  The free energies of the conformal field theories dual to charged adS and
rotating adS black holes show Hawking-Page phase transition. We study the
transition by constructing boundary free energies in terms of order parameters.
This is done by employing Landau's phenomenological theory of first order phase
transition. The Cardy-Verlinde formula is then showed to follow quite
naturally. We further make some general observations on the Cardy-Verlinde
formula and the first order phase transition.
