VAR-SOM-MX6 Android

From Variscite Wiki
VAR-SOM-MX6 - Android Nougat N7.1.1 Developer Guide


This Wiki describes how to build and deploy Android Nougat on the VAR-SOM-MX6. It is based on NXP's IMX6_N7.1.1_1.0.0_ANDROID release


The objective of this document is to guide VAR-SOM-MX6 Android developers to obtain Android Nougat sources, setting up host environment, compilation, and deployment.

This document contains instructions for:

  • Hardware and software requirements.
  • Setup the hardware.
  • Setup the toolchain.
  • Download & build the sources.
  • Install the binaries on the VAR-SOM-MX6 SOM and variants.

Supported hardware and features

SOM support
Carrier Board support

i.MX6 Quad Plus
i.MX6 Quad
i.MX6 Dual
i.MX6 Dual lite
i.MX6 Solo

NAND flash size support
128MB and up
up to 64GB
DDR size support configuration
Solo:up to 1GB. DualLite, Dual, Quad: up to 4GB
SD card
Wired Network
10/100/1000 Mbps Ethernet
Wireless Network
Support for Wilink8, 802.11abgn STA, AP, & Wi-Fi Direct Mode SmartConfig Wilink8 page
USB host
Host and Device
x3, up to 3.6 Mbps.
Display HDMI: 720P,1080P
LVDS0 (On board LVDS-to-RGB bridge, 800x480 resolution), LVDS1 external display
Audio Line IN/ Line out and Audio over HDMI
Camera OV5640 camera sensor (VAR-EXT-CB402 camera board can be ordered separately)

Hardware Requirements

  • You will need the Variscite VAR-SOM-MX6 based evaluation kit.
  • Debug UART cable - For serial Debugging
  • OTG Micro B to A - For adb and fastboot

Host (PC) setup requirements

The host development environment for Android is based on Ubuntu and Debian, please install Ubuntu version 14.04/16.04 64bit LTS or Debian 8.4 64bit

We recommend to have Physical Build machine, but if you are running Linux in a virtual machine, please make sure you allocate at least 16GB of RAM and 32 GB swap to virtual machine.

Note: Do not use other Ubuntu or Debian releases, than the ones recommended above.

Install required packages on host PC

$ sudo apt-get -y install git-core gnupg flex bison gperf build-essential zip curl zlib1g-dev gcc-multilib g++-multilib \
libc6-dev-i386 lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z-dev ccache libgl1-mesa-dev libxml2-utils xsltproc \
unzip mtd-utils u-boot-tools lzop liblzo2-2 liblzo2-dev zlib1g-dev liblz-dev uuid uuid-dev android-tools-fsutils bc

If you are using Ubuntu 16.04 LTS latest repo tool requires Python 3.0

$ sudo add-apt-repository ppa:deadsnakes/ppa
$ sudo apt-get install python3.6
$ sudo apt-get install python-is-python2

If you are using Ubuntu 20.04 LTS requires below package

$ sudo apt-get install python-is-python2

Configure GIT account

$ git config --global "Your Name"
$ git config --global "Your Email"

Install the OpenJDK

Android Nougat requires OpenJDK 8.

To install it:

$ sudo apt-get update
$ sudo apt-get install openjdk-8-jdk

If your Ubuntu version is missing the package (which shouldn't happen), add the PPA repository and run the previous commands again:

$ sudo add-apt-repository ppa:openjdk-r/ppa

Update the default Java version by running:

$ sudo update-alternatives --config java
$ sudo update-alternatives --config javac

Note: The build process requires about 135GB of free space.

Obtain source code

Variscite's Linux kernel and U-Boot are available through Github.
Required patches for the Android file system are under: in Variscite's FTP


  • android_N7.1.1_1.0.0_source.tar.gz - NXP's i.MX6 N7.1.1_1.0.0 original BSP patch files.

Get NXP's Android Release Package

$ mkdir ~/var_n_711_100
$ cd ~/var_n_711_100
$ curl -o ~/Downloads/android_N7.1.1_1.0.0_source.tar.gz
$ tar xvf ~/Downloads/android_N7.1.1_1.0.0_source.tar.gz

Download Google Android N7.1.1

$ mkdir -p ~/bin
$ curl -o ~/bin/repo
$ chmod a+x ~/bin/repo
$ export PATH=~/bin:$PATH
$ mkdir ~/var_n_711_100/n_711_100_build
$ cd  ~/var_n_711_100/n_711_100_build
$ repo init -u -b android-7.1.1_r13
$ repo sync -j4

Clone Variscite's U-Boot and Linux kernel sources

$ mkdir -p ~/var_n_711_100/n_711_100_build/bootable/bootloader
$ cd ~/var_n_711_100/n_711_100_build/bootable/bootloader
$ git clone -b n7.1.1_1.0.0_ga_var01
$ cd ~/var_n_711_100/n_711_100_build
$ git clone kernel_imx -b n7.1.1_1.0.0-ga-var01

