gcc won't link with -m32

Question

Trying to compile even the simplest (int main(){}) program with -m32 on a 64-bit system fails:

$ gcc -m32 test.c
/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc.a when searching for -lgcc
/usr/bin/ld: cannot find -lgcc
/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc_s.so when searching for -lgcc_s
/usr/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status

It seems to be still erroneously searching in the wrong directories when -m32 is specified.

libgcc-4.8-dev:i386 is installed and I've verified that the 32-bit libraries are located in /usr/lib/gcc/i686-linux-gnu/4.8/.

I've tried setting and exporting LD_INCLUDE_PATH and LD_LIBRARY_PATH to no avail.

Solution 1

First, you need to install "gcc-multilib" and "g++-multilib"

sudo apt-get install gcc-multilib g++-multilib

Then your current command will work,

$ cat hello.c
#include <stdio.h>

int main(int argc, char *argv[]) {
    puts("Hello, World!");
}
$ uname -a
Linux vbox-1404 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ gcc -m32 hello.c
$ ./a.out
Hello, World!
$ file a.out
a.out: ELF 32-bit LSB  executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=80bdc95e2941e3ba8d7bb7c1682098f20e77cebc, not stripped

Solution 2

This works for me. I'm on Ubuntu 18.04, x86-64.

First, gcc and gcc-multilib must match the version of each other. If you have installed multi versions of gcc on your machine, then you have to specify one version as the priority. For example I choose gcc 4.8:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 51

The greater the last number specified, the more priority it gets. You can check them out by using this command:

update-alternatives --config gcc

Then you have to install the version of gcc-multilib that match the version of gcc:

sudo apt-get install gcc-4.8-multilib

Done.

Comments

[kenorb]

Related: HowTo Compile a 32-bit Application Using gcc On the 64-bit Linux Version

[Vladimir Panteleev]

Note: For C++ programs, g++-multilib will also be required.

[kenorb]

Consider also: libc6-dev-i386.

[Max Barraclough]

Thanks, this just helped me with a cross-compilation issue. I was able to target 64-bit SPARC, but not 32-bit SPARC. I was missing 'gcc-multilib-sparc64-linux-gnu'.

[GregHNZ]

Thanks for the simple hello.c example - I'm trying to build a huge open source stack with a build script that keeps itself entertained for 10 minutes before crashing with this error message. Nice to be able to test the solution without the whole 10 minute wait.