Getting Android up and running on the iMX6 platform using an open source graphics stack has been impossible up until recently, but now you can. Here's a guide through the steps.

Since the hardware very much matters this is going to be divided into a few parts, the common steps and the hardware specific ones.

This post is a bit of a living document and will be changed over time, and if you have any questions about it, please reach out through email (robert.foss at collabora.com) or irc (tomeu or robertfoss on #dri-devel on freenode).

mkdir /opt/android
repo init -u https://android.googlesource.com/platform/manifest -b android-7.1.1_r28
cd /opt/android/.repo
git clone https://git.collabora.com/git/user/robertfoss/android_manifest.git local_manifests -b android-etnaviv
repo sync -j10

mkdir /opt/imx6_android
cp /opt/imx6_android
git clone https://git.collabora.com/git/user/robertfoss/linux.git -b imx_rdu2_v4.11-rc3

# The mkimage tool is used even if you're not
# using u-boot it as a bootloader
sudo apt install u-boot-tools

# Fetch Kconfig, bootloaders and some scripts
git clone https://git.collabora.com/git/user/robertfoss/rdu2.git .

# This will destroy all data on /dev/mmcblk0 and
# create boot/system/cache/data ext4 partitions 
./setup_sdcard.sh /dev/mmcblk0

# Build android, the kernel, and flash it onto an SD-card
./build_android.sh

Hardware: iMX6 Sabre

Select correct dtb file for u-boot

nano uboot_android_boot.scr

# Uncomment the correct dtb file for your platform
setenv fdt_file imx6q-sabresd.dtb
#setenv fdt_file imx6qp-sabresd.dtb

# Run build script again, to make sure boot.scr
# is created and moved to the SD-card
./build_android.sh

Start Android

The SD-card can now be put into the middlemost slot and the device can be restarted.

Hardware: RDU2

Install the bootloader

# Depending if you have a >=13" version of the RDU2
# use the imx6qp, if <13" then use the imx6q

IMX6_TYPE=imx6q
IMX6_TYPE=imx6qp
BAREBOX="zodiac/barebox-zii-${IMX6_TYPE}-rdu2.img"

# Flash bootloader to SD-card
dd if=${BAREBOX} of=/dev/mmcblk0 bs=1k
sync

# Put SD-card in the middle-most slot on the RDU2

# Install lrzsz, since it is used for a ymodem upload
sudo apt install lrzsz

# Connect to serial device /dev/ttyUSB2 and
# /dev/ttyUSB3 with minicom
# The numbering assumes the RDU2 is the only serial
# serial device connected
sudo minicom -s
    +------------------------------------------+
    | A -    Serial Device      : /dev/ttyUSB3
    | B - Lockfile Location     : /var/lock
    | C -   Callin Program      :
    | D -  Callout Program      :
    | E -    Bps/Par/Bits       : 115200 8N1
    | F - Hardware Flow Control : No
    | G - Software Flow Control : No
    |
    |    Change which setting?
    +------------------------------------------+

# Connect to Quark console on /dev/ttyUSB3
# Set boot SD-card as boot source 
#HostBoot s 0
reset

# Restart device, connect to barebox loaded just loaded
# from the SD-card on /dev/ttyUSB2
pic_setwdt 0 60
loady

# Using the minicom quickly initiate a ymodem file
# of the same barebox image you wrote to the SD-card
# Be quick, the upload will timeout after a few seconds

# Write the bootloader to SPI NOR
erase /dev/m25p0.barebox
# Depending on your RDU2 type flash one of the following
cp barebox-zii-imx6q-rdu2.img /dev/m25p0.barebox
# Or
cp barebox-zii-imx6qp-rdu2.img /dev/m25p0.barebox

# Connect to the Quark console on /dev/ttyUSB3 again
# Set SPI NOR as the boot source
#HostBoot s 2
reset

# Connect to the barebox console on /dev/ttyUSB2 again
# Edit configuration to automatically boot from mmc:
sedit /env/config
export global.boot.default=/env/boot/mmc
export global.bootm.image=/mnt/mmc1.0/android_zImage
export global.bootm.initrd=/mnt/mmc1.0/android_ramdisk.img.gz
export global.bootm.oftree=/mnt/mmc1.0/imx6qp-zii-rdu2.dtb
export global.linux.bootargs.base="console=ttymxc0,115200 console=tty0 rw rootwait ip=dhcp buildvariant=userdebug debug ignore_loglevel root=/dev/mmcblk0p2 rootfstype=ext4 rootwait init=/init printk.devkmsg=on verbose enforcing=0 androidboot.selinux=permissive drm.debug=0x00"

sedit /env/boot/mmc
#!/bin/sh
detect mmc1
mkdir -p /mnt/mmc1.0
automount -d /mnt/mmc1.0 'mount /dev/mmc1.0 /mnt/mmc1.0'
bootm

pic_setwdt 0 60     # Disable watchdog

exit

Start Android

The SD-card created in the common steps can now be put into the middlemost slot and the device can be restarted.

Thanks!

This work is built on efforts by a lot people:

• Pengutronix who's been doing i.MX6 platform work.
• Christian Gmeiner, Wladimir Van Der Laan, and the other etnviv developers.
• Rob Herring at Linaro for getting the ball rolling with AOSP for Zii.
• Andrey Smirnov for driver support for the RDU2 such as i.MX6 PCI, ARM PL310 L2 Cache controller, RTC, and other i.MX6qp driver fixups.

This post has been a part of work undertaken by my employer Collabora.

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