Apply all the i.MX Android patches with Freescale i.MX6 support

$ cd ~/var_n_711_100/n_711_100_build
$ source ../android_N7.1.1_1.0.0_source/code/N7.1.1_1.0.0/
**** Invoke "." from your shell to add following functions to your environment:
****-- c_gotop:     Changes directory to the top of the tree 
****-- c_patch:     Recover working tree to base version and then applying FSL android patch

$ c_patch  ../android_N7.1.1_1.0.0_source/code/N7.1.1_1.0.0 imx_N7.1.1_1.0.0
If everything is OK, "c_patch" generates the following output to indicate the successful patch:
Success: Now you can build android code for FSL i.MX platform

Apply Variscite's i.MX6 platforms' patches

$ cd ~/var_n_711_100/n_711_100_build/device
$ git clone -b n7.1.1_1.0.0-ga-var01 variscite
$ variscite/scripts/

Build Android Images

Change to Android top level directory.

$ cd ~/var_n_711_100/n_711_100_build
$ source build/
$ lunch var_mx6-eng
$ lunch var_mx6-user

Note: var_mx6-user creates a production version of Android. var_mx6-eng creates an engineering version of Android. Development mode enable and development tools are available on target.

$ export PATH=/usr/lib/jvm/java-8-openjdk-amd64/bin:$PATH

Switching from eMMC build to SD card build and vice versa

When you switch your target MMC device you need to remove the fstab file. This will guarantee that the make system will copy the right one into target.

$ rm out/target/product/var_mx6/recovery/root/fstab* out/target/product/var_mx6/root/fstab*

Build Android for SD card

$ make -j4 BUILD_TARGET_DEVICE=sd 2>&1 | tee build1-1.log
  • Note: When running Android from an SD card, the eMMC will be detected and presented as an SD card storage.

Build Android for on-SOM eMMC

$ make -j4 BUILD_TARGET_DEVICE=emmc 2>&1 | tee build1-1.log

Special notes for DART-MX6: user builds for eMMC

Due to HW specific features, dm-verity feature has been disabled on user builds for eMMC on DART-MX6.

To enable this feature, follow next steps:

  • correctly set PRODUCT_SYSTEM_VERITY_PARTITION in device/variscite/imx6/
  • enable verify in device/variscite/var_mx6/fstab_emmc_dart.freescale

The comments in the files will suggest the detailed actions.

Build for NAND

Note: Due to android file system size, Android should use SD card or eMMC only

Images created by the Android build for Variscite MX6 system

If you do ls out/target/product/var_mx6/

system.img Android system image file.
SOM agnostics.
u-boot-var-imx6-nand.img U-Boot for nand used in eMMC boot.
SOM agnostics.
u-boot-var-imx6-sd.img U-Boot for SD card boot.
SOM agnostics.
<name> is one of: som-mx6q - Supports VAR-SOM-MX6Q and VAR-SOM-MX6D
som-mx6dl - Supports VAR-SOM-MX6DL and VAR-SOM-MX6S
som-solo - Supports VAR-SOM-SOLO and VAR-SOM-DUAL
<touch> - is "r" or "c" r = resistive touch display
c = capacitive touch dispaly
Setup Name
Images Names
SOM type
Carrier Board type
LCD Type
Evaluation Kit name
som-mx6qp-c boot-som-mx6qp-c.img,
VAR-SOM-MX6_V2 (Quad Plus) VAR-MX6CustomBoard Capacitive touch VAR-DVK-MX6_V2-PRO,
som-mx6qp-r boot-som-mx6qp-r.img,
VAR-SOM-MX6_V2 (Quad Plus) VAR-MX6CustomBoard Resistive touch VAR-DVK-MX6_V2,
som-mx6qp-vsc boot-som-mx6qp-vsc.img,
VAR-SOM-MX6_V2 (Quad Plus) VAR-SOLOCustomBoard Capacitive LVDS touch N/A
som-mx6q-c boot-som-mx6q-c.img,
VAR-SOM-MX6_V2 (Quad / Dual) VAR-MX6CustomBoard Capacitive touch VAR-DVK-MX6_V2-PRO,
som-mx6q-r boot-som-mx6q-r.img,
VAR-SOM-MX6_V2 (Quad / Dual) VAR-MX6CustomBoard Resistive touch VAR-DVK-MX6_V2,
som-mx6q-vsc boot-som-mx6q-vsc.img,
VAR-SOM-MX6_V2 (Quad / Dual) VAR-SOLOCustomBoard Capacitive LVDS touch N/A
som-mx6dl-c boot-som-mx6dl-c.img,
VAR-SOM-MX6_V2 (DualLite/ Solo) VAR-MX6CustomBoard Capacitive touch N/A
som-mx6dl-r boot-som-mx6dl-r.img,
VAR-SOM-MX6_V2 (DualLite/ Solo) VAR-MX6CustomBoard Resistive touch N/A
som-solo-vsc boot-som-solo-vsc.img,
som-solo-c boot-som-solo-c.img,
VAR-SOM-SOLO / VAR-SOM-DUAL VAR-MX6CustomBoard Capacitive touch N/A
imx6q-var-dart boot-imx6q-var-dart.img,
DART-MX6 VAR-DT6CustomBoard Capacitive touch VAR-STK-DT6,

Boot options

The Android boot options are:
1. Directly from an SD card
2. U-Boot boots from NAND flash, and the rest of the Android images from the on-SOM eMMC (when available)

Flash and boot Android from SD card

Create a bootable SD card

Partition and format SD card, and copy all images

$ sudo ./ -f SETUP_NAME /dev/sdX;sync
  • Replace SETUP_NAME with the actual desired setup name accrding to the second table in the "images created" section.
  • Replace /dev/sdX with your true device, You can identify it with dmesg.

