NAND Flash emulation?

[Rogan Dawes]

Hi folks,

I am trying to modify a file on a UBI/UBIFS filesystem on a NAND flash
on a locked down i.MX6UL device. I have desoldered the flash, and read
it with an xgecu flash reader, but am now faced with the problem of
trying to decode the flash (FCB, OOB, etc), mount the mtd partition,
modify it, then convert the image back to something that can be written
to the flash chip again.

I have tried nand_sim so far, without any luck. It appears that the
version of UBI is no longer compatible with current kernels.

One alternative is to purchase an imx6ul_evk, solder the NAND onto the
board, and boot from my own kernel. Another alternative I am considering
(purely due to the cost of the EVK), is emulation.

I was wondering whether it might make more sense to try and run the
kernel under emulation, pointing to a different root partition, mount
the flash partitions, modify them under Linux control, and then write
the resulting image back to the flash.

However, it seems that there is no GPMI implementation/emulation in
qemu, and so this seems doomed to failure. Unless, that is, that I try
to implement such emulation myself. I have no idea how complicated a
task this would be, but it seems like it might be simpler than the other
alternatives that I have considered so far.

Does anyone have any pointers on where I should start reading, on how to
accomplish such a task?

Many thanks

Rogan