Developing and Maintaining Utils

The Leda teams provides some custom utilities that allow for a more integrated end-user experience. They can be found in the main leda-utils repository on GitHub: eclipse-leda/leda-utils.

The following pages are meant to serve as both internal documentation and general guidelines when developing for Leda.

Bash

Leda uses the classic Bourne shell as its main shell, thus all scripts should be sh-compatible (use the #!/bin/sh shebang). As a Poky+OE-based distro we use BusyBox for core-utils. To check explicitly for “bashisms” in your scripts, the checkbashisms tool might be useful.

Utility-Specific Pages

The bash-based leda-utils are all deployed with the same recipe under the sdv-base packagegroup: meta-leda/meta-leda-components/recipes-sdv/sdv-base.

Rust

The current main branch for leda-distro (and meta-leda) is based on the Kirkstone Yocto/Poky release.

Toolchain version

The version of the Rust toolchain available in OE (Kirkstone) is 1.59.0. Make sure to target 1.59.0 (or earlier) when developing Rust-based utils for leda. To set 1.59.0 as your default Rust version on your development machine:

$ rustup install 1.59.0
$ rustup default 1.59.0

$ cargo --version
cargo 1.59.0 (49d8809dc 2022-02-10)

Generating bitbake recipes with cargo-bitbake

After making sure your toolchain is on version 1.59.0 go trough a clean build of your Rust binary:

$ cd <rust_project_dir>
$ cargo clean
$ rm Cargo.lock
$ cargo build --release

This will make sure the Cargo.lock is re-generated with packages matching the Rust version. The cargo.bbclass on which Rust recipes are based, requires all Rust crates + their version (matching the Cargo.toml) to be specified as a “SRC_URI +=”. This can become tedious and error-prone if done by hand. That’s why meta-rust provides a tool called cargo-bitbake that generates a minimal recipe with all the crates it finds in the Cargo.lock files of the project.

$ cargo install --locked cargo-bitbake
$ cd <rust_project_dir>
$ cargo bitbake

This will generate a recipe in the project root which you can use as a starting point.

Example: kantui_git.bb

Note this recipe will only build your Rust crate. To deploy/install your binary you have to define a .inc file with the same name as the recipe that would handle the installation.

Example: kantui.inc

Known bugs

The built-in proc_macros crate is not being imported properly by meta-rust (Kirkstone), thus breaking all library crates that define a proc_macro (meta-rust issue 266). To fix this create a libstd-rs_%.bbappend file containing the single line:

S = "${RUSTSRC}/library/test"

meta-leda already provides this fix here, so it should not be necessary to implement it again.

“Fat” Link time optimization

LTO is a nice feature of LLVM that can optimize even through language boundaries at link-time, but leads to longer overall build times. That is why Rust by default uses “thin” LTO which may result in larger/slower binaries. “Fat” LTO can be enabled when building release binaries by adding to the Cargo.toml file the following section:

[profile.release]
lto = true

For kantui this leads to reduction of the final binary size from ~8 MiB to ~5 MiB.

More information on profile-optimizations can be found here.

Note: Stripping the debug symbols completely results in further binary size reduction, but BitBake fails with a QA problem when deploying stripped binaries.

Rust-based utilities

Utility-Specific Pages