gcc compiler option -m64

[O. Hartmann]

Hello.
To make ist short: On my box (Athlon64 based machine) I run a FBSD 
6.0Beta2 with no 32Bit support and I hope (but do not exactly know) the 
machine is 64Bit only that way without any 32Bit compatibilty.

I see in some compiler hints this undocumented '-m32' or '-m64' option 
of  gcc(1) (undocumented that way as I can not find it in the man pages) 
.  On SPARC64 systems, the system's default gcc compiler implies '-m64'. 
Is this also true for AMD64 FreeBSD 6.X?

My intention is to avoid compiling in some 32Bit libs by accident when 
compiling some C code for my scientific studies.

thanks,
Oliver