I also wonder what happens when building x64 miltilibs on an i386 machine. Are x64 multilibs handled as cross-compilation? Maybe such compiler is not used at all in the i386 world.
I have done some research -- it seems that it's handled like this:
- if you're on an x64 host, you configure gcc as multilib with 32/64/x32 targets
- if you're on an x86 host, you configure gcc as multiarch (you can specify the targets with --enable-targets option)
So basically it seems that if you're downwards compatible, use multilib else use multiarch (nice explanation here: https://wiki.debian.org/Multiarch). But it seems not to be a definite rule, for example my Arch Linux contains gcc-multilib only for 64-bit builds. Also it's worth noting that the gcc-multilib packages always contain only additional files (i.e. /lib32 for x64 hosts, /lib64 for i386 hosts), gcc binary is always configured in the way it supports all targets.
Easy solution: make 5475 a separate target => cross compiler (btw this again kind of emphasizes that ColdFire is not really a m68k :)).
Elegant solution: add support for multiarch to m68k.
I don't care that much as I'm cross compiling everything (therefore I can even patch the t-mint file on the fly for each configuration) but it would be nice to have a way how to compile everything nicely on the target platform as well.