Getting GMP to work with GCC 4.5.2

Question

I'm trying to make a cross compiler with the files from http://crossgcc.rts-software.org/doku.php?id=i386linuxgccformac

I'm on an Intel Mac (10.6.6, x86_64) I compiled: gmp, mpfr, mpc for the cross compiler as 32bit (as I'm on a 64bit Mac) but I'm getting

ld: warning: option -s is obsolete and being ignored
ld: warning: ignoring file /gmp1/lib/libmpc.dylib, file was built for unsupported file format which is not the architecture being linked (i386)
ld: warning: ignoring file /gmp1/lib/libmpfr.dylib, file was built for unsupported file format which is not the architecture being linked (i386)
ld: warning: ignoring file /gmp1/lib/libgmp.dylib, file was built for unsupported file format which is not the architecture being linked (i386)

When compiling GCC with:

--prefix=/usr/local/i386-linux-4.5.2 --target=i386-linux --enable-languages=c --without-headers --disable-shared --disable-threads --disable-nls --with-gmp=/gmp1 --with-gmp-lib=/gmp1 --with-gmp-include=/gmp1 --with-mpfr=/gmp1 --with-mpfr-include=/gmp1 --with-mpfr-lib=/gmp1 --with-mpc=/gmp1 --with-mpc-lib=/gmp1 --with-mpc-include=/gmp1

Also, if I compile GMP with:

./configure --prefix=/gmp1 --host=i386-linux

I get:

configure: WARNING: +----------------------------------------------------------
configure: WARNING: | Cannot determine global symbol prefix.
configure: WARNING: | link -dump -symbols output doesn't contain a global data symbol.
configure: WARNING: | Will proceed with no underscore.
configure: WARNING: | If this is wrong then you'll get link errors referring
configure: WARNING: | to ___gmpn_add_n (note three underscores).
configure: WARNING: | In this case do a fresh build with an override,
configure: WARNING: |     ./configure gmp_cv_asm_underscore=yes
configure: WARNING: +----------------------------------------------------------
checking how to switch to read-only data section... .data
checking for assembler .type directive... 
checking for assembler .size directive... 
checking for assembler local label prefix... configure: WARNING: "link -dump -symbols" failure
configure: WARNING: cannot determine local label, using default L
L
checking for assembler byte directive... .byte
checking how to define a 32-bit word... link: illegal option -- d

Answer 1

Did you use the "ABI=32" option when compiling GMP? If not, I think it will use 64-bit code even if the host/target are specified as i386.

Answer 2

I think that you are confused about which package should be compiled for which platform:

• GCC needs to be compiled for an x86_64 MacOS X host and an i386-linux target.

• GMP, MPC and MPFR are runtime dependencies for GCC. Therefore they also need to be compiled for the GCC host - x86_64 in your case. Therefore, the --host=i386-linux option in the GMP configure command is incorrect.

In general, only libraries that will be linked in the programs compiled by GCC need to be built for the cross-compiler target (e.g. i386-linux). GMP and MPFR are not such libraries, unless your programs are actually using them - in that case you will need to have two copies of such libraries, one for GCC and a cross-build for the target.

EDIT:

Have you considered using MacPorts? It has all the dependencies for your cross-compiler:

• gmp-5.0.1

• mpfr-3.0.0

• libmpc-0.8.2

There is also an older newlib-based cross-compiler for i386:

• i386-elf-gcc-4.3.2

Even if you do not want to use these, you can still have a look at the build instructions in their Portfiles.

The bottom line is:

• Apply whatever patches these libraries need - MacPorts already do that.

• Compile the libraries for your build host i.e. MacOSX/x86_64. That means that in any --host options for their configure calls you should be something along the lines of --host=x86_64-darwin (or whatever your host needs). If configure can figure out the host on its own, you can skip the --host options altogether.

• Compile GCC with --host being your build host (the 64-bit Mac OS X) and a target of i386-linux, e.g. --target=i386-linux. If I were you, I'd start simple with a compiler for the C and C++ languages only.

See also this tutorial. It has some information on how to produce a working toolchain with a proper glibc.

That said, I think that you'd be better off installing a proper Linux distribution in a virtual machine, for a whole bunch of reasons. Is there a reason for you to need a cross-compiler specifically? What do you want to do with that compiler?