16. Rust#
The number of users of the modern programming language Rust grows steadily. Fans can opt for RTEMS as OS when writing Rust applications on embedded devices. The sections of this chapter provide step by step instructions to get started.
There are two basic approaches to use Rust together with RTEMS:
- Bare metal Rust
The Rust compiler translates the application code for a target without operating system – for example
sparc-unknown-none-elf. The disadvantage of this approach is that no standard Rust library is available (#![no_std]in Rust code). The advantage is that all targets supported by both Rust and RTEMS can immediately be used.- Rust with std lib
The Rust compiler translates the application code for an RTEMS specific target – for example
armv7-unknown-rtems-eabi. The advantage is that all functions from the standard Rust library are available. The disadvantage is that such targets are rare.At the time of writing no such target exists. A first target for ARM is planed to be published soon. The reason for the lack of targets is that one must be implemented for each architecture, published to the Rust compiler sources and maintained by someone.
Common to all approaches is the general way how Rust is used with RTEMS:
The RTEMS tools for the architecture are needed. See Install the Tool Suite.
The RTEMS kernel for the BSP is compiled to libraries. See Build a Board Support Package (BSP).
A Rust project for the application code is created and configured.
The Rust code of the application is compiled into a library for the target.
The Rust application library and the RTEMS kernel libraries are linked together into a single executable file.
The executable file is either run in an emulator or loaded onto the hardware and executed there.
At the time of writing, there is no common Rust interface for the pubic RTEMS functions available. Currently, developers must declare RTEMS functions they want to call. This is especially relevant when the Bare metal Rust approach is used.