Building GAP and its packages in 32 bit mode

It is highly recommended that you always run GAP in 64-bit mode, which should be the default on any modern PC. However, if you want to try GAP in 32-bit mode, here's how you do it:

First make sure you have a multi-arch compiler installed. On Debian/Ubuntu you can get this with the command

sudo apt-get install gcc-multilib g++-multilib

Install GAP the usual way, but when you come to do the ./configure command, use the line

./configure ABI=32 --host=i686-linux-gnumake

Later, when you compile any one of its packages (including Semigroups), replace ./configure with the line

./configure CFLAGS=-m32 CXXFLAGS=-m32 LDFLAGS=-m32 --host=i686-linux-gnu

If you want to build GAP in 32-bit mode using the --with-gmp=system option, you'll first need to get hold of a 32-bit version of GMP. On Debian/Ubuntu you should be able to get this with the command

sudo apt-get install libgmp-dev:i386