How to compile a 32-bit binary on a 64-bit linux machine with gcc/cmake
LinuxGcc64 BitCmake32 BitLinux Problem Overview
Is it possible to compile a project in 32-bit with cmake and gcc on a 64-bit system? It probably is, but how do I do it?
When I tried it the "ignorant" way, without setting any parameters/flags/etc, just setting LD_LIBRARY_PATH to find the linked libraries in ~/tools/lib it seems to ignore it and only look in subdirectories named lib64.
Linux Solutions
Solution 1 - Linux
export CFLAGS=-m32
Solution 2 - Linux
$ gcc test.c -o testc $ file testc testc: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.9, not stripped $ ldd testc linux-vdso.so.1 => (0x00007fff227ff000) libc.so.6 => /lib64/libc.so.6 (0x000000391f000000) /lib64/ld-linux-x86-64.so.2 (0x000000391ec00000) $ gcc -m32 test.c -o testc $ file testc testc: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.9, not stripped $ ldd testc linux-gate.so.1 => (0x009aa000) libc.so.6 => /lib/libc.so.6 (0x00780000) /lib/ld-linux.so.2 (0x0075b000)
In short: use the -m32 flag to compile a 32-bit binary.
Also, make sure that you have the 32-bit versions of all required libraries installed (in my case all I needed on Fedora was glibc-devel.i386)
Solution 3 - Linux
In later versions of CMake, one way to do it on each target is:
set_target_properties(MyTarget PROPERTIES COMPILE_FLAGS "-m32" LINK_FLAGS "-m32")
I don't know of a way to do it globally.
Solution 4 - Linux
For any complex application, I suggest to use an lxc container. lxc containers are 'something in the middle between a chroot on steroids and a full fledged virtual machine'.
For example, here's a way to build 32-bit wine using lxc on an Ubuntu Trusty system:
sudo apt-get install lxc lxc-templates
sudo lxc-create -t ubuntu -n my32bitbox -- --bindhome $LOGNAME -a i386 --release trusty
sudo lxc-start -n my32bitbox
# login as yourself
sudo sh -c "sed s/deb/deb-src/ /etc/apt/sources.list >> /etc/apt/sources.list"
sudo apt-get install devscripts
sudo apt-get build-dep wine1.7
apt-get source wine1.7
cd wine1.7-*
debuild -eDEB_BUILD_OPTIONS="parallel=8" -i -us -uc -b
shutdown -h now # to exit the container
Here is the wiki page about how to build 32-bit wine on a 64-bit host using lxc.
Solution 5 - Linux
For C++, you could do:
export CXXFLAGS=-m32
This works with cmake.
Solution 6 - Linux
One way is to setup a chroot environment. Debian has a number of tools for that, for example debootstrap