> This is something that is done as part of the a.out -> ELF conversion
> process, among other things, and it seems to me that gnu cc knows
> about certain target tags and can use the appropriate libraries from
> their tagged directories. For instance, if you're running on an ELF
> machine, and want to compile and link an a.out executable, you can
> tell gcc about that target, and it will go find and link the a.out
> libraries. I haven't done much of this, so I can't be more certain.
You're talking about crosscompilers. It's pretty easy to build one
with binutils and GCC. Just say the configure script using the --host,
--target and --build options where to install 'em to, install headers
and libraries in the right place and you're ready to go. Ok, in real
live it's more complicated, especially libgcc1.a can drive you crazy.
Sane targets, ie all MIPS targets don't need libgcc1.a so live is lots
easier for you.
> The library directory names I have seen used are i486-linux (ELF),
> i486-linuxaout (a.out), i486-unknown-linuxoldld, m68k-linuxaout,
> sparc-sun-solaris2, sparc-sun-sunos4.1, m68k-linux, and
> alpha-linux. I'm sure there are others.
The names you're refering to are the configuration names used by lots
of GNUish software. They consist of a triple cpu-vendor-os; often it's
legal to use an abbreviation or an alias like sunos for sparc-sun-sunos4.
See also the INSTALL file in the GCC distribution. Enumerating all
supported configuration names, abreviations and aliases supported by
GCC and binutils would be a long posting ...
Ralf