example_application

example

An example seL4 application which uses selfe-sys to make syscalls and selfe-start to bridge the gap between a bare-bones Rust #[no_std] application and one that will work on the seL4 microkernel.

Highlights

A sel4.toml file sits at the project root, next to the Cargo.toml, and provides the build configuration for the underlying seL4 kernel.

In order for the Rust project to link properly with the seL4 code, the following rustflags are set in .cargo/config:

[build]
rustflags = ["-C", "link-arg=-no-pie", "-C", "link-arg=-nostdlib"]

[target.armv7-unknown-linux-gnueabihf]
linker = "arm-linux-gnueabihf-gcc"

Note also the presence of a selected linker to support the cross-compilation-for-arm use case.

Dependencies

Note that selfe-sys and selfe-start are included as regular Cargo.toml dependencies.

Language Items

In order to let application-builders pick the level of secrecy they want around their failure cases, main.rs defines a #[panic_handler] implementation (albeit one that immediately delegates to an optional helper from selfe-start)

Boot Info

selfe-start exposes to the root task a static selfe_start::BOOTINFO item that represents the kernel-supplied seL4_BootInfo instance from which most information necessary to work with seL4 can derived.

    let bootinfo: &'static seL4_BootInfo = unsafe { &*selfe_start::BOOTINFO };
    // Do work with the boot info instance here

Building

You can build directly with cargo-xbuild or xargo, specifying your Rust target triple as an explicit argument.

Optionally use the environment variable SEL4_CONFIG_PATH to point to your sel4.toml configuration file and the SEL4_PLATFORM env-var to select your desired platform target.

SEL4_PLATFORM=pc99 cargo xbuild --target x86_64-unknown-linux-gnu
SEL4_PLATFORM=sabre cargo xbuild --target armv7-unknown-linux-gnueabihf

Alternately, you can build or run with the selfe tool, executed from this example project's directory.

selfe build --sel4_arch x86_64 --platform pc99 --debug
selfe build --sel4_arch x86_64 --platform pc99 --release

selfe build --sel4_arch aarch32 --platform sabre

selfe simulate --sel4_arch aarch32 --platform sabre