Rust ESP32 Community Meeting 2021-07-20

[georgik]

(Migrated from archive espressif/rust)

georgik:

Let's discuss topics related to Rust.
Please add topics and links to this discussion.

---

ivmarkov:

Some weekend action + topics/action items for discussion:

• Rust STD fork

  • The patch of @igrr where the atomics are emulated via an invalid instruction exception handler trap is accommodated in esp-idf-sys - against ESP-IDF V4.3 - and in the Rust fork itself via a new ESP32-C3 target. We are still supporting the old story though, with rustc issuing atomics libcalls. This is our story for ESP32-S2 currently.
    • Action item: Discuss the long-term atomics approach for ESP32-S2
  • Proposal for naming the ESP-IDF targets in Rust
    • Action item: Take a decision, so that we can start submitting the Rust STD patches for review to get early feedback from the Rust maintainers

• Hosting the Rust compiler fork GitHub repo

  • Action item: Take a decision - choose espressif or esp-rs org

• esp-idf-sys (the SYS crate providing unsafe bindings to ESP-IDF, which powers esp-idf-hal and esp-idf-svc) is now published to crates.io. Many thanks to @sapir for letting me use his original esp-idf-sys name in crates.io!

  • Action item: Ideally we should host this crate either in the espressif or esp-rs org, because it is key to any Rust development for ESP-IDF

• esp-idf-hal (the HAL crate implementing Rust's "standard" emvedded-hal driver traits on top of the ESP-IDF) is also now published to crates.io. Again, many thanks to @sapir for letting me use his original esp-idf-hal name in crates.io.

  • Action item: Ditto - ideally we should host this crate either in the espressif or esp-rs org, because it is key to any Rust development for ESP-IDF

• esp-idf-svc and embedded-svc also published to crates.io. These are generic traits + ESP-IDF-specific implementation for stuff which belongs neither to esp-idf-hal, nor to the Rust STD fork - for example, APIs & implementations for configuring WiFi; bindings of ESP-IDF logging to Rust's log crate etc. etc.

  • Action item: Ideally we should host these two crates either in the espressif or esp-rs org

• Low prio, only if time permits: would be good to start thinking about Rust support for the ULP RISCV chip in ESP32-S2

  • Action item: Exact riscv architecture? Check if already supported by stock Rust.
  • Of course: no_std and no-alloc. Would be good if core is still supported though
  • Good to have: a Rust "ulp-hal" story/feature in esp-idf-hal implementing the gpio traits from Rust embedded-hal, similar to this C-based code.

---

MabezDev:

Rust STD fork

Notes written up in the proposal issue.

Hosting the Rust compiler fork GitHub repo

Hosted under esp-rs, I moved my fork (as it as the most searchability) there - we will need to rebase on top of @ivmarkov's patches & update readme's etc.

esp-idf-sys, esp-idf-hal

Slight hesitation given that it relies on another external tool (platformio) but I think it will be good to get these moved into esp-rs. The great work by @ivmarkov shows PoC cargo first and idf first approaches solved using this. We can always work on moving away from platformio to just cargo build scripts or integration with idf.py if we need to.

esp-idf-svc and embedded-svc

Happy to move to esp-rs, the embedded hal moves far to slowly to try and upstream this sort of thing there.

---

georgik:

• Supported Linux distro

  • Installation steps for Ubuntu 18 works also for OpenSUSE ThumbleWeed - https://github.com/espressif/rust-esp32-example/blob/main/docs/rust-on-xtensa-installation-x86_64-unknown-linux-gnu-bionic.md

• LLVM

  • CI Build of version 12 with clang is in porgress. We expect new binary artifact from CI this week.

• SVD

  • beta of ESP32-C3 - https://github.com/espressif/svd/tree/esp32c3

• Rust build

  • official Rust distro: sccache, not by GitHub action
  • evaluation using GitHub Action with Matrix.OS for custom build: https://github.com/georgik/idf-rust-build/blob/main/.github/workflows/build-idf-rust.yaml