DART-6UL Yocto Krogoth R1 build

From Variscite Wiki
DART-6UL - Yocto fsl-4.1.15 Yocto Krogoth R1 Build

1 Installing required packages

Follow the link below and install all required packages on your machine.


Please make sure you host PC is running Ubuntu 14.04 and install the following packages:

sudo apt-get install gawk wget git-core diffstat unzip texinfo gcc-multilib build-essential chrpath socat libsdl1.2-dev
sudo apt-get install autoconf libtool libglib2.0-dev libarchive-dev
sudo apt-get install python-git xterm sed cvs subversion coreutils texi2html
sudo apt-get install docbook-utils python-pysqlite2 help2man make gcc g++ desktop-file-utils libgl1-mesa-dev
sudo apt-get install libglu1-mesa-dev mercurial automake groff curl lzop asciidoc u-boot-tools dos2unix mtd-utils
sudo apt-get install pv

2 Documentation

Documentation are available for Download from FreescaleKrogothDocuments

3 Download Yocto Krogoth for i.MX Freescale source

$ git config --global user.name "Your Name"
$ git config --global user.email "Your Email"

$ mkdir ~/bin (this step may not be needed if the bin folder already exists)
$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
$ export PATH=~/bin:$PATH

$ mkdir ~/var-imx-yocto-krogoth
$ cd ~/var-imx-yocto-krogoth
$ repo init -u https://github.com/varigit/variscite-bsp-platform -b krogoth -m imx-4.1-krogoth_r1
$ repo sync -j4

4 Setup and build Yocto

The following distros can be used:

  • fsl-imx-x11 - Only X11 graphics
  • fsl-imx-wayland - Wayland weston graphics
  • fsl-imx-xwayland - Wayland graphics and X11. X11 applications using EGL are not supported
  • fsl-imx-fb - Frame Buffer graphics - no X11 or Wayland

Note: refer to ftp://customerv:Variscite1@ftp.variscite.com/VAR-SOM-MX6/Software/Linux/Yocto/fsl-yocto-imx-4.1.15_2.0.0-docs/i.MX_Yocto_Project_User's_Guide.pdf
Chapter 5 for further information.

Sample build scenarios:

4.1 Build X11 GUI image without Qt content

$ cd ~/var-imx-yocto-krogoth
$ MACHINE=imx6ul-var-dart DISTRO=fsl-imx-x11 source var-setup-release.sh -b build_x11

Optional steps: local.conf customization

launch bitbake:

$ bitbake fsl-image-gui

4.2 Build Qt5 image without X11

$ cd ~/var-imx-yocto-krogoth
$ MACHINE=imx6ul-var-dart DISTRO=fsl-imx-fb source var-setup-release.sh -b build_fb

Optional steps: local.conf customization

launch bitbake:

$ bitbake fsl-image-qt5

4.3 local.conf customization

4.3.1 Change the downloads directory

Create a /opt/yocto_downloads directory and set its permissions:

$ sudo mkdir /opt/yocto_downloads
$ sudo chmod 777 /opt/yocto_downloads/

Direct downloads to it, by replacing 'DL_DIR ?= "${BSPDIR}/downloads/"' with 'DL_DIR = "/opt/yocto_downloads/"' in conf/local.conf:

$ sed -i 's/DL_DIR ?= "${BSPDIR}\/downloads/DL_DIR = "\/opt\/yocto_downloads/g' conf/local.conf

4.3.2 Add Eclipse debug and Qt creator support to your images

Append the following to the conf/local.conf file in your Yocto build directory, to add Eclipse debug and Qt creator support to your images:

    debug-tweaks \
    tools-debug \
    eclipse-debug \

IMAGE_INSTALL_append = " \
    tcf-agent \
    openssh-sftp-server \

4.3.3 Use systemd instead of SysV init

Append the following to the conf/local.conf file in your Yocto build directory, to use systemd instead of SysV init in your images:

DISTRO_FEATURES_append = " systemd"
VIRTUAL-RUNTIME_init_manager = "systemd"
VIRTUAL-RUNTIME_initscripts = ""

