I asked the question on the commits list a few weeks ago from the gcc2h side and Ingo replied with this, I suspect it's similar for building the other way? > How do we switch over to build gcc4 versions? > If you mean building for gcc 4 on a gcc 2 hybrid Haiku, add SECONDARY_TARGET_**ARCHITECTURES="x86" to your haikuports.conf and then just do "haikuporter <port>_x86". For building x86 gcc 4 primary architecture packages you need a respective Haiku.