Hmm, I do not know. But I guess Maemo's mkfs is not really the latest technology! So it should be hard to not fulfill uboots needs? But I really do not know, so please confirm reinob's question. Meanwhile I checked my older (all) configs and I found for nitdroid an entry of ITEM_FSTYPE=vfat Maybe you can try it with ITEM_FSTYPE=ext3 or ITEM_FSTYPE="ext3" and of course run u-boot-update-bootmenu. But I do not think that solves your prob but worth a shot, right?