4.4 Build Results

The resulted images are located at tmp/deploy/images/imx6ul-var-dart:

File Name Description
fsl-image-gui-imx6ul-var-dart.sdcard This image is for SD card boot.
It can be flashed as-is on an SD card that can then be used to boot your system.
For detailed information refer to the Create a bootable SD card section below.
fsl-image-gui-imx6ul-var-dart.tar.bz2 Tarball with rootfs files.
Can be used to create an NFS root file system on the host.
See the Setup TFTP/NFS Yocto system section for more info.
Also used to create our extended SD card.
See the Create a bootable SD card section below.
fsl-image-gui-imx6ul-var-dart.ubi A complete UBI image containing a UBIFS volume, for writing to NAND flash.
zImage Linux kernel image, same binary for SD card/eMMC/NAND flash.
SPL-nand SPL built for NAND flash. The SPL is a pre-U-Boot SW component, used for DDR initialization
SPL-sd SPL built for SD card boot. The SPL is pre-U-Boot SW component, used for DDR initialization
u-boot.img-sd U-Boot built for SD card/eMMC.
u-boot.img-nand U-Boot built for NAND flash.
zImage-imx6ul-var-dart-emmc_wifi.dtb Device tree blob with eMMC & WI-FI enabled. (SD card & NAND disabled)
zImage-imx6ul-var-dart-nand_wifi.dtb Device tree blob with NAND flash & WI-FI enabled. (SD card & eMMC disabled)
zImage-imx6ul-var-dart-sd_emmc.dtb Device tree blob with SD card & eMMC enabled (WIFI & NAND disabled)
zImage-imx6ul-var-dart-sd_nand.dtb Device tree blob with SD card & NAND flash enabled (WIFI & eMMC disabled)

5 Create a bootable SD card

5.1 SD card structure

The first unallocated 4MiB are saved for U-Boot. It can be replaced using the dd command as described in the [[DART-6UL_Yocto_Krogoth_Build_U-Boot_out_of_tree|Build U-Boot from source code] section.
The first partition is formatted with FAT16 and contains the Linux image and device tree blobs. You can copy them as described in the Build the Linux kernel from source code section.
The second partition is formatted with ext4 and contains the file system (including the kernel modules).

5.2 Yocto pre-built bootable SD card

The Yocto build products contains many files as explained in Build Results section above including a ".sdcard" file. For example, fsl-image-gui-imx6ul-var-dart.sdcard, depending on your build.
This is a complete image to be flashed directly to an SD card.
Example usage:

$ cd ~/var-imx-yocto-krogoth/build_x11
$ sudo umount /dev/sdX*
$ sudo dd if=tmp/deploy/images/imx6ul-var-dart/fsl-image-gui-imx6ul-var-dart.sdcard of=/dev/sdX bs=1M && sync
Replace sdX with the right device name.

Drawbacks of the native .sdcard yocto-built image:

  • The second partition size doesn't use the entire SD card.
  • The second partition is not labeled as rootfs.
  • The NAND and eMMC flashing scripts are not included.

5.3 Create an extended SD card

Variscite provides the var-create-yocto-sdcard.sh script which creates our NAND/eMMC recovery SD card - an SD card based on the fsl-image-gui filesystem, which copies the NAND flash burning scripts and relevant binaries for your convenience.
Later, you will be able to follow either the more automatic DART-6UL Yocto Recovery SD card guide or the more manual Flashing the internal storage device guide to burn your images to NAND flash or eMMC.

This is essentially the same as our pre-built Recovery SD image, with the following main difference:
The pre-built image's rootfs partition size is 3700MiB, which is also the default size when using the script, but the script also has an option to set the rootfs partition size to fill the whole free space of the used SD card. Anyway, you can always resize the partition later with an external tool such as gparted.
Naturally, the pre-built image is more straight forward and easier to use, while the script method is easier to customize.


