[Haskell-cafe] Cabal: Can only one processor core be used?

Hi I've searched the web and the cabal user guide on how to use more processor cores for compilation via cabal. I couldn't find anything. It looks like only one processor core can be used with cabal, even though (I've read on the web) GHC supports parallel compilation. Cabal compilation times can be a pain. It can't be that you can use only one processor core with cabal, can it ..? Cheers, Volker