hi all,
i have a 64 bit linux machine.

$uname -a
Linux SVRDELLD30 2.6.9-42.ELsmp #1 SMP Tue Aug 15 10:35:26 BST 2006 x86_64 x86_64 x86_64 GNU/Linux

here by default gcc creates 64 bit executable. but for some reason i want to create 32bit executable.

first i want to create 32 bit object files(.o files) and then i want to link those object files.

Please suggest me suitable gcc options.

Thanks and Regards,
uttam hoode

If you have a toolchain that supports multilib, then you would pass the -m32 flag to the compiler to generate 32-bit, i386 compatible code. If you don't have a toolchain with multilib support, you can't create 32-bit apps or libs on an x86_64 system.

$gcc -print-multi-lib
.;
32;@m32


$gcc -print-multi-os-directory -m32; gcc -print-multi-os-directory -m64; gcc -print-multi-os-directory
../lib
../lib64
../lib64

when i gave -m32 option gcc created 32 bit object files....

$file Logger.o
Logger.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped

but im getting error while linking .o files.

Thanks and Regards,
uttam hoode

Try passing "-m32" to the linker command.

The actual error might be more helpful.

If you are using GNU ld, and it complains about incompatible objects, try something like this instead:

hi weibullguy,
im getting following errors while linking(using gcc)


/usr/bin/ld: warning: i386 architecture of input file `global.o' is incompatible with i386 output
/usr/bin/ld: warning: i386 architecture of input file `Logger.o' is incompatible with i386 output
/usr/bin/ld: warning: i386 architecture of input file `tap311.o' is incompatible with i386 output

when i used ld with -m elf_i386 (as suggest by osor) i got follwing errors but executable is created

ld: warning: cannot find entry symbol _start; defaulting to 0000000008048a80


and executable is throwing this error


-bash: ./myapp: /usr/lib/libc.so.1: bad ELF interpreter: No such file or directory


Thanks and Regards,
uttam hoode

Try adding "-lcrt0" to make sure you are getting the C startup code.

An alternative to all these shenanigans is to use gcc as your linker frontend. It will automatically pick the correct options for you:

hi all,
created object files and i am able to link them using -m32....now i have a 32bit executable on x86_64 machine...but when i tried to execute i am getting segmentation fault error.

(i copied 32bit executable from i386 machine to x86_64 machine and it s working fine. both i386 and x86_64 machines have same version of gcc and glibc)

Thanks and Regards,
uttam hoode

Hi

I have the same problem :
I have a Xeon 64bit processor, Fedora 8 x86_64 :
And another machine with a 32bit processor, with Fedora core 5 :
I have a simple C code: main.c:
When I compile this on my 32bit machine, the executable run on both machine.

When I compile this on my 64bit machine with the option -m32:
It run only on the 64bit machine. On the other on, I got this error :
With google, it seems that am the only human with this problem (X_X)

Here my gcc version :
64bit :
32bit :

Have you considered that the architecture is being used during compilation and/or linking? I.e., there may be architecture-specific optimizations available to your Xeon over your 32-bit machine apart from its 64-bittedness.

On your 64-bit machine, try something like this:

1 members found this post helpful.

Sorry for the late reply.

I tried the option -march=i686 : nothing changed ... (I tried also i386 i586)

... I don't know ...

Hello

My problem is just opposite. I want to build x64 application from my 32 bit ubuntu machine with gcc 4.1.2 installed.

I have test.cpp

#include <iostream>

int main()
{
cout<<"hello world"
return 0;
}

now compiling this code using
g++ -m64 test.cppI get error.

/usr/bin/ld: skipping incompatible /usr/lib/gcc/i486-linuxgnu/4.1.2/../../../libm.so when searched for lm

/usr/bin/ld: cannot find lm.

waiting for your suggestion.

Regards
Amit

YOU CANT RUN A 32 BIT EXE ON A 64BIT MACHINE!!! WHAT KIND OF PERSON KNOWS THE TERMS "32-BIT", "64-BIT", PROGRAMS, BUT DOESNT KNOW THAT??!!