seL4 Device Driver Framework

The seL4 Device Driver Framework (sDDF) aims to provide interfaces and protocols for writing and porting device drivers to run as seL4 user level programs.

The sDDF is currently under-going active research and development and is largely experimental software.

We are working on developing the protocols and interfaces for various device classes such as:

• Network
• Block
• Serial
• I²C
• Audio

There is a large amount of experimentation on-going for each device class, although the design for the network device class is mostly mature at this point.

The latest design documentation can be found here.

More information about the sDDF project can be found on the Trustworthy Systems website here.

Building and running examples

You can find examples making use of the sDDF in the examples/ directory. Each example has its own README for how to build and run it.

Dependencies

Toolchain

Any C toolchain should work but most testing and experimentation is currently performed with the aarch64-none-elf GCC toolchain distributed by ARM. You can download it from here.

The specific version used for testing is: aarch64-none-elf-gcc (GNU Toolchain for the A-profile Architecture 10.2-2020.11 (arm-10.16)) 10.2.1 20201103.

Microkit SDK

The sDDF is built using the seL4 Microkit but currently relies on some changes to the Microkit that have not yet been upstreamed.

Below are instructions to acquire the Microkit SDK for use with sDDF depending on your development environment.

On Linux (x86-64):

wget https://trustworthy.systems/Downloads/microkit/microkit-sdk-dev-8e40fe8-linux-x86-64.tar.gz
tar xf microkit-sdk-dev-8e40fe8-linux-x86-64.tar.gz

On macOS (Apple Silicon/AArch64):

wget https://trustworthy.systems/Downloads/microkit/microkit-sdk-dev-8e40fe8-macos-aarch64.tar.gz
tar xf microkit-sdk-dev-8e40fe8-macos-aarch64.tar.gz

On macOS (Intel/x86-64):

wget https://trustworthy.systems/Downloads/microkit/microkit-sdk-dev-8e40fe8-macos-x86-64.tar.gz
tar xf microkit-sdk-dev-8e40fe8-macos-x86-64.tar.gz

Developing sDDF

Adding a new driver

At a minimum, each new driver should have the following:

• An example system in examples/ showing off the capabilities of the driver if the device class does not have an example already.
• The README in the example system should contain the following:
  • A brief description of what hardware functionality the driver supports
  • What the example does and how to compile and run it
• The driver should state exactly what documents where referenced (and what version of the documents) to create the driver. If the driver was taken from U-Boot or Linux that should also be mentioned along with how to find the driver's source code in U-Boot/Linux.