Boot From SD card

  • Power-off the board.
  • Insert the SD card into the SD card slot of the carrier board (DVK)
  • Make sure the Boot Mode is set to SD card: see Setting the Boot Mode section
  • Power up the board - it will boot into Linux from the SD card

Flash and boot Android from eMMC

eMMC based system consist of:

  1. SPL and U-Boot on NAND flash
  2. Rest of Android images in eMMC

Preparing images

All Android built images but system.img are ready for flashing out of the default build.

The default system.img format is suitable for flashing using fastboot, and must be modified for flashing using 'dd'.

$ cd out/target/product/var_mx6
$ simg2img system.img system_raw.img

Make sure you built Android for eMMC

Flashing Android from Linux shell (when the primary installation android)

An example of flashing eMMC, can be found here.

Follow the following steps instructions above:

1. Preparing a rescue SD card;

2. Flash from command line (use the script)

Further, follow the steps described in paragraph "Flashing Android with USB Fastboot"

Flashing Android with USB Fastboot

Install tools on host

$ sudo apt-get install android-tools-adb android-tools-fastboot

Note: Make sure you built Android for eMMC
Connect the target with host PC at fastboot mode:

  1. Connect a USB OTG cable from the target board OTG port to a your host machine USB HOST port.
  2. Power up the board and hit return/space to stop the boot at U-Boot.
  3. type fastboot usb0 in the U-Boot command line.

On the Host PC:

$ sudo `which fastboot` flash boot out/target/product/var_mx6/boot-SETUP_NAME.img
$ sudo `which fastboot` flash recovery out/target/product/var_mx6/recovery-SETUP_NAME.img
$ sudo `which fastboot` flash system out/target/product/var_mx6/system.img
$ sudo `which fastboot` reboot

Replace SETUP_NAME with the actual desired setup name accrding to the second table in the "images created" section.

Android recovery mode

Enter board in Android Recovery mode

Turn on the device by holding down the "back" button must be held until the end of the boot and logged in "Android Recovery" mode.

Control menu in Android Recovery Mode

  1. To switch between menu items, use a short press of any button (except RESET) or a short touch touchscreen;
  2. To select an item, use long press any button (except RESET) or long touch the touchscreen;

Update Android firmware

Generate OTA packages For generating "OTA" packages, use the following commands:

$ cd ~/var_n_711_100/n_711_100_build
# if Android for SD card
$ make -j4 BUILD_TARGET_DEVICE=sd otapackage 2>&1 | tee build1-1.log
# if Android for eMMC
$ make -j4 BUILD_TARGET_DEVICE=emmc otapackage 2>&1 | tee build1-1.log

Install OTA package to device

  1. Enter to Android Recovery mode
  2. Select menu item "apply update from ADB"
  3. To the host system, perform the following command:
    $ out/host/linux-x86/bin/adb sideload out/target/product/var_mx6/var_mx6-ota-<data>-<image-id>.zip
  4. reboot this device

Note: Real example name for OTA package: out/target/product/var_mx6/

Manual operations

Build boot.img

When you perform changes to the kernel, you may build boot.img solely instead of building the whole Android.

$ cd ~/var_n_711_100/n_711_100_build 
$ source build/
$ lunch var_mx6-eng
$ lunch var_mx6-user
$ make bootimage

Toolchain setup for manual build kernel and U-Boot

$ export ARCH=arm
Setup the toolchain path to point to arm-eabi- tools in prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin
$ export CROSS_COMPILE=~/var_n_711_100/n_711_100_build/prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-

Manual build Bootloader 

Change directory to U-Boot

$ cd ~/var_n_711_100/n_711_100_build/bootable/bootloader/uboot-imx

Execute following commands:

clean tree:
$ make mrproper

Choose build for SD card or NAND flash:
$ make mx6var_som_sd_android_defconfig
$ make mx6var_som_nand_android_defconfig

Build U-Boot:
$ make -j4

This command will generate the U-Boot images 'SPL' and 'u-boot.img'.

Manual build Android Linux Kernel and modules

$ cd ~/var_n_711_100/n_711_100_build/kernel_imx
$ make mrproper
$ make imx_v7_var_android_defconfig
$ make -j4
$ make -j4 uImage LOADADDR=0x10008000

This will generate the uImage (kernel image) in the kernel/arch/arm/boot folder