A while back I got an Odroid U3 , an ARM based single board computer, much like the Raspberry PI, only a lot more powerful - the Odroid U3, has a quad core 1.7GHz ARM CPU and 2GB RAM.

However only images for xubuntu are provided officially, being an openSUSE user I wanted to run openSUSE on the Odroid U3. I managed to hack together an image a few months back, but sadly didn't really document how I did it, rather silly of me.

The basic approach is to hack together an image, from the xubuntu Odroid U3 images and the openSUSE JEOS root file system images. This allows the use of the Odroid U3 customised kernels with an openSUSE based user space. We can then use the Odroid U3 kernel updating script once our image boots to get the latest kernel images.

To build our image, we are going to need a machine, with a few gigs of free space to be able to assemble and then copy the image over. You will also need a USB micro-SD card reader to be able to copy the image to the card.

All steps should be executed as root!

First we need to download some stuff that we need to build our franken-image:

buildhost:~ # wget http://dn.odroid.com/4412/Linux/ubuntu-u2-u3/xubuntu-13.10-desktop-armhf_odroidu_20140211.img.xz
buildhost:~ # xz -d xubuntu-13.10-desktop-armhf_odroidu_20140211.img.xz
buildhost:~ # wget http://download.opensuse.org/ports/armv7hl/distribution/13.1/appliances/openSUSE-13.1-ARM-JeOS.armv7-rootfs.armv7l-1.12.1-Build33.1.tbz
buildhost:~ # wget http://builder.mdrjr.net/tools/boot.scr_opensuse.tar
buildhost:~ # wget http://builder.mdrjr.net/tools/kernel-update.sh
buildhost:~ # wget http://builder.mdrjr.net/kernel-3.8/00-LATEST/odroidu2.tar.xz
buildhost:~ # wget http://builder.mdrjr.net/tools/firmware.tar.xz
buildhost:~ # xz -d odroidu2.tar.xz
buildhost:~ # xz -d firmware.tar.xz

Now take a copy of the xubuntu image, this will form the basis for our custom image. By starting with a working image, we have the partitioning and bootloader already installed. As I understand it, the first 1MiB of the image is taken up by the phase one bootloader and the position of partitions is important. The phase one bootloader will read boot.scr from the vfat partition which then loads the zImage (compressed kernel).

buildhost:~ # cp xubuntu-13.10-desktop-armhf_odroidu_20140211.img custom_opensuse.img

Next we need to ensure that the loop device module is loaded.

buildhost:~ # modprobe loop.

Now we can mount our image.

buildhost:~ # losetup /dev/loop0 custom_opensuse.img
buildhost:~ # kpartx -a /dev/loop0
buildhost:~ # mkdir tmp_boot
buildhost:~ # mkdir tmp_root
buildhost:~ # mount /dev/mapper/loop0p1 tmp_boot
buildhost:~ # mount /dev/mapper/loop0p2 tmp_root

Now empty out the entire root file system, we are going to replace that with the openSUSE root file system. We will then patch in the latest kernels.

buildhost:~ # cd tmp_root
buildhost:~/tmp_root # rm -rf *

Now extract the openSUSE root file system into our image

buildhost:~/tmp_root # tar -xjf ~/openSUSE-13.1-ARM-JeOS.armv7-rootfs.armv7l-1.12.1-Build33.1.tbz

Now we can patch in the odroid kernel

buildhost:~/tmp_root # cd boot
buildhost:~/tmp_root/boot # cp ../../boot.scr_opensuse.tar ./
buildhost:~/tmp_root/boot # tar -xvf boot.scr_opensuse.tar
buildhost:~/tmp_root/boot # rm boot.scr_opensuse.tar
buildhost:~/tmp_root/boot # rm -rvf x
buildhost:~/tmp_root/boot # mv x2u2/* ./
buildhost:~/tmp_root/boot # rm -rvf x2u2
buildhost:~/tmp_root/boot # cp boot-hdmi-720p60hz.scr boot.scr
buildhost:~/tmp_root/boot # cd ..
buildhost:~/tmp_root # cd lib/modules
buildhost:~/tmp_root/lib/modules # rm -rf *
buildhost:~/tmp_root/lib/modules # cd ../..
buildhost:~/tmp_root # cp ../odroidu2.tar ./
buildhost:~/tmp_root # tar -xvf odroidu2.tar
buildhost:~/tmp_root # rm odroidu2.tar
buildhost:~/tmp_root # cd lib/firmware
buildhost:~/tmp_root/lib/firmware # rm -rf *
buildhost:~/tmp_root/lib/firmware # cp ../../../firmware.tar.xz ./
buildhost:~/tmp_root/lib/firmware # tar -xvf firmware.tar.xz
buildhost:~/tmp_root/lib/firmware # rm firmware.tar.xz
buildhost:~/tmp_root/lib/firmware # cd ../../..
buildhost:~ # cd tmp_boot
buildhost:~/tmp_boot # rm -rvf *
buildhost:~/tmp_boot # cp ../tmp_root/boot/* ./

