-- edit
Yes, exactly (you were faster )

@taixzo
What about reflashing back to stock partitioning ?
And use moslo p4 for nemo/sailfish. It seems like you dnkwtd ...

If you set the nitdroid / firefox to different partition than p3/home, then you will need to adapt the specific preinits themselves internally.

@coderus: yes, as kernel (nitdroid one) is probably on harmattan rootfs. [may also be different, but here it will be like that]
--edit
erm, NO. Got also confused with taixzos layout again. ubiboot.conf needs to point to kernel partition, preinit_nitdroid needs to mount nitdroid home partition. Sorry.