Find the answer to your Linux question:
Results 1 to 6 of 6
I'm trying to compile a 32bit elf on an intel 64bit system. I'm using -m32 and g++ is very unhelpfully linking to the wrong library path. It should look in ...
Enjoy an ad free experience by logging in. Not a member yet? Register.
  1. 03-20-2013 #1
    zeroth
    zeroth is offline
    Just Joined!
    Join Date
    Aug 2010
    Posts
    31

    g++ -m32 not working.

    I'm trying to compile a 32bit elf on an intel 64bit system. I'm using -m32 and g++ is very unhelpfully linking to the wrong library path. It should look in /usr/lib/gcc/i686-linux-gnu/, not /usr/lib/gcc/x86_64-linux-gnu/

    And what exactly is the difference between /usr/lib/gcc/i686-linux-gnu/ and /usr/lib32 ?

    The direcotry /usr/lib/gcc/x86_64-linux-gnu/ has an empty folder and a symlink, and nothing else whatsoever.

    Code:
    caibbor@helios ~ $ g++ -m32 -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.2-2ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1)
    list of packages I have installed:
    Code:
    caibbor@helios ~ $ dpkg -l '*g++*'
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                       Version                    Architecture               Description
+++-==========================================-==========================-==========================-==========================================================================================
ii  g++                                        4:4.7.2-1ubuntu2           amd64                      GNU C++ compiler
ii  g++-4.6                                    4.6.3-10ubuntu1            amd64                      GNU C++ compiler
un  g++-4.6-multilib                           <none>                                                (no description available)
ii  g++-4.7                                    4.7.2-2ubuntu1             amd64                      GNU C++ compiler
ii  g++-4.7-multilib                           4.7.2-2ubuntu1             amd64                      GNU C++ compiler (multilib files)
ii  g++-multilib                               4:4.7.2-1ubuntu2           amd64                      GNU C++ compiler (multilib files)
ii  libconfig++9:amd64                         1.4.8-5                    amd64                      parsing and manipulation of structured configuration files(C++ binding)
un  libg++2.8-dev                              <none>                                                (no description available)
un  libg++27-dev                               <none>                                                (no description available)
un  libg++272-dev                              <none>                                                (no description available)
caibbor@helios ~ $ dpkg -l '*multilib*'
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                       Version                    Architecture               Description
+++-==========================================-==========================-==========================-==========================================================================================
un  g++-4.6-multilib                           <none>                                                (no description available)
ii  g++-4.7-multilib                           4.7.2-2ubuntu1             amd64                      GNU C++ compiler (multilib files)
ii  g++-multilib                               4:4.7.2-1ubuntu2           amd64                      GNU C++ compiler (multilib files)
un  gcc-4.6-multilib                           <none>                                                (no description available)
ii  gcc-4.7-multilib                           4.7.2-2ubuntu1             amd64                      GNU C compiler (multilib files)
ii  gcc-multilib                               4:4.7.2-1ubuntu2           amd64                      GNU C compiler (multilib files)
caibbor@helios ~ $ dpkg -l '*libc6*'
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                       Version                    Architecture               Description
+++-==========================================-==========================-==========================-==========================================================================================
ii  libc6:amd64                                2.15-0ubuntu20             amd64                      Embedded GNU C Library: Shared libraries
ii  libc6:i386                                 2.15-0ubuntu20             i386                       Embedded GNU C Library: Shared libraries
un  libc6-amd64                                <none>                                                (no description available)
ii  libc6-dbg:amd64                            2.15-0ubuntu20             amd64                      Embedded GNU C Library: detached debugging symbols
ii  libc6-dev:amd64                            2.15-0ubuntu20             amd64                      Embedded GNU C Library: Development Libraries and Header Files
ii  libc6-dev:i386                             2.15-0ubuntu20             i386                       Embedded GNU C Library: Development Libraries and Header Files
ii  libc6-dev-i386                             2.15-0ubuntu20             amd64                      Embedded GNU C Library: 32-bit development libraries for AMD64
ii  libc6-i386                                 2.15-0ubuntu20             amd64                      Embedded GNU C Library: 32-bit shared libraries for AMD64
un  libc6-i686                                 <none>                                                (no description available)
un  libc6.1                                    <none>                                                (no description available)
un  libc6.1-dev                                <none>                                                (no description available)
    Reply With Quote Reply With Quote
  2. 03-21-2013 #2
    bsdtux
    bsdtux is offline
    Just Joined!
    Join Date
    Sep 2012
    Location
    Nashville, TN
    Posts
    67
    /usr/lib32 is where Linux stores it's 32 bit shared libraries. Like libdvdcss.so or libreadline.so. /usr/lib/gcc/i686-linux-gnu/ I would think is where it contains some of the header files for development using gcc or g++. However you say it is empty which is interesting. Mine show a couple of object files but for the most part the main files for c or c++ exists in /usr/include/
    Reply With Quote Reply With Quote
  3. 03-21-2013 #3
    zeroth
    zeroth is offline
    Just Joined!
    Join Date
    Aug 2010
    Posts
    31
    Quote Originally Posted by bsdtux View Post
    /usr/lib/gcc/i686-linux-gnu/ I would think is where it contains some of the header files for development using gcc or g++. However you say it is empty
    no, this is what I said:

