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 file system into the internal storage of the VAR-SOM-MX8M-PLUS. In this release the recovery image is distributed inside the release package (.tar.zst), not as a standalone download.

What is inside the release package¶

After extracting the .tar.zst you get the folder var-release-package/ with multiple options. The most common ones are:

var-release-package/mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.wic.zst is the recovery SD card image (this replaces the old direct download).
var-release-package/mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.wic.bmap is the matching bmap file for faster flashing.
var-release-package/yocto/uuu-installer/ is the Yocto/Linux USB flashing folder (UUU).
var-release-package/android/uuu-installer/ is the Android USB flashing folder (UUU).
var-release-package/yocto/var-image-swupdate-*.rootfs.wic.zst and .bmap are Yocto images for flashing or updates.
var-release-package/yocto/var-image-swu-*.rootfs.swu is the SWUpdate package for in-field updates.
var-release-package/yocto/*.spdx.tar.zst is the SBOM.
var-release-package/yocto/*.cve is the security report.

If you are unsure, use the recovery SD card image from the root folder.

Choose your path¶

Recovery SD card (SD boot + flash): use the .wic.zst in the root folder.
USB flashing (UUU): use the uuu-installer/ folders.
Yocto/Linux UUU guide: Booting from USB using UUU (Universal Update Utility)
Android UUU guide: Flashing Android OS using UUU - USB Boot
SWUpdate (in-field update): use the .swu file under yocto/.
Compliance/security: use *.spdx.tar.zst and *.cve under yocto/.

Download the release package¶

Download the release package (.tar.zst) for this release from Variscite:

mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.tar.zst

wget https://variscite-public.nyc3.cdn.digitaloceanspaces.com/DART-MX8M-PLUS/Software/mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.tar.zst

Extract the package (Linux)¶

tar --use-compress-program=unzstd -xf <release-package>.tar.zst

Extract the package (Windows)¶

Use 7-Zip or WinRAR to extract the .tar.zst file.

Write the image to an SD card¶

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

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?*

Preferred method (bmaptool, faster with .bmap):

sudo bmaptool copy var-release-package/mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.wic.zst /dev/sdX

Alternative method (zstdcat + dd):

zstdcat var-release-package/mx8mp__yocto-scarthgap-6.6.y_2.2.2-v1.0__android-15.0.0_1.2.0-v1.1.wic.zst | sudo dd of=/dev/sdX bs=1M && sync

Replace /dev/sdX with your actual device.

Using a Windows based host¶

Download Win32 Disk Imager from: https://sourceforge.net/projects/win32diskimager/ and install it.
Extract the recovery image from the release package (.tar.zst).
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 .img/.wic file you have extracted previously.
Click Write.
After a few minutes, you receive a notification that your SD has been created successfully.

Using a Mac OS X host¶

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

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 Mode is set to SD card
Power up the board - it will boot into Linux from the SD card

Flash from command line¶

Login as root (no password)
From Linux command line, run the following script:

install_yocto.sh

Install Yocto to the SOM's internal storage (follow the printed instructions).

SD card image file tree¶

/opt/images/
└── Yocto
    ├── imx-boot-sd.bin
    └── rootfs.tar.gz

The install_yocto.sh script file is located at /usr/bin/