Embedded Working Group Meeting 2024-05-14

# Embedded Working Group Meeting 2024-05-14 * [Coordination Repository] * Meetings: Tuesday 8pm Europe/Berlin time * [Join the Chat] * Today's date: 2024-05-14 * [Nominated issues](https://github.com/search?q=org%3Arust-embedded+label%3Anominated+is%3Aopen&type=Issues) * [Discussion topic](https://github.com/rust-embedded/wg/discussions/747) * [IRC logs] [Coordination Repository]: https://github.com/rust-embedded/wg [Join the Chat]: https://matrix.to/#/#rust-embedded:matrix.org [IRC logs]: https://libera.irclog.whitequark.org/rust-embedded/2024-05-14 ## Attendance Write your GH username or Matrix handle here! * adamgreig * dirbaio * jamesmunns * Adam Hott * hdoordt * sirhcel * nastevens * alevy * newAM * therealprof * bartmassey * jannic (late) ## Agenda * Announcements * svd2rust 0.33.3 released * tracking issue to discuss postcard 2.0 https://github.com/jamesmunns/postcard/issues/128 * RustNL recap * https://hackmd.io/p6bQ0OzqTj-R9ra11LvP8A * Roadmap for WG work * Keep working on supported targets and foundational crates like embedded-hal * Improve documentation, tutorials, examples, libraries to ensure many more people can become embedded Rust developers * Improve visibility and discoverability of our work, especially considering specific target audiences * Coordinate with vendors * Ensure we have a good experience for hobbyists coming from platforms such as Arduino, including GUI-only installation experience * Working group meetings and structure * We'd like to remain part of the Rust project and on the whole they'd like something like that too * There's a proposed "Rust Application Organisation" (name TBC) to collect Rust _users_, which we might also become involved in * We should be involved on the Rust Zulip more to improve communication with Project members * Proposal for a new sub-team who are responsible for directly interacting with the Rust Project and have a weekly meeting on Zulip (maybe not every week, depending on what topics come up) * Use of volatilecell and PAC singletons * We need to stop using vcell, move svd2rust and cortex-m to chiptool-style pointers in structs which generate offsets for register access * Still want to split c-m into PAC/HAL layer (and perhaps -asm) * Concluded to propose removing owned singletons from svd2rust, make this a HAL concern instead * Proposal for new MMIO functionality in Rust itself, e.g. mmio_read/mmio_write on ptr, and in the interim we could emulate this in cortex-m with inline assembly * Also add an mmio_fence function * Rust + Bluetooth * Work in progress on TrouBLE with some tasks assigned * PAC/Arch/Runtime crate interactions * Agreed on previous plan to make cortex-m-pac-interface with interrupt trait so that PACs don't have to depend on arch or runtime crates * Looked at how Risc-V is split (-pac, -peripheral, -, -rt) * Discussed interrupt macro syntax options to be able to separate it from the PACs, current conclusion is something like `#[interrupt(pac::Interrupt::UART0)] fn foo() {}` * Binary data structure representations * Documentation * Discussed a plan (see hackmd link above) for discovery book: * Split and archive the old f3disco and mb1 books * Pros * Prevents creating new issues for the old books * Cons * Is there actually a need for maintaining the older books? * What about just keeping them (along with their issues) "archived" (issues closed) in the same repo? * In combination with hosting the older books as-is (see below) * Update current book for full mb2 * Discussed having a simple BSP that's part of the book (or its own crate) to keep the first examples easy, moving to direct HAL use later in the book * Might be able to obtain funding to pay students to help with some chapters * Need better CI * Also want to create a new FAQ page with common questions * We should check where else users are asking questions, such as Discourse * HAL reference examples * Probe-rs * Lots of things to work on and roadmap items planned, see doc for details * Discussed embedded pain points with Rust project * Future of static mut * We discussed the `grounded` crate * Rust wants to more or less deprecate the use of static mut, it already generates a warning and will be forbidden in the 2024 edition * `grounded` offers some well-documented wrappers for many common use cases * We decided to keep developing/documenting grounded as-is for the immediate time being, with a plan to move it into the wg libs team soon, and potentially see some structs move into Rust itself later * Binary code size discussion * Various code size pain points discussed * RFC opened to add a new flag to std allowing size optimisations * Embedded HAL * Documentation * Discovery book * Issues [#568](https://github.com/rust-embedded/discovery/issues/568) & [#567](https://github.com/rust-embedded/discovery/issues/567) * Permission to resources team for @hdoordt and @bartmassey? * https://github.com/rust-embedded/wg/pull/756 * Keeping the previous books hosted? * Pros * Keeping these variants still easily accessible * Catching unknown links under https://docs.rust-embedded.org/discovery/, tell about the new book and still guide to the older variants * Being friendly and not letting aspiring Rust embedded devs with already some cognitive load on their journey just hit a 404 wall * Cons * Some work for embedded WG * Referencing known-good documentation for architectures not covered in the book like std-sync and std-async (on ESP32) * See for example https://github.com/rust-embedded/discovery/pull/559 * Providing some guidance in contrast somewhat somewhat overwhelming _Awesome Embedded Rust_ for beginners * Actions-rs deprecated for GitHub Actions * Issue [#754](https://github.com/rust-embedded/wg/issues/754) * Do we need separate issues per-repo, or "just do it"? * Preferences for rust-toolchain versus just rustup? * Anything (checks, dependabot, etc) that should be included/excluded from all repos? * Decided nastevens will go through repos currently on actions-rs and do simple migration * Then use what's learned from this migration to propose CI template if it makes sense * risc-v CSR access unsafe or not? https://github.com/rust-embedded/riscv/issues/209 ## Last Week's Minutes * Announcements * embedded-hal-bus 0.2 released with AtomicDevice * Target docs for thumb targets PR underway: https://github.com/rust-lang/rust/pull/124404 * @thejpster stepping down from wg and leadership council * next week's meeting is skipped, resuming the week after (on 14th may) * Embedded HAL * AtomicDevice use of portable_atomic means build fails on armv6 https://github.com/rust-embedded/embedded-hal/issues/598 * add atomic-device feature, enable AtomicDevice if feature is enabled or cfg(target_has_atomic..), add atomic-critical-section and atomic-unsafe-assume-single-core (or portable-atomic-...?) which proxy to p-a and also enable atomic-device, document this, release as 0.3 * Tooling docs update: https://github.com/CodingInGreen/tooling * what to add? * Maintenance of STM32 Discovery Book? * Is our most complete book * Does not seem to be in widespread use anymore * Board has changed version * Two books is a lot * Conclusion: don't worry about the stm32 book, mark it as more clearly archived/read-only/deprecated

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