How can I build a 32bit (i386) .deb on a 64bit box?

Question

I have applications which successfully compile with the -m32 switch (in DMD and/or GCC) to produce:

appname: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked
(uses shared libs), for GNU/Linux 2.6.15, not stripped

The source packages I have created work fine, on both 32 bit and 64 bit Ubuntu to build the appropriate binary .debs.

I would like to produce the i386 .deb on the same 64 bit machine i use to produce the 64 bit .deb.

Is this possible, and where should I look for instructions?

Answer 1

The answer depends on the complexity of your build. When the normal 64 bit userland tools suffice for a build, simply specify the architecture via -a

debuild -ai386

However, there are often cases where this doesn't work, and in these cases you'll need pbuilder. pbuilder builds a clean Debian/Ubuntu system in a chroot-ed environment. man pbuilder is a good introduction. To get started, you'll need:

sudo pbuilder --create --architecture i386
sudo pbuilder --build mypackage.dsc

Answer 2

It starts with calling debuild with the -ai386 option, which will change the architecture that the package is built for.

Of course you have to ensure that the package contains the i386 build of the application.

Answer 3

You don't do anything thing different from building a 64bit .deb. Except that you include a 32bit build of your application.

The control file specifies the architecture, so be sure you select the correct one.