Multilib
Enabling the [multilib] repository allows the user to run and build 32-bit applications on 64-bit installations of Arch Linux. [multilib] creates a directory containing 32-bit instruction set libraries inside /usr/lib32/, which 32-bit binary applications may need when executed.
To use the [multilib] repository, uncomment the following from /etc/pacman.conf:
[multilib] Include = /etc/pacman.d/mirrorlist
You will then need to update the package list by running pacman with the -Syyu switch.
Directory structure
A 64-bit installation of Arch Linux with [multilib] enabled follows a directory structure similar to Debian. The 32-bit compatible libraries are located under /usr/lib32/, and the native 64-bit libraries under /usr/lib/.
Removing Multilib
To revert to a pure 64-bit system, uninstalling [multilib]:
Execute the following command to remove all packages that were installed from [multilib]
# pacman -R `LANG=C pacman -Sl multilib | grep installed | cut -d ' ' -f 2`
If you have conflicts with gcc-libs reinstall the 64-bit versions and try the previous command again:
# pacman -S gcc-libs base-devel
Comment out the [multilib] repository in /etc/pacman.conf:
#[multilib] #Include = /etc/pacman.d/mirrorlist
Update your package list by running pacman with the -Syy switch.