  • Follow the Setup and build Yocto guide, and bitbake fsl-image-gui.
  • Plug-in the SD card to your Linux HOST PC, run dmesg and see which device is added (i.e. /dev/sdX or /dev/mmcblkX)
$ sudo MACHINE=imx6ul-var-dart ~/var-imx-yocto-krogoth/sources/meta-variscite-imx/scripts/var_mk_yocto_sdcard/var-create-yocto-sdcard.sh <options> /dev/sdX
(Replace /dev/sdX with your actual device)
  -h            Display help message
  -s            Only show partition sizes to be written, without actually write them
  -a            Automatically set the rootfs partition size to fill the SD card
  -r            Select alternative rootfs for recovery images (default: build_x11/tmp/deploy/images/imx6ul-var-dart/fsl-image-gui-imx6ul-var-dart.*)

If you don't use the '-a' option, a default rootfs size of 3700MiB will be used.
The '-r' option allows you to create a bootable SD card with an alternative image for the installation to NAND flash or eMMC.
Example: "-r tmp/deploy/images/imx6ul-var-dart/fsl-image-qt5-imx6ul-var-dart" -- selects the "Qt5 image with X11" recovery image

6 Boot board with a bootable SD card

Note: Boot from SD card eliminates Wifi as the Wifi and SD card are using same SDIO interface.
A typical use-case, is to boot from SD card, flash eMMC or NAND flash, and re-boot form eMMC/NAND to have Wi-Fi operational.

6.1 Setting the Boot DIP switches

Booting your system from an SD card requires switching the Boot DIP switches. See picture below.

Boot switch 6ul1.jpg
  • "00" The current position in the picture will set the system to boot from SD card.
  • "01" Moving the right switch will set the system to boot from eMMC
  • "10" Moving the left switch will set the system to boot from NAND flash
  • "11" is illegal.

Be aware that your system has eMMC or NAND but never both.

6.2 Automatic device Tree selection in U-Boot

Upon reset you will see the U-Boot SPL printouts. It will print also the SOM configuration:
On-SOM storage: SD only, eMMC, NAND.
WIFI if chip exits.
For example:

U-Boot SPL 2015.10-00532-g482dc88 (Jan 03 2016 - 10:05:42)
Part number: DART-6U-A01
Assembly: AS11
Date of production: 2015 Dec 31
DART-6UL configuration: eMMC WIFI
Ram size: 512
Boot Device: SD

As explained in the above Build Results table we have 4 optional configurations.
We implemented in U-Boot and automatic device tree selection, so when kernel boots, the U-Boot will load the corresponding device tree according to On-SOM configuration.

Boot From
SOM Internal FLASH
Device Tree selected
SD eMMC Don't Care imx6ul-var-dart-sd_emmc.dtb
SD NAND Don't Care imx6ul-var-dart-sd_nand.dtb
eMMC eMMC Yes imx6ul-var-dart-emmc_wifi.dtb
eMMC eMMC NO imx6ul-var-dart-sd_emmc.dtb
NAND NAND YES imx6ul-var-dart-nand_wifi.dtb
NAND NAND NO imx6ul-var-dart-sd_nand.dtb

Note: Boot from SD card eliminates Wifi as the Wifi and SD card are using same SDIO interface.
A typical use-case, is to boot from SD card, flash eMMC or NAND flash, and re-boot form eMMC/NAND to have Wi-Fi operational.

6.3 Disable Automatic Device Tree selection

To disable the automatic device tree selection in U-Boot:

$ setenv var_auto_fdt_file=N
$ saveenv

Now you can set the device tree to meet your requirments. For example:

$ setenv fdt_file=imx6ul-var-dart-sd_emmc.dtb
$ saveenv

Will select device tree that has SD and eMMC regardless if the SOM has WIFI.

$ setenv fdt_file=imx6ul-var-dart-sd_nand.dtb
$ saveenv

Will select device tree that has SD and NAND regardless if the SOM has WIFI.

Make sure you don't set am illegal value like "imx6ul-var-dart-sd_nand.dtb" in a SOM that has eMMC flash.

