
# move all non-subvolume files/dirs to the Debian subvolume
# Anything with @ in the name is likely a subvolume
mv /target/etc /target/media /target/@debian
# Remount with the Debian subvolume
umount /target
mount -o subvol=@debian /dev/mmcblk0p1 /target

Before ending the installation switch back to a shell, add the Debian subvolume to the rootfs mount options and put the dtb into the Debian rootfs as /target/boot/dtb.

chroot /target sed -i s/defaults/defaults,subvol=@debian/ /etc/fstab
cp /sys/firmware/fdt /target/boot/dtb

After the installation, reboot into the uboot prompt. At this point you need to create a command to boot Debian.

To create the command to boot Debian and then run it:

setenv debbootargs earlyprintk console=ttyS0,115200 rootfstype=btrfs rootwait root=/dev/mmcblk0p1 rootflags=subvol=@debian,commit=5 rw
setenv debboot 'setenv bootargs "$debbootargs cfg80211.freg=$regdomain"; btrload mmc 0 0x01000000 boot/vmlinuz @debian; btrload mmc 0 0x02000000 boot/dtb @debian; btrload mmc 0 0x03000000 boot/initrd.img @debian; bootz 0x01000000 0x03000000:$filesize 0x02000000'
saveenv

You can then set the default to boot from Debian, but run TurrisOS in rescue mode 1 (aka LED 5) (normal rescue mode moves to rescue mode 2 (aka LED 6)).

# Save the default bootcmd for a backup
# in case you want to revert to defaults.
setenv defbootcmd "$bootcmd"
# Add Debian to the boot command by default and relegate TurrisOS to rescue mode 1
setenv bootcmd 'i2c dev 1; i2c read 0x2a 0x9 1 0x00FFFFF0; setexpr.b rescue *0x00FFFFF0; if test $rescue -ge 2; then echo BOOT RESCUE; run rescueboot; elif test $rescue -ge 1; echo BOOT eMMC TurrisOS FS; run mmcboot; else echo BOOT eMMC Debian FS; run debboot; fi; fi'
saveenv

There are some missing parts yet, so the SFP and switch port doesn't work. With the Debian kernel the wifi driver fails to probe, while this works with a monolithic (vanilla) kernel compiled for mvebu + ath10k.

Watchdog handling

The bootloader enables the watchdog of the SoC. To handle this you either have to disable it again in the bootloader (see above) or pet it regularly. For the latter just add

[Manager]
RuntimeWatchdogSec=10s

to /etc/systemd/system.conf.

MAC address

U-Boot doesn't provide the mac addresses to be used in the device tree. To make the Debian system use the right ones I did:

cat > /etc/systemd/network/00-eth0.link
[Match]
Path=platform-f1070000.ethernet
[Link]
MACAddress=...
EOF

and the same for eth1 (platform-f1030000.ethernet) and eth2 (platform-f1034000.ethernet).

The mac address reserved for your machine is saved in the crypto chip. To find out the base check U-Boot's ethaddr variable. You "own" this and the two following addresses.

RTC

The in-SoC RTC isn't working properly. It is somewhat working after doing

mw 0xf10184a0 0xfd4d4cfa

in U-Boot. If you don't do this, the driver only reads 2016-12-19 22:00:34 from it.

Wifi

The Debian kernel fails to probe the wifi drivers. There is already a bug report about this. As a work around add

pcie_aspm=off

on the kernel command line, then the wifi drivers probe correctly.

Installing with self-build kernel

For an alternative installation using a self compiled kernel (instead of a debian kernel as above) see the omnia-debian wiki. If you follow this one, you're not keen on cross-compiling and accept to trust images downloaded unencrypted from the internet, you can find an ready-made image on http://aule.elfove.cz/%7Ebrill/omnia-debian/.

Default uboot env

baudrate=115200
bootargs=earlyprintk console=ttyS0,115200 rootfstype=btrfs rootdelay=2 root=b301 rootflags=subvol=@,commit=5 rw
bootcmd=i2c dev 1; i2c read 0x2a 0x9 1 0x00FFFFF0; setexpr.b rescue *0x00FFFFF0; if test $rescue -ge 1; then echo BOOT RESCUE; run rescueboot; else echo BOOT eMMC FS; run mmcboot; fi
bootdelay=3
ethact=neta2
ethaddr=d8:58:d7:XX:XX:XX
fdt_high=0x10000000
initrd_high=0x10000000
mmcboot=setenv bootargs "$bootargs cfg80211.freg=$regdomain"; btrload mmc 0 0x01000000 boot/zImage @; btrload mmc 0 0x02000000 boot/dtb @; bootz 0x01000000 - 0x02000000
regdomain=**
rescueboot=i2c mw 0x2a.1 0x3 0x1c 1; i2c mw 0x2a.1 0x4 0x1c 1; mw.l 0x01000000 0x00ff000c; i2c write 0x01000000 0x2a.1 0x5 4 -s; setenv bootargs "$bootargs omniarescue=$rescue"; sf probe; sf read 0x1000000 0x100000 0x700000; bootz 0x1000000
stderr=serial@12000
stdin=serial@12000
stdout=serial@12000

See also