Rescue mode without DIP switches

In case a complete new firmware image (U-Boot, linux kernel, root filesystem) is to be installed, but the the rescue mode cannot be enabled because the DIP switches are not accessible, a workaround is to invalidate the master boot record (MBR) of the eMMC flash:

  • using Linux
dd if=/dev/zero of=/dev/mmcblk0 bs=1024 count=4
  • using U-Boot
mw.b $loadaddr 0 1000; mmc write 0 $loadaddr 0 8

These commands erase the MBR and the system is not bootable anymore afterwards!
The system detects this and switches to rescue mode after a short while, thus a new firmware image can be installed using the MFG-Tool.

  • Last modified: 2022/08/04 15:02