7 Flash images to NAND/eMMC

Please refer to DART-6UL NAND Flash Burning

8 QT5/Embedded runtime

8.1 Environment Variables

The QT5/Embedded require environment variables to run correctly. DART6Ul support QT Embedded over Linux Frame Buffer. For example /etc/profile.d/tslib.sh can be edited. The following example enable touch, mouse and keyboard:

export TSLIB_TSDEVICE='/dev/input/touchscreen0'
export TSLIB_CALIBFILE='/etc/pointercal'
export TSLIB_CONFFILE='/etc/ts.conf'
export TSLIB_FBDEVICE='/dev/fb0'
export TSLIB_PLUGINDIR='/usr/lib/ts'

export QT_QPA_PLATFORM=linuxfb:fb=/dev/fb0:size=800x480:mmSize=800x480
export QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS='/dev/input/touchscreen0'
export QT_QPA_GENERIC_PLUGINS='tslib:/dev/input/touchscreen0,evdevmouse:/dev/input/event5,evdevkeyboard:/dev/input/event3'

8.2 Running Application

$ cd /usr/share/qt5/examples/
$ touch/dials/dials --platform linuxfb
$ gui/rasterwindow/rasterwindow --platform linuxfb
$ touch/fingerpaint/fingerpaint  --platform linuxfb
$ widgets/mainwindows/mainwindow/mainwindow --platform linuxfb


The UBIFS image we create by default is for 512MiB NAND flash.
You can change the size by editing ~/var-imx-yocto-krogoth/sources/meta-variscite-imx/conf/machine/imx6ul-var-dart.conf and comment/uncomment the relevant section.

10 Update Yocto Meta-Variscite

From time to time we will post updates to meta-variscite that will include new features and bug fixes.
Follow the instructions below to update your tree:

$ cd ~/var-imx-yocto-krogoth/sources/meta-variscite-imx/
$ git fetch origin
$ git checkout Krogoth-imx-4.1.15-var01
$ git pull

Setup your enviroment:
$ cd ~/var-imx-yocto-krogoth

For X11 image:
$ MACHINE=imx6ul-var-dart DISTRO=fsl-imx-x11 source var-setup-release.sh -b build_x11

For FB image:
$ MACHINE=imx6ul-var-dart DISTRO=fsl-imx-fb source var-setup-release.sh -b build_fb

In order to update the kernel and U-Boot:
$ bitbake -c cleanall u-boot-variscite linux-variscite cryptodev-module

For GUI image:
$ bitbake -c clean fsl-image-gui

For Qt5 image:
$ bitbake -c clean fsl-image-qt5

and build your image:

For GUI image:
$ bitbake fsl-image-gui

For Qt5 image:
$ bitbake fsl-image-qt5

11 Make changes to the rootfs

The following is usually not the recommended way to work with Yocto.
You should usually create new specific recipes (.bb files) and/or append to specific present recipes by using .bbappend files.
However, if you are not yet experienced enough with Yocto, and you just want to quickly add your files to the the resultant filesystem (or make any other change to it), you can do it in a general way, by using the following variable:


    Specifies a list of functions to call once the OpenEmbedded build system has created the root filesystem. You can specify functions separated by semicolons:

         ROOTFS_POSTPROCESS_COMMAND += "function; ... "                  

    If you need to pass the root filesystem path to a command within a function, you can use ${IMAGE_ROOTFS},
    which points to the directory that becomes the root filesystem image. See the IMAGE_ROOTFS variable for more information. 

The functions will be called right after the root filesystem is created and right before it is packed to images (.sdcard, .ubi, .tar.bz2, etc.).

11.1 Example

Let's say you have your files that you want to put in the filesystem arranged on your host under a directory called /my_rootfs_additions, like the following:

├── data
│   ├── example.m4v
│   └── example.bin
├── etc
│   └── example.conf
└── home
    └── root
        └── .example

And let's say you want to build the fsl-image-gui image.

Create a file called ~/var-imx-yocto-krogoth/sources/meta-variscite-imx/recipes-images/images/fsl-image-gui.bbappend
with the following content:

add_my_files() {
    cp -r /my_rootfs_additions/*  ${IMAGE_ROOTFS}/


Now, when you bitbake fsl-image-gui, the files in /my_rootfs_additions will be added to the rootfs (be careful when overwriting files).

12 Useful Bitbake commands

Bitbake Cheat Sheet

Useful bitbake commands

i.MX Yocto Project: ltib versus bitbake