Menu
Now in order to compile with 32-bit gcc, just add a flag -m32 in the command line of compiling the 'C' language program. For instance, to compile a file of geek. c through Linux terminal, you must write the following command with -m32 flag. After that you will be able to compile a 32-bit binary on a 64-bit system.
To check this, we have to type this command. gcc –v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu ........... ........... ...........
The -m32 flag tells GCC to compile in 32-bit mode.
gcc-multilib is useful for cross-compiling, that is, compiling a program to run on a different processor architecture. For example, you would need gcc-multilib if you are running on 64-bit Ubuntu and want to compile a program to run on 32-bit Ubuntu (or on ARM etc. you get the idea).
export CFLAGS=-m32
$ 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)
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.
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.
For C++, you could do:
export CXXFLAGS=-m32
This works with cmake.
One way is to setup a chroot environment. Debian has a number of tools for that, for example debootstrap
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With