Intro

My media center box has recently died tragically of overheating and I decided to replace it with a brand new Cubox-4iPro. While the hardware seems pretty great, the software support is less than perfect, to say the least. Especially if you decide to put, say, Debian Testing on it instead of one of the images prepared by the vendor. Basing on these notes, I was able to install and boot the system, and had quite some fun doing so. Not everything worked as described in the notes and some tweaking needed to be done, so I present here what worked for me.

Preparing the Micro SD card and bootstrapping the system

You need to create at least two partitions: a swap and a root partition. Remember to leave some space at the beginning for the boot loader, 4MB or 8192 sectors should be more than enough. The following layout works fine for my 64GB card.

]==> fdisk /dev/mmcblk0

Command (m for help): p

Disk /dev/mmcblk0: 63.9 GB, 63864569856 bytes
255 heads, 63 sectors/track, 7764 cylinders, total 124735488 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

        Device Boot      Start         End      Blocks   Id  System
/dev/mmcblk0p1            8192     8396799     4194304   82  Linux swap / Solaris
/dev/mmcblk0p2         8396800   124735487    58169344   83  Linux

Then create the file systems and mount the root partition.

]==> mkfs.ext4 /dev/mmcblk0p2
]==> mkswap /dev/mmcblk0p1
]==> mkdir /mnt/tmp
]==> mount /dev/mmcblk0p2 /mnt/tmp/

You will need qemu-user-static and debootstrap packages to install the system on the root partition. Go here to select the appropriate kernel version.

]==> apt-get install qemu-user-static debootstrap

]==> qemu-debootstrap --foreign \
     --include=ntp,ntpdate,less,u-boot,u-boot-tools,linux-image-3.14-2-armmp,bash-completion,fake-hwclock,emacs,mc \
     --exclude=nano --arch=armhf testing /mnt/tmp http://http.debian.net/debian

Installing and setting up the boot loader

Cubox has the Initial Program Loader (IPL) in its NVRAM and you need to put the Secondary Program Loader (SPL) and the primary boot loader (Das U-Boot in our case) at the beginning of the Micro SD card.

]==> dd if=/mnt/tmp/usr/lib/u-boot/mx6_cubox-i/SPL of=/dev/mmcblk0 bs=1K seek=1
39+0 records in
39+0 records out
39936 bytes (40 kB) copied, 0.00685229 s, 5.8 MB/s

]==> dd if=/mnt/tmp/usr/lib/u-boot/mx6_cubox-i/u-boot.img of=/dev/mmcblk0 bs=1K seek=42
292+1 records in
292+1 records out
299804 bytes (300 kB) copied, 0.0451772 s, 6.6 MB/s

You will also need an appropriate DTB file and an U-Boot environment. The DTB (Device Tree Blob) is a database that represents the hardware components in the system, it is provided by the kernel package. You can get the U-Boot environment by slightly massaging the one provided by the flash-kernel package. Finally, you will need to make an environment image using mkimage command (u-boot-tools package).

]==> cp /mnt/tmp/usr/lib/linux-image-3.14-2-armmp/imx6q-cubox-i.dtb /mnt/tmp/dtb

]==> smaug# cat /mnt/tmp/root/boot.cmd

setenv device mmc
setenv partition ${mmcdev}:${mmcpart}
setenv bootargs 'root=/dev/mmcblk0p2 rootfstype=ext4 rootwait console=ttymxc0,115200n8 console=tty1'

image_locations='/boot/ /'
for pathprefix in ${image_locations}
do
  load ${device} ${partition} ${loadaddr} ${pathprefix}vmlinuz \
  && load ${device} ${partition} ${fdt_addr} ${pathprefix}dtb \
  && load ${device} ${partition} ${ramdiskaddr} ${pathprefix}initrd.img \
  && echo "Booting Debian ${kvers} from ${device} ${partition}..." \
  && bootz ${loadaddr} ${ramdiskaddr}:${filesize} ${fdt_addr}
done

