sdfgen

This repository currently holds libraries to make it easier to develop seL4 Microkit-based systems.

Important

This project is experimental, we are using it internally to get it into a usable state for the public. For development this work exists in a separate repository, but that may change once it has matured (e.g by being apart of the official Microkit repository).

Use

The sdfgen tooling (name temporary) contains libraries for programmatically creating:

• Microkit System Description Files (SDF)
• systems using the seL4 Device Driver Framework (sDDF)
• systems using LionsOS

It has first-class support for use in the following languages:

• C
• Python
• Zig

The Python package is available via pip (on PyPI) and can be installed simply via pip install sdfgen.

Documentation for the Python package can be found here.

Pre-built archives of the C library are available in each release.

Building from source

Dependencies

• Zig (0.14.0-dev.3050+d72f3d353 or higher)
  • See https://ziglang.org/download/, until 0.14.0 is released we rely on a master version of Zig. Once 0.14.0 is released (most likely Feb'25) we can pin to that release.

C library (libcsdfgen)

The C library can be built with:

zig build c

The library will be in zig-out/lib/ and the include headers will be in zig-out/include/. On Linux we default to a static binary for the C library, if you want a dynamic library you can add the -Dc-dynamic=true option.

If you want to output the artefacts to a specific directory, you can so with:

zig build c -p <install dir>

Python

The Python package is supported for versions 3.9 to 3.13. Linux (x86-64) and macOS (Intel/Apple Silicon) are supported.

To build a usable Python package run the following:

python3 -m venv venv
./venv/bin/pip install .

Now you should be able to import and use the bindings:

./venv/bin/python3
>>> import sdfgen
>>> help(sdfgen)

Zig

With Zig you will add this repository to your build.zig.zon either via a URL or path depending on your preference, and then change your build.zig to include the sdf module.

Developing

If you want to modify the tooling, please look at docs/developing.md.

Motivation

Problem

In order to remain simple, the seL4 Microkit (intentionally) does not provide one-size-fits-all abstractions for creating systems where the information about the design of the system flows into the actual code of the system.

A concrete example of this might be say some code that needs to know how many clients it needs to serve. This obviously depends on the system designer, and could easily be something that changes for different configurations of the same system. The Microkit SDF offers no way to pass down this kind of information. For the example described, an easy 'solution' would be to pass some kind of compile-time parameter (e.g a #define in C) for the number of clients. However imagine now you have the same system with two configurations, with two clients and one with three, this requires two separate SDF files even though they are very similar systems and the code remains identical expect for the compile-time parameter. This problem ultimately hampers experimentation.

Another 'problem' with SDF is that is verbose and descriptive. I say 'problem' as the verbosity of it makes it an ideal source of truth for the design of the system and hides minimal information as to the capability distribution and access policy of a system. But the negative of this is that it does not scale well, even small changes to a large SDF file are difficult to make and ensure are correct.

Solution(s)

• Allow for users to easily auto-generate SDF programmatically using a tool called sdfgen.
• Create a graphical user-interface to visually display and produce/maintain the design of a Microkit system. This graphical user-interface will sort of act as a 'frontend' for the sdfgen tool.

The sdfgen tooling is available and being used by sDDF and LionsOS, although still experimental. The GUI for the tooling is still very much a work-in-progress and not ready for use.