UBI+UBIFS on Read-Only NAND

[Richard Genoud]

2013/12/5 Thomas Herrmann <THerrmann at adwin.de>:
> We had an old JFFS based system that had a dip switch connected to the
> write-enable pin of the flash device, and it worked as expected. Users
> were able to configure and use the system in r/w mode and then "lock"
> the configuration.
>
> I tried the same with our newer hardware, and UBI/UBIFS. I did not use
> static volumes, since write support is essential for initial setup.
> However, the system will not boot if the flash is write-protected in
> hardware, because UBI assumes that it is R/W.
>
> What is the suggested solution for such a setup? I could not find
> anything in the FAQ or in the archive, but I may have been searching for
> the wrong keywords...

AFAIK, UBI is not design to be used on a write protected NAND.
As it is basically a wear-leveling / bad block handling layer, it
wouldn't make much sense without a write capability.
The closest use case I can imagine would be to mount the UBIFS volume
RO by default and remount it RW when a gpio button is pushed.
But with a dip switch directly on the NAND WP pin, I don't think
there's an UBI based solution.

Richard.