Forum OpenACS Development: Re: Error installing tcl 8.4x (how to solve)
To address the "maybe": check out /web/nsd45/lib/tclConfig.sh which contains most likely the 64bit flags.
I compiled Tcl with --enable-64bit as shown above. In AOLserver I don't see any 64bit flags (tcl cc is gcc -pipe) and config.log doesn't seem to do any checking, but the arch is x86_64. Whatever the reason, I didn't need to put the --enable-64bit option when doing configure for tDOM or AOLserver.