building an i386 binary on a ppc machine using gcc

hello all,
using gcc 4.0.1 on a Mac OS X 10.4 (i386) i am able to produce successfully a "ppc" binary
# gcc -arch ppc -o prg prg.c

But I am not able to produce an i386 binary on a "ppc" machine
# gcc -arch i386 -o prg prg.c

/usr/libexec/gcc/i686-apple-darwin8/4.0.1/ld: warning fat file: /usr/lib/gcc/i68 6-apple-darwin8/4.0.1/../../../libSystem.dylib does not contain an architecture that matches the specified -arch flag: i386 (file ignored)
/usr/libexec/gcc/i686-apple-darwin8/4.0.1/ld: Undefined symbols:
___keymgr_dwarf2_register_sections
__cthread_init_routine
_atexit
_errno
_exit
_mach_init_routine
_puts
collect2: ld returned 1 exit status

Why does this happen ?

You'll need to build your own gcc that is "cross target" meaning that the compiler is built to run on PPC, and to compile for i386. You will also need to build binutils for cross building and build the C library with the cross-compiler - and of course any other libraries that you need.

--
Mats

you need to have a toolchain for architecture, one can be built using buildroot: http://buildroot.uclibc.org/ or scratchbox: http://scratchbox.org/