  The H. Ooguri, A. Strominger and C. Vafa conjecture $Z_{BH}=|Z_{top}|^2$ is
extended for the topological strings on generalized CY manifolds. It is argued
that the classical black hole entropy is given by the generalized Hitchin
functional, which defines by critical points a generalized complex structure on
$X$. This geometry differs from an ordinary geometry if $b_1(X)$ does not
vanish. In a critical point the generalized Hitchin functional equals to
Legendre transform of the free energy of generalized topological string. The
examples of $T^6$ and $T^2 \times K3$ are considered in details.
