Instead of putting on risk my current working ML I have cloned and upgraded it on external USB.
Then I have ML on internal HD and Maverick on external USB and both works properly.
the fact is...booting ML (Maverick) from external (internal) HD does not work and I get kernel panic or reboot as soon as the grey apple logo appears.
It looks to me it is a matter of compatibility across bootloaders. Which one is fully compatible with Maverick AND ML ?
Any recommendation on how to fix this issue ? My target is: cloning Maverick into internal HD and have it working.