This thread is somewhat old, but I think it is worth to resurrect it:
It seems the kernel is loaded from a fixed location and one can change the location of the root file system only. While it appears possible to generate and write a valid binary of a customized u-boot environment this would not allow for a simple dual-boot configuration. However, looking into the
u-boot code published by kobo there is an
upgrade from SD card functionality built-in. It is triggered by keeping the power button pressed at power-on and expects a flag being set in the
hardware configuration area on the SD card.
Today I managed to boot from the SD card following these steps (simplified):
- copy contents from internal SD (/dev/mmcblk0) to external SD
- modify hardware configuration on external SD
- with the external SD plugged in power-on the H2O and keep the power button pressed
I will post more details (if there still is interest), but right now I am curious if I can adopt
Marek's or
Guang's Debian system.
Best regards
Stefan