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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 filesystem into the internal storage of the VAR-SOM-AM62. 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/am62_yocto-scarthgap-6.12.57_11.02.08.02-v1.0.wic.zst is the recovery SD card image (this replaces the old direct download).

  • var-release-package/yocto/var-image-swupdate-*.rootfs.wic.zst is the Yocto image 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.

  • 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:

wget https://variscite-public.nyc3.cdn.digitaloceanspaces.com/VAR-SOM-AM62/Software/am62_yocto-scarthgap-6.12.57_11.02.08.02-v1.0.tar.zst

Extract the package (Linux)

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

Extract the package (Windows/macOS)

Use 7-Zip 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?*

zstdcat var-release-package/am62_yocto-scarthgap-6.12.57_11.02.08.02-v1.0.wic.zst | \
  sudo dd of=/dev/sdX bs=1M && sync

Replace /dev/sdX with your actual device.

Using a Windows-based host

  • Download Rufus from https://rufus.ie/ and install it.
  • Extract the recovery image from the release package (.tar.zst) using the latest 7-Zip.
  • 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 Rufus.
  • If the SD card (Device) you are using isn’t found automatically, click on the drop-down box and select it.
  • In the Boot selection field, choose the .img/.wic file you extracted previously.
  • Click Start.
  • After a few minutes, you receive a notification that your SD has been created successfully.

Using a Mac OS X host

Use the latest 7-Zip to extract the image, then use bmaptool when a .bmap file is available, or dd, 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

  • Log in 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).

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

SD card image file tree

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