This OPAM repository contains an OCaml cross-compiler for Google Android, as well as a few OCaml libraries and programs compiled for Android.
Use the following command to add this repository to the list of repositories used by OPAM:
opam repo add android https://github.com/vouillon/opam-android-repository.git
The following command will list the available packages:
opam list | grep android
The Android NDK (Native Development Kit) is automatically downloaded.
On a 64bit Debian or Ubuntu installation, you need to install
package gcc-multilib, as we have to build 32 bit OCaml binaries
when targeting 32 bit architectures.
Cross-compilation tools use the arm-linux-androideabi- prefix (for
instance, arm-linux-androideabi-ocamlc) to differentiate them from
standard OCaml tools. For convenience, unprefixed binaries are also
available in directory %{bin}%/arm-linux-androideabi/, where
%{bin}% is the directory where OPAM normally puts binaries
(typically, ~/.opam/4.00.1/bin/ for OCaml 4.00.1).
Ocamlfind can be invoked as either:
ocamlfind -toolchain android,arm-linux-androideabi-ocamlfind,%{bin}%/arm-linux-androideabi/ocamlfind.
The Android NDK is in %{lib}%/android-ndk where %{prefix}% is the
directory under which OPAM normally puts libraries (typically,
~/.opam/4.00.1/lib/ for OCaml 4.00.1). The C compiler is called
with the right options when invoked through the OCaml compilers, so
this location only matters if you need to invoke the compiler
directly. See the build script for package android-c-openssh for an
example of how to do it.
Android libraries and binaries are placed in directory
%{prefix}%/arm-linux-androideabi, where %{prefix}% is the
directory under which OPAM normally puts libraries and libraries
(typically, ~/.opam/4.00.1/ for OCaml 4.00.1). For instance,
the path of the unison binary is:
%{prefix}/arm-linux-androideabi/bin/unison
There are a few pitfalls regarding bytecode programs. First, if you
link them without the -custom directive, you will need to use
ocamlrun explicitly to run them. Second, the ocamlmklib command
produces shared libraries dll*.so which are not usable. Thus, you
need to use the -custom directive to successfully link bytecode
programs that uses libraries with mixed C / OCaml code. Shared
libraries should eventually be disabled, but at the moment, the
ocamlbuild plugin of oasis requires them to be created.
Many thanks to Keigo Imai for his OCaml 3.12 cross-compiler patches.