Now we need to setup fstab, edit ~/tmp_root/etc/fstab to have the following contents:

devpts  /dev/pts          devpts  mode=0620,gid=5 0 0
proc    /proc             proc    defaults        0 0
sysfs   /sys              sysfs   noauto          0 0
debugfs /sys/kernel/debug debugfs noauto          0 0
usbfs   /proc/bus/usb     usbfs   noauto          0 0
tmpfs   /run              tmpfs   noauto          0 0
UUID=e139ce78-9841-40fe-8823-96a304a09859 / ext4 defaults 0 0
/dev/mmcblk0p1 /boot vfat defaults 0 0

Note: use blkid to check the UUID of the root fs (/dev/mapper/loop0p2) is e139ce78-9841-40fe-8823-96a304a09859

Now lets make some changes to the systemd journal config, edit ~/tmp_root/etc/systemd/journald.conf change the following variables:

Storage=volatile
ForwardToConsole=yes
TTYPath=/dev/tty12

This allows us to see the journal on TTY 12 ( CTRL-ALT-F12) which is handy for debugging, it also doesn't store the journal on disk (as SD cards can be horrifically slow).

Now we need to make some changes to the systemd config:

buildhost:~/tmp_root # cd etc/systemd/system
buildhost:~/tmp_root/etc/systemd/system # cd default.target.wants
buildhost:~/tmp_root/etc/systemd/system/default.target.wants # rm -rvf *
buildhost:~/tmp_root/etc/systemd/system/default.target.wants # cd ..
buildhost:~/tmp_root/etc/systemd/system # cd multi-user.target.wants
buildhost:~/tmp_root/etc/systemd/system/multi-user.target.wants # rm -f wpa_supplicant.service
buildhost:~/tmp_root/etc/systemd/system/multi-user.target.wants # rm -f remote-fs.target
buildhost:~/tmp_root/etc/systemd/system/multi-user.target.wants # cd ../..
buildhost:~/tmp_root/etc/systemd/ # ln -sf /usr/lib/systemd/system/multi-user.target default.target

It's handy to copy in the kernel update script:

buildhost:~/tmp_root/root # cp ../../kernel-update.sh ./
buildhost:~/tmp_root/root # chmod +x kernel-update.sh

Finally, we can unmount and flash the image

buildhost:~/ # sync
buildhost:~/ # umount tmp_root
buildhost:~/ # umount tmp_boot
buildhost:~ # kpartx -d /dev/loop0
buildhost:~ # losetup -d /dev/loop0
buildhost:~/ # dd if=./custom_opensuse.img of=/dev/sdb bs=32M

Note: make sure /dev/sdb is the SD card you want to write to, check dmesg if need be.

Nore: your liable to get odd errors from the SD card if you fail to set bs, a 32MiB block seemed the fastest for me.

Now you should be able to boot your Odroid U3 into openSUSE 13.1 (console). Once booted you can use the zypper to update any RPMs or to install a GUI. The root password is linux. Note that SSH is enabled by default.

It is worth noting, that the I/O performance of cheap SD cards is pretty terrible (or at least this is true for SD card one I have), remember to be patient.

Any issues and I can probably give you a hand in the #suse IRC channel or tweet me @intrbiz

buildhost:~/ # xz -d odroid_u3_opensuse_131.img.xz
buildhost:~/ # dd if=./odroid_u3_opensuse_131.img of=/dev/sdb bs=32M