ricarkol / ocaml-freestanding

Freestanding OCaml runtime

ocaml-freestanding -- Freestanding OCaml runtime

This package provides a freestanding OCaml runtime suitable for linking with a unikernel base layer. Currently only Solo5 is supported.

License and contributions

All original contributions to this package are licensed under the standard MIT license.

This package incorporates components derived or copied from musl libc, OpenBSD, OpenLibm and other third parties. For full details of the licenses of these third party components refer to the included LICENSE file.

The OCaml runtime ("OCaml Core System") built by this package is distributed under the terms of the GNU LGPL version 2.1 with a special exception for static or dynamic linking to produce an executable file. For details refer to the LICENSE file included in the version of the ocaml-src OPAM package installed on your system as a dependency when you build this package.

Components

The following components are built and installed:

In PREFIX/lib/ocaml-freestanding:

• libnolibc.a: libc interfaces required by OCaml runtime.
• libopenlibm.a: libm required by OCaml runtime.
• libasmrun.a, libotherlibs.a: OCaml native code runtime.

In PREFIX/include/ocaml-freestanding/include:

• Header files for nolibc and openlibm.

In PREFIX/include/ocaml-freestanding/include/caml:

• Header files for OCaml runtime.

Downstream packages should use pkg-config --cflags ocaml-freestanding when compiling C code using these components and pkg-config --libs ocaml-freestanding during the link step.

Supported compiler versions

Tested against OCaml 4.02.3, 4.03.0 and 4.04.0. Other versions will require changing configure.sh.

Porting to a different (uni)kernel base layer

Assuming your unikernel base layer is packaged for OPAM in a similar fashion to Solo5 this should be as simple as:

1. Adding the appropriate clauses to determine the OPAM packages required and FREESTANDING_CFLAGS for compilation to configure.sh.
2. Implementing a nolibc/sysdeps_yourkernel.c.

Note that the nolibc code is intentionally strict about namespacing of APIs and header files. If your base layer exports symbols or defines types which conflict with nolibc then the recommended course of action is to fix your base layer to not export anything defined by "POSIX" or "standard C".

Updating the vendored copy of OpenLibm

OpenLibm is "vendored" into this repository using git subtree:

git subtree add --prefix openlibm https://github.com/JuliaLang/openlibm.git v0.5.4 --squash

To update the vendored copy of OpenLibm to the newer upstream version TAG, use the following command on a branch and then file a PR:

git subtree pull --prefix openlibm https://github.com/JuliaLang/openlibm.git TAG --squash