Tutorials

We have developed a series of tutorials to introduce seL4 and developing systems on seL4.

How to use the tutorials

Depending on your goals and what you want to do with seL4, we suggest different paths to follow through the tutorial material. Choose the most relevant category below and follow the tutorials in the suggested order.

Note that all of these tutorials require C programming experience and some understanding of operating systems and computer architecture. Suggested resources for these include:

• C programming language
  • C tutorial
• Operating Systems:
  • Modern Operating Systems (book)
  • COMP3231 at UNSW
• Computer Architecture
  • Computer Architecture (wikipedia)
  • Instruction Set Architecture (wikipedia)

Evaluation

Goal:

• You want to understand what seL4 is and what benefits it gives.
• You want to understand how seL4 can be used to develop trustworthy systems.
• You want to get your hands a little dirty and see, compile, and run some code.

Follow these tutorials:

1. seL4 overview
2. Introduction tutorial

System Building

Goal:

• You want to build systems based on seL4.
• You want to know what tools are available to do so and how to use those tools.
• You want experience with how to use seL4 and the tools to build trustworthy systems.

Follow these tutorials:

1. seL4 overview
2. Introduction tutorial
3. CAmkES tutorials
4. Virtualisation tutorials
5. MCS tutorial

Platform Development

Goal:

• You want to contribute to development of the seL4 (user-level) platform.
• You want to develop operating system services and device drivers.
• You want to develop seL4-based frameworks and operating systems.

Follow these tutorials:

1. seL4 overview
2. Introduction tutorial
3. seL4 mechanisms tutorial
4. Rapid prototyping tutorials
5. CAmkES tutorials
6. Virtualisation tutorial
7. MCS tutorial

Kernel Development

Goal:

• You want to contribute to the seL4 kernel itself.
• You want to port seL4 to a new platform.
• You want to add new features to the kernel.

Read this first:

• Contributing to kernel code

Then follow these tutorials:

1. seL4 overview
2. Introduction tutorial
3. seL4 mechanisms tutorial
4. MCS tutorial

The Tutorials

Prerequisites

• set up your machine.

Python Dependencies

Additional python dependencies are required to build tutorials. To install you can run:

pip install --user aenum
pip install --user pyelftools

Get the code

mkdir sel4-tutorials-manifest
cd sel4-tutorials-manifest
repo init -u https://github.com/seL4/sel4-tutorials-manifest
repo sync

Doing the tutorials

The top of the source tree contains the kernel itself, and the tutorials are found in the subfolder: “projects/sel4-tutorials”. The tutorial consists of some pre-written sample applications which have been deliberately half-written. You will be guided through filling in the missing portions, and thereby become acquainted with seL4. For each of the sample applications however, there is a completed solution that shows all the correct answers, as a reference. When completing the tutorials you will be initialising and building your solutions with CMake. The general flow of completing a tutorial exercise involves:

# creating a Tutorial directory
mkdir tutorial
cd tutorial
# initialising the build directory with a tutorial exercise
../init --plat <platform> --tut <tutorial exercise>
# building the tutorial exercise
ninja

After initialising your directory you will be setup with half-written source for you to complete. Additinally, a build directory will be created based on your directory name eg tutorial_build.

Your job is to follow the tutorial instructions to complete the application in the tutorial folder.

• The completed sample applications showing the solutions to the tutorial challenges can be retrieved by initialsing a directory with the --solution argument e.g. ../init --plat <platform> --tut <tutorial exercise> --solution

List of tutorials

Introduction tutorial

Before starting tutorials, make sure that you have read through the Prerequisites and in particular Doing the tutorials.

Then, before any other tutorial, do the hello-world tutorial:

1. Hello, World! an introduction to seL4 projects and tutorials.

which will ensure your setup is working correctly.

seL4 mechanisms tutorials

This set of tutorials are for people keen to learn about the base mechanisms provided by the seL4 kernel. You will learn about the kernel API through small exercises that show basic examples.

1. Capabilities an introduction to capabilities in the seL4 kernel API.
2. Untyped user-level memory management.
3. Mapping virtual memory in seL4.
4. Threads how to start a thread using the seL4 API.
5. IPC overview of interprocess communication (IPC).
6. Notifications using notification objects and signals.
7. Interrupts receiving and handling interrupts.
8. Faults fault (e.g virtual memory fault) handling and fault endpoints.

Rapid prototyping tutorials

This set of tutorials provides walkthroughs and exercises for using the dynamic libraries provided in seL4_libs. These libraries are provided as is, and have been developed for rapidly prototyping systems on seL4. They have not been through intensive quality assurance and do have bugs. Contributions are welcome.

1. Dynamic Libraries 1 system initialisation & threading with seL4_libs.
2. Dynamic Libraries 2 IPC with seL4_libs.
3. Dynamic Libraries 3 process management with seL4_libs.
4. Dynamic Libraries 4 timers and timeouts with seL4_libs.

• The slide presentations to guide you through the tutorials are in the following files:

  • projects/sel4-tutorials/docs/seL4-Overview.pdf: This is an overview of the design and thoughts behind seL4, and we strongly recommend you read it before starting the tutorials.
  • projects/sel4-tutorials/docs/seL4-APILib-details.pdf: This is the actual tutorial.

CAmkES tutorials

These tutorials get you started with our component system CAmkES, which allows you to configure static systems through components. CAmkES generates the glue code for interacting with seL4 and is designed for building high-assurance, static systems.

These tutorials work similarly to the SEL4 tutorials in that they are guided by a slide presentation. There are half-completed sample applications, with a set of slides giving instructions, with TASK challenges once again. There are also completed sample solutions.

1. Camkes an introduction to Camkes concepts.
2. Camkes 1 an introduction to Camkes concepts.
3. Camkes 2 an introduction to Camkes concepts.
4. Camkes 3 introduce Camkes hardware components.

• The slide presentations to guide you through the tutorials are in this file: projects/sel4-tutorials/docs/CAmkESTutorial.pdf.

Virtual machines

These tutorials show how to run Linux guests on Camkes and how to communicate between them. Currently these tutorials are for x86 only.

1. Camkes VM Linux using Linux as a guest in the Camkes VM.
2. Camkes Cross-VM communication walkthrough of adding communication between Linux guests in separate VMs.

MCS extensions

The MCS extensions are upcoming API changes to seL4.

1. MCS an introduction to the seL4 MCS extensions.

What next?

You can try building and running seL4test.

Next steps include working on one of our suggested projects or helping to expand the collection of libraries and components available to build seL4-based systems.