]==> mkimage -A arm -O linux -T script -C none -n "Initial u-boot script" -d /mnt/tmp/root/boot.cmd /mnt/tmp/boot/boot.scr
Image Name:   Initial u-boot script
Created:      Tue Aug 12 22:59:31 2014
Image Type:   ARM Linux Script (uncompressed)
Data Size:    576 Bytes = 0.56 kB = 0.00 MB
Load Address: 00000000
Entry Point:  00000000
Contents:
   Image 0: 568 Bytes = 0.55 kB = 0.00 MB

Applying basic settings

Before you can boot into the system, you need to provide the file system information, root password, console settings, host name, apt sources and such.

]==> cat /mnt/tmp/etc/fstab
/dev/mmcblk0p2 /               ext4    errors=remount-ro 0       1
/dev/mmcblk0p1 none            swap    defaults          0       0
]==> chroot /mnt/tmp passwd root
]==> echo 'T0:23:respawn:/sbin/getty -L ttymxc0 115200 vt100' >> /mnt/tmp/etc/inittab
]==> echo 'cubox' > /mnt/tmp/etc/hostname
]==> cat /mnt/tmp/etc/apt/sources.list
deb http://security.debian.org/ testing/updates main contrib non-free
deb-src http://security.debian.org/ testing/updates main contrib non-free

deb http://ftp2.fr.debian.org/debian// testing-updates main contrib non-free
deb-src http://ftp2.fr.debian.org/debian/ testing-updates main contrib non-free

deb http://ftp2.fr.debian.org/debian testing main contrib non-free
deb-src http://ftp2.fr.debian.org/debian testing main contrib non-free

The system does not have a real time clock, but you can cheat and preserve the time at least between reboots with good enough accuracy. To do this you can, for instance, set the current time to the last modification time of /var/log/syslog as early in the boot sequence as possible. Download this script and put it in /mnt/tmp/etc/init.d then run:

]==> chmod 755 /etc/init.d/rtcemu
]==> chroot /mnt/tmp /bin/bash
]==> update-rc.d rtcemu defaults
]==> touch /var/log/syslog

Serial console

As of writing this, the HDMI output does not really work out of the box, so you will need to access the serial console to boot into the system and make it accessible over the network. You can use a Micro USB cable and screen for this purpose, like this:

]==> screen /dev/ttyUSB0 115200

Booting

You are now ready to boot the box. Insert the Micro SD card, attach the power cable and see the system boot in your screen session. When it starts the boot count-down, stop it by pressing enter and type the following:

setenv mmcpart 2
saveenv
boot

Doing this changes the boot partition to 2 and saves the environment on the card so that you won't have to re-do this every time you reboot the system.

Post-boot settings

Now you need to configure the network, set up time zones, locale settings, keyboard layout and install some useful packages, like network-manager and openssh-server.

]==> dhclient eth0
]==> dpkg-reconfigure tzdata
]==> apt-get update
]==> apt-get install console-data keyboard-configuration locales
]==> dpkg-reconfigure console-data
]==> dpkg-reconfigure keyboard-configuration
]==> dpkg-reconfigure locales
]==> service keyboard-setup restart
]==> apt-get install network-manager openssh-server
]==> update-rc.d network-manager defaults
]==> update-rc.d ssh defaults

flash-kernel is an utility that can hook into dpkg and make the newly installed kernels visible to U-Boot.

]==> apt-get install flash-kernel
]==> cat /etc/default/flash-kernel
LINUX_KERNEL_CMDLINE="root=/dev/mmcblk0p2 rootfstype=ext4 rootwait console=ttymxc0,115200n8 console=tty1"

You have an operational base system now!

What's next?

So, what is next? Plenty of fun! :) The device needs a kernel that can leverage all its features and then xserver and xbmc, it's supposed to be a media center box after all. Stay tuned.