VAR-SOM-MX7 Yocto Recovery SD card

From Variscite Wiki
VAR-SOM-MX7 - Yocto recovery SD card

Variscite provides a recovery SD card image that can be used to install the pre-built U-Boot, Linux kernel and the file system into the internal storage of the SOM.

1 Download the recovery SD card image

Download mx7-som-recovery-sd.vXX.img.gz (latest) from Variscite's FTP server:

2 Write the image to an SD card

During the SD card image writing all files and partitions are erased from target device.
Double check that the device is correct to avoid accidentally overwriting a different device and potentially damaging your existing operating system.

2.1 Using a Linux based host

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 umount /dev/sdX?*
$ zcat <image name>.img.gz | sudo dd of=/dev/sdX bs=1M && sync

(Replace /dev/sdX with your actual device)

2.2 Using a Windows based host

  • Download Win32 Disk Imager from: and install it.
  • Extract downloaded <image name>.img.gz file to get <image name>.img (using 7-Zip for example)
  • Insert your SD card into your PC.
    No need to format the SD card before writing the image to it, as the card will be formatted once it will be flashed.
  • Run the file named Win32DiskImager.exe (in Windows 7, 8 and 10 we recommend that you right-click this file and choose “Run as administrator”). 
  • If the SD card (Device) you are using isn’t found automatically. Click on the drop down box and select it 
  • In the Image File box, choose the <image name>.img file you have extracted previously 
  • Click Write 
  • After a few minutes, you receive a notification that your SD has been created successfully. 

2.3 Using a Mac OS X host

Use the dd Utility for MAC OS X to flash .img files to your SD card

3 Recover NAND flash/eMMC

  • Power-off the board.
  • Insert the SD card into the SD card slot of the carrier board (DVK)
  • Make sure the BOOT SELECT DIP switches are set to SD card: Setting the BOOT SELECT DIP switches
  • Power up the board - it will boot into Linux from the SD card

3.1 Flash from GUI

VAR-SOM-MX7 Recovery.png

Touch/Click on the appropriate icon:

  • Install Yocto NAND flash: Flash Yocto to NAND flash
  • Install Yocto eMMC: Flash Yocto to eMMC

3.2 Flash from command line

  • Login as root (no password)
  • From Linux command line, type one of flash options
$	- Flash Yocto into eMMC or NAND Flash (Follow instructions)

3.3 SD card image file tree

└── Yocto
    ├── imx7d-var-som-emmc.dtb
    ├── imx7d-var-som-nand.dtb
    ├── rootfs.tar.bz2
    ├── rootfs.ubi
    ├── u-boot.imx-nand
    ├── u-boot.imx-sd
    └── zImage
The script file is located at /usr/bin/