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

Posted on in Categories C Programming, GNU/Open source, Howto last updated December 13, 2006

I had to compile a 32-bit application using GNU gcc on the 64-bit version of Linux.

Luckily, gcc man page directed me to the ‘-m32’ and ‘-m64’ options. These options generate code for 32-bit or 64-bit environments, respectively.

  1. The 32-bit environment sets int, long and pointer to 32 bits and generates code that runs on any i386 system.
  2. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits and generates code for AMD’s x86-64 architecture.

You can pass -m64 or -m32 options as follows to Gnu gcc

For 32 bit version:
$ gcc -m32 -o output32 hello.c
For 64 bit version :
$ gcc -m64 -o output64 hello.c
Run it as follows:
$ ./output32

Long int size is 4 bytes long!

Now let us see 64 bit output:
$ ./output64

Long int size is 8 bytes long!

Sample code – hello.c

#include <stdio.h>
int main(){
        long z; printf("Long int size is %i bytes long!\n", sizeof(z)); return 0;

A note about glibc-devel on 64 bit systems

You may see an error as follows on 64 bit system when you try to build 32 bit app:

/usr/include/gnu/stubs.h:7:27: error: gnu/stubs-32.h:

This error message shows up on the 64 bit systems where GCC multilib feature is enabled, and it indicates that 32 bit version of libc is not installed. To fix this problem, on a CentOS/RHEL 5.x type the following yum command:
# yum -y install glibc-devel.i386 libstdc++-devel.i386
To fix this problem, on a CentOS/RHEL 6.x type the following yum command:
# yum -y install glibc-devel.i686 glibc-devel ibstdc++-devel.i686
To fix this problem on a Debian or Ubuntu Linux type the following apt-get command:
$ sudo apt-get install g++-multilib libc6-dev-i386
To fix this problem on a Suse (SLES) / OpenSUSE Linux type the following zypper command:
# zypper in glibc-devel-32bit

See also

# Additional correction by Braden B and others; Editing by VG – log #

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

30 comment

  1. How can I build x64 target. using -m64 gives error. how can I download the libraries for 64 bit. remember I am using ubuntu and gcc 4.1.2.

    looks like by default gcc compiles x86.

  2. Any ideas how to convince the average ./configure to compile in 32 bit mode? I’m trying to compile pcsx2 (a PS2 emulator) in 32 bit mode because apparently it works better. I did

    export CFLAGS=-m32
    export CXXFLAGS=-m32

    beforehand, and building stuff works. However the problem is that configure correctly realises I’m using a 64 bit processor and set lots of #defines and other things (such as choosing the x86-64 version of an assembly file). This messes up the build. God I hate autotools.

  3. I get a similar error as Vlad:
    In file included from /usr/include/features.h:352,
    from /usr/include/stdio.h:28,
    from slu_util.h:4,
    from slu_sdefs.h:28,
    from sgssv.c:9:
    /usr/include/gnu/stubs.h:7:27: error: gnu/stubs-32.h: No such file or directory


  4. I found this:
    you might want to install glibc-devel.i386 (even if you’re on x64) to fix this problem
    and this:
    On ubuntu 64-bit version, solution is:
    sudo apt-get install g++-multilib

    hope that will solve it.

  5. I faced this error when using ” gcc -m32 -o de ‘/home/atieh/Desktop/debug.o” of course my program is not only in C languge , it ‘s embbeded with assembly.
    here is the error:
    skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.3.3/libgcc.a when searching for -lgcc
    /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.3.3/libgcc.a when searching for -lgcc
    /usr/bin/ld: cannot find -lgcc
    collect2: ld returned 1 exit status

  6. I’m trying to compile a 32-bit app on 64-bit debian. One of the libraries I need is libelf. The link is failing. Any ideas? I’ve installed ia32-libs, and am using the -m32 compiler switch. Thanks for any help you can give me.

  7. Thanks ! Thanks! Thanks!
    I searched the entire Baidu(in china), did not find the answer!,This is where the original!

    No one can give me the answer,but the teacher is here:
    Make sure you have installed the following packages as well:-
    1. libstdc++.i386
    2. libgcc.i386
    3. glibc.i386
    4. glibc-devel.i386

  8. Dear Sir\
    My MAC is 64-bit and I would like to install the following libraries
    1-gawk 2-gmp 3-mpfr 4- mpc 5- libtool 6- gcc 7- hydra 8- mpich2 9- netcdf 10- paralel-netcdf
    So, what is instructions for installation ,Is it as the same instructions if by MAC 32-Bit
    or not
    ALI B Mahmoos

  9. thank you for the gcc command … it is good … BUT

    no, it is NOT working … EVER !

    the PROPER documentation SHOULD INCLUDE also the proper libraries for compiling with the different platform, otherwise this is TOTALLY USELESS, it will ALWAYS GIVE YOU MISSING LIBS ERRORS !

    now, you may think that i have a too loud voice, but i actually try to help your tutorial, also i managed to fix it on my system (mint/ubuntu/debian i used: apt-get install libc6-dev-i386 and managed to get x86 exec on a x64 system)

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