    Quote Originally Posted by zeroth View Post
    The direcotry /usr/lib/gcc/x86_64-linux-gnu/ has an empty folder and a symlink, and nothing else whatsoever.
    /usr/lib/gcc/i686-linux-gnu/ has lots of stuff, my problem is that g++, when being explicitly told to use 32-bit executables, is looking in /usr/lib/gcc/x86_64-linux-gnu/ instead of /usr/lib/gcc/i686-linux-gnu/ as I show via g++ -m32 -v in the original post.

    How do I get it to look in the right place? (right place being /usr/lib/gcc/i686-linux-gnu/)
    Reply With Quote Reply With Quote
  4. 03-21-2013 #4
    bsdtux
    bsdtux is offline
    Just Joined!
    Join Date
    Sep 2012
    Location
    Nashville, TN
    Posts
    67
    Ok sorry for mis reading that. Try doing the following
    Code:
    g++ -m32 -c test.cpp -o test.o
g++ -m32 -L/usr/lib/gcc/i686-linux-gnu/ -lstdc++ test.o -o test # If that doesn't work try changing -L to -L/usr/lib32
    Reply With Quote Reply With Quote
  5. 03-21-2013 #5
    zeroth
    zeroth is offline
    Just Joined!
    Join Date
    Aug 2010
    Posts
    31
    Quote Originally Posted by bsdtux View Post
    Ok sorry for mis reading that. Try doing the following
    Code:
    g++ -m32 -c test.cpp -o test.o
g++ -m32 -L/usr/lib/gcc/i686-linux-gnu/ -lstdc++ test.o -o test # If that doesn't work try changing -L to -L/usr/lib32
    I've tried that. It may change the linker's search path, but it doens't change the target, which is still x86_64
    Reply With Quote Reply With Quote
  6. 03-22-2013 #6
    drl
    drl is offline
    Linux Engineer drl's Avatar
    Join Date
    Apr 2006
    Location
    Saint Paul, MN, USA / CentOS, Debian, Solaris, SuSE
    Posts
    1,199
    Hi.

    I installed g++-multilib. Then I ran this script:
    Code:
    #!/usr/bin/env bash

# @(#) s1	Demonstrate g++ compile, link, execute.

# Section 1, setup, pre-solution.
# Infrastructure details, environment, commands for forum posts. 
# Uncomment export command to test script as external user.
# export PATH="/usr/local/bin:/usr/bin:/bin"
set +o nounset
pe() { for i;do printf "%s" "$i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
C=$HOME/bin/context && [ -f $C ] && . $C g++ ldd
set -o nounset
pe

FILE=${1-one.cpp}

# Section 2, display  file.
head $FILE

# Section 3, solution.

pl " Results, 32-bit object files are:"
rm -f *.o a.out
g++ -m32 -c $FILE
file *.o

pl " Output from 32-bit link and execute:"
g++ -m32 *.o -lm
./a.out

pl " Libraries used by this executable, $( file a.out):"
ldd a.out

# Remove debris.
rm -f a.out *.o

exit 0
    producing:
    Code:
    $ ./s1

Environment: LC_ALL = C, LANG = en_US.UTF-8
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.0.0-13-generic, x86_64
Distribution        : Ubuntu 11.10 (oneiric on Debian wheezy/sid) 
bash GNU bash 4.2.10
g++ (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1
ldd (Ubuntu EGLIBC 2.13-20ubuntu5.3) 2.13

#include <iostream>

using namespace std;

int main()
{
  cout << " Hello, world from c++" << endl;
  return ( 0 );
}

-----
 Results, 32-bit object files are:
one.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped

-----
 Output from 32-bit link and execute:
 Hello, world from c++

-----
 Libraries used by this executable, a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, not stripped:
	linux-gate.so.1 =>  (0xf7747000)
	libstdc++.so.6 => /usr/lib32/libstdc++.so.6 (0xf764a000)
	libc.so.6 => /lib32/libc.so.6 (0xf74cb000)
	libm.so.6 => /lib32/libm.so.6 (0xf74a1000)
	/lib/ld-linux.so.2 (0xf7748000)
	libgcc_s.so.1 => /usr/lib32/libgcc_s.so.1 (0xf7483000)
    A guess -- ldconfig wasn't run to set the libraries. That was the last reported step when I installed g++-multilib.

    Best wishes ... cheers, drl
    Welcome - get the most out of the forum by reading forum basics and guidelines: click here.
    90% of questions can be answered by using man pages, Quick Search, Advanced Search, Google search, Wikipedia.
    We look forward to helping you with the challenge of the other 10%.
    ( Mn, 2.6.n, AMD-64 3000+, ASUS A8V Deluxe, 1 GB, SATA + IDE, Matrox G400 AGP )
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules