Cannot figure out 32 bit on 64 bit crosscompilation

kjell159 · 07-29-2014, 01:43 PM

Can someone explain me what packages I need and how I crosscompile?
I just can't seem to find the solution.

I would like to compile a 32 bit version of a program on my x86_64 bit Fedora Linux.
When I put -m32 on the end of the configuration command for configuring code so I can build it, it does nothing.
I have an Intel core i5 processor.

notKlaatu · 07-29-2014, 02:48 PM

First of all, you need all the 32 bit libs that the application you are compiling needs to build and link to. I deal in c++ more, so I will give an example for that, but it should be the same for C.

Code:

$ g++ -m32 foo.cpp -o foo.bin -L /usr/lib -march=i586
$ file foo.bin
foo.bin: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, not stripped

As long as I have the headers and libs in /usr/lib, that command will work. If I do not, then it will fail; so make sure you have explicitly installed the 32bit versions of what you need to compile against.

You might also need to output 32bit-versions of the object code that your compilation creates; it kind of depends on how complex the build is.

** Look in the GCC man page to see the different CPU types you can set -march to. It's a long man page so do I search for 'corei7' or 'pentium' and that should take you to the right section.