@cartazio ~/.cabal/config is involved only when running "cabal-install" as a user.  Anyways, the global list of packages registered w/ ghc-pkg is in $GHC_DIR/package.conf.d, and ones installed at the user level is in e.g. $HOME/.ghc/x86_64-linux-7.6.3/package.conf.d, where $GHC_DIR could be something like /usr/lib/ghc-7.6.3.