A cargo subcommand for automating feL4 (seL4 for Rust) development

cargo-fel4 seeks to accelerate the pace of Rust development for seL4 environments by automating away the annoyances of building the underlying seL4 codebase, generating useable Rust bindings, and providing a way to get your code into a runnable seL4 application.

Once installed, use cargo fel4 new my-project to create a new feL4 project, which is a regular Rust no_std library project with a few additional configuration frills.

In that project, running cargo fel4 build will generate a seL4 application wrapping your library code from src/lib.rs, and cargo fel4 simulate will run it.

Access to seL4 capabilities is presently through the libsel4-sys library, a thin binding layer around seL4. This wrapper is built and configured according to your feL4 project settings, stored in your project's fel4.toml manifest file.

feL4 projects come with a example property-based test suite to demonstrate how to conduct tests in the feL4 context. Try it out with cargo fel4 test build && cargo fel4 test simulate

cargo-fel4 is released with additional special thanks and attribution to Robigalia, particularly for their startup assembly code and example conventions W.R.T. language items, and of course, to Data61, et al for seL4.

cargo-fel4 works on top of several other tools to operate, so you'll need Rust with Cargo, Xargo, and QEMU to build and run feL4 projects. Additionally, feL4 depends on the libsel4-sys crate, which has its own set of dependencies. Some of the "Building" steps below are actually specific to satisfying libsel4-sys dependencies. cargo-fel4 was developed using Ubuntu Xenial, but other Linux variants should work.

• rust (nightly)
• xargo (for cross-compiling)
• gcc/g++ cross compilers (for ARM targets)
• qemu (for simulation)
• dfu-util (for device deployment)

These instructions cover installing both libsel4-sys and cargo-fel4 dependencies as well as building cargo-fel4.

• Install system package dependencies:

  sudo apt-get install python-pip ninja-build libxml2-utils dfu-util curl
  sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu
  sudo apt-get install gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf
  sudo apt-get install qemu-system-x86 qemu-system-arm

• Install pip package dependencies:

  sudo pip install cmake sel4-deps

• Install Rust nightly and additional components:

  curl https://sh.rustup.rs -sSf | sh
  rustup install nightly
  rustup component add rust-src
  cargo install xargo

• Building cargo-fel4:

  cargo build

After building, cargo-fel4 can be installed with cargo install.

• Install under the nightly toolchain:

  cargo +nightly install cargo-fel4

See the output of cargo fel4 --help for more details.

cargo fel4 --help

A cargo subcommand for automating feL4 (seL4 for Rust) development

USAGE:
    cargo fel4 <SUBCOMMAND>

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

SUBCOMMANDS:
    build       Build a feL4 project
    clean       Remove generated artifacts
    deploy      Deploy a feL4 project
    help        Prints this message or the help of the given subcommand(s)
    new         Create a new feL4 project
    simulate    Simulate a feL4 project with QEMU
    test        Build and run feL4 tests

• Create a New feL4 Project

  To create a new project using cargo-fel4:

  cargo fel4 new my-project
      Created library `my-project` project
  
  $ tree my-project/
  my-project/
  ├── Cargo.toml
  ├── fel4.toml
  ├── src
  │   ├── fel4_test.rs
  │   └── lib.rs
  ├── target_specs
  │   ├── armv7-sel4-fel4.json
  │   ├── README.md
  │   └── x86_64-sel4-fel4.json
  └── Xargo.toml

• Build a feL4 Project

  To build a feL4 project using cargo-fel4:

  cd my-project/
  
  cargo fel4 build

• Simulate a feL4 Project

  To simulate a feL4 project with QEMU via cargo-fel4:

  cd my-project/
  
  cargo fel4 simulate

• Deploy a feL4 Project

  To deploy a feL4 project on to the target platform using cargo-fel4:

  cd my-project/
  
  cargo fel4 deploy

• Running Tests

  cargo-fel4 will generate a basic set of property tests when creating a new project.

  cargo fel4 test

  Just build a feL4 test application:

  cargo fel4 test build

  Simulate a previously-built feL4 test application:

  cargo fel4 test simulate

  Deploy a feL4 test application:

  cargo fel4 test deploy

• DFU Deployment on the TX1 Platform

  To deploy a feL4 application via DFU, be sure to have a serial connection set up in order to interact with the U-Boot boot loader.

  Attach the USB-mini end of a USB cable to the USB-mini port on the TX1. Then plug in the power supply for the TX1 and power it on.

  Once the TX1 is powered on, watch the serial output so you can stop the boot process at the U-boot command prompt.

  Then at the U-boot command prompt, enter the following:

  setenv dfu_alt_info "kernel ram 0x83000000 0x1000000"
  setenv bootcmd_dfu "dfu 0 ram 0; go 0x83000000"
  saveenv

  To make U-boot enter its DFU server mode, type:

  run bootcmd_dfu

  U-boot will wait until an image has been uploaded.

  You can now deploy a cargo-fel4 application image from the host machine:

  cargo fel4 deploy

• Configuration

  cargo-fel4 is configured through a fel4.toml manifest file.

  The manifest file is responsible for prescribing a high-level configuration for cargo-fel4 infrastructure, as well as the underlying libsel4-sys package CMake build system.

  Boolean properties specified in the fel4.toml are applied as Rust features to feL4 projects during cargo fel4 build, so it's possible to do compile-time configuration to account for variations in available seL4 options.

  The fel4.toml manifest resides in the project's root directory, and contains several properties related to the location of input/output artifacts. These path properties are relative to project's root directory.

  For example, a newly generated feL4 project contains the following in fel4.toml:

  [fel4]
  artifact-path = "artifacts"
  target-specs-path = "target_specs"
  ...
  

  Output artifacts produced during a cargo-fel4 build will be placed in the directory specified by the artifact-path property.

  Target specification files available to cargo-fel4 are located in the directory specified by the target-specs-path property.

  cargo fel4 new my-project
  
  # The fel4.toml is generated at the project's root directory
  my-new-project/fel4.toml
  
  # Output artifacts produced by the build
  my-new-project/artifacts/
  
  # Rust target specifications available to cargo-fel4
  my-new-project/target_specs/

  It is advisable to clean the build cache when changing either the Rust target triple or the platform configuration. This can be done with cargo-fel4:

  cargo fel4 clean

  See the fel4-config and libsel4-sys packages for more configuration information.

  See the target specifications README for more information about the specifications shipped with cargo-fel4.

cargo-fel4 manages its own tests with the standard Rust test framework, plus proptest for property-based testing.

Building the tests is as simple as:

cargo build --tests

Running the tests for cargo-fel4 (as opposed to the tests within a given feL4 project) requires installing the standard dependencies listed earlier. cargo-fel4's internal tests can be exercised by running:

cargo test

Please see the LICENSE file for more details