libtool picks up 64-bit library when I tries to build 32-bit program

Question

I have a GNU build system with autoconf-2.69, automake-1.14.1, libtool-2.4.2. I've configured with --host=i686-linux on a x86_64 RHEL6 host OS to build a 32-bit program. The libtool command seems to be:

/bin/sh ../libtool  --tag=CXX   --mode=link g++ -I/home/STools/RLX/boost/include/boost-1_44  -m32 -g3 -Wall -static  -o engine engine-main.o ../components/librlxvm.la /home/STools/RLX/boost/include/boost-1_44/../../lib/libboost_program_options-gcc42-mt-1_44.a  -lz -lpthread -ldl  -lrt -ldl -lz -lm

But the real command is to search the 64-bit libraries not the 32-bit libraries as shown below:

libtool: link: g++ -I/home/STools/RLX/boost/include/boost-1_44 -m32 -g3 -Wall -o engine engine-main.o  -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/x86_64-unknown-linux-gnu/libstdc++-v3/src -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs -L/home/robert_bu/src/gcc/gcc-4.2.2/build-x86_64/./gcc ../components/.libs/librlxvm.a /home/STools/RLX/boost/include/boost-1_44/../../lib/libboost_program_options-gcc42-mt-1_44.a /home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64/libstdc++.so -L/lib/../lib64 -L/usr/lib/../lib64 -lc -lgcc_s -lrt -ldl -lz -lm -pthread -Wl,-rpath -Wl,/home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64 -Wl,-rpath -Wl,/home/STools/RLX/gcc-4.2.2-x86_64/lib/../lib64

The --host config seems to have no effect. Is there anyway to tell libtool that 32-bit libraries are what we want?

Answer 1

It seems that libtool uses "CC", "CXX" to check the library search path. After I set CC to "gcc -m32", and CXX to "g++ -m32", it works. So libtool does not add "-m32" automatically even if I try to build a 32-bit program on a 64-bit system.

Answer 2

You're being hit by the problem of libtool .la files expansion. In particular libstdc++.la is being expanded for you to a full path rather than a simple -lstdc++.

My suggestion is to remove .la file from the SDK you're using (/home/STools). This way libtool can't assume things for you. Usually the ones you have in the system are fine, because the libraries are already in the search path, so it does not need to use -rpath or the full path to the .so file.

Depending on how well the SDK was crafted, this might or might not work correctly, so take it with a grain of salt.