Hello, I have MacPorts on my Mac Pro and all the packages that I've installed are being compiled in 32-bit mode. For example, I installed gcc42 and the result doesn't take -m64. Or, some of my code compiles fine with g++-4.0 -m64 but then I can't link with libraries installed by MacPorts, because they are 32-bit [the (expected) error is 'ld64 warning : in xxx, file is not of required architecture', plus lots of 'Undefined symbols: ...']. These are exclusively Unix-style/command line applications. I've tried compiling some packages on my own and I noticed that config.guess reports i686-apple-darwin8.7.3 or i386-apple-darwin8.7.3 (same as uname, in fact) so that packages just go the 32-bit route. In particular, I hacked the config.guess of libgmp to return x86- unknown-darwin8.7.3 and it compiled fine, but then failed to compile the tests and I gave up. This isn't covered on the FAQ (that I see), so I thought I'd ask here. How can I make MacPorts compile for x64? Even better, is there a way to compile and install both versions of the libraries? Thanks, Daniel.