When ConnectCore 8M Mini boots from the eMMC the U-Boot environment is read from eMMC boot partition 2 (device /dev/mmcblk0boot1 in Linux). See Environment variables.

A closed device with a RPMB authentication key programmed sets boot partition 2 as read only. This means the U-Boot environment cannot be overwritten.

To be able to modify the U-Boot environment, you can boot from USB using a signed bootloader image without Trusty and then make your changes.

  1. Follow the steps at 5. Sign the bootloader images to get a u-boot-ccimx8mmdvk.imx.

  2. Use uuu to boot from USB. See Boot U-Boot in USB debug mode.

  3. Add, remove, or modify U-Boot variables.

    For example, create a new variable:

    => env set test "This is a test variable"
  4. Save the environment.

    => env save
    Saving Environment to MMC... Writing to MMC(0)... OK
    => env save
    Saving Environment to MMC... Writing to redundant MMC(0)... OK