Building an OCaml cross-compiler for an embedded ARM target

Eric Cooper <ecc@cmu.edu>

July 2010

Introduction

This patch modifies the OCaml 3.12 build system to generate OCaml cross-compilers and related tools and libraries for arm-linux targets.

Status and Limitations

I have built and tested OCaml cross-compilers on an amd64 host running Debian with the following targets:

• an ARM-based router running OpenWrt
• a Seagate DockStar (similar to a Marvell Sheevaplug) running Debian

I have not built cross-versions of the dbm, graphics, or labltk libraries.

I have done only limited testing of the cross-tools and libraries. Any suggestions for a test suite would be welcome.

Prerequisites

You need to be able to cross-compile a "Hello, world!" C program and run it on your target system before going any further.

You will need cross-versions of the gcc and binutils packages (specifically, gcc, as, objcopy, nm, and ranlib), as well as the basic C libraries and headers. The tools must be on your PATH.

You also need the OCaml source tarball:

    http://caml.inria.fr/pub/distrib/ocaml-3.12/ocaml-3.12.0.tar.gz or
    http://caml.inria.fr/pub/distrib/ocaml-3.12/ocaml-3.12.0.tar.bz2

Configuring

1. Un-tar the source tarball.
2. Apply the cross-arm patch.
3. Edit the "configure" script:
   1. Specify the desired value for the "prefix" variable (the directory under which the cross-compilers and cross-libraries will be installed). You must have permission to create files and directories there.
   2. Specify the prefix for your ARM cross tools. For example, if your cross-versions of gcc, as, etc. are "arm-linux-gcc", "arm-linux-as", etc., then specify
      cross=arm-linux-
      (note the trailing '-')

Building

1. Run "./configure"
2. Run "make cross"

Installing

If the build finishes without errors, you can install the resulting tools by running "make installcross".