Compiling for Y on X
Last Updated: 05, August 2020 at 09:21:13
Platform tools: Dune
Overview
Cross-compiling in OCaml is still an experimental feature, but there are plans to make it a fully supported one in the future.
Cross-compiling allows a programmer on, for example, an x86 machine to compile OCaml code to run on a RISC-V device. Usually the target architecture is the same as the architecture our machine is running on. This is particularly useful for embedded devices running architectures like ARM-32, ESP-32 or RISC-V.
Recommended Workflow
Building for Different Architectures
Dune has built-in support for cross-compilation thanks to toolchains in OCamlfind. To work with cross-compiling you will need the following:
- The appropriate cross-compiling toolchains installed - OCaml uses a C compiler to build the OCaml compiler so a cross-compiling C compiler will be necessary.
- A switch with a cross-compiling repository setup - this will handle installing the OCaml cross-compiler.
Luckily, that is fairly easy. Below, in real world examples, there are some repositories you can use. Instructions for installing say the RISC-V cross-compiler can be found in this Dockerfile. In the future the OCaml compiler will support cross-compilation out-of-the-box but for now you will have to use some modified versions of the compiler.
Testing on Different Operating Systems
Quite often you will be interested in knowing if your library works on different operating systems like Linux, MacOS and Windows. The easiest way to do this is to setup a Github Actions workflow which tests on all three of theses OSes. For more details on how to do this, check out the continuous integration workflow.