Just in case, here is the strace for reading writing root device on previous devices
http://slexy.org/view/s20aCfat7r

So all this is cool but the best would be to have CAL area documented so we know format of ConF blocks in config partition and also which ones are used and which ones can be safely erased/rewritten (there are multiple old copies lying around when changing same variable ).

When stracing cal-tool -r on N900 it can be seen that libcal is scanning config partition and reading ConF entries.