can't find crate for `panic_abort`

[kellerkindt]

Hi there,

first of all, I really appreciate your work on rust and the esp controllers! It'll be amazing, once this runs smoothly with the stdlib, thanks a lot!

So, I tried to compile and flash this project onto a ESP32-C3-32S, which is detected via espflash

Chip type:         ESP32-C3 (revision 3)
Crystal frequency: 40MHz
Flash size:        4MB
Features:          WiFi
MAC address:       xx:xx:xx:xx:xx:xx

I cloned this project, changed the target in .cargo/config.tomlto riscv32imc-esp-espidf and tried to compile it, but that does not seem to work:

$ RUST_ESP32_STD_DEMO_WIFI_SSID=ABC RUST_ESP32_STD_DEMO_WIFI_PASS=DEF cargo +nightly build -Z build-std

...

   Compiling embedded-svc v0.12.0
   Compiling esp-idf-sys v0.24.4
   Compiling esp-idf-hal v0.23.3
   Compiling esp-idf-svc v0.28.1
   Compiling rust-esp32-std-demo v0.20.2 (/tmp/rust-esp32-std-demo)
error[E0463]: can't find crate for `panic_abort`

For more information about this error, try `rustc --explain E0463`.
error: could not compile `rust-esp32-std-demo` due to previous error

$ rustc --version
rustc 1.56.1 (59eed8a2a 2021-11-01)
$ rustc +nightly --version
rustc 1.58.0-nightly (495322d77 2021-11-08)

Sooo... what silly mistake am I doing? :)

[ivmarkov]

Sooo... what silly mistake am I doing? :)

-Z build-std

Remove this from the build command line and it should work. -Z build_std and a few build_std_features are already passed to the build command via .cargo/config.toml. Your manual override with -Z build_std is overriding the build_std_features that need to be passed as well with empty ones, as well as not passing ,panic_abort, and hence your build fails.

[ivmarkov]

If you are wondering, -Zbuild_std is compiling by default with a panic_unwind strategy, which will never be supported on the ESP32. We need panic_abort instead. Moreover (for now), we need the panic_immediate_abort behavior of the panic_abort crate, as without it, panic_abort tries to dump a backtrace before panic-ing, which is also not (yet) supported for the esp32 and hence leads to a crash while a crash (panic) is already in progress. And the backtrace (or as you'll soon see - the stack memory dump on esp32c3) is anyways printed by the esp32 native panic handler which triggers always.

[kellerkindt]

Uff, thats a silly one. I tried cargo build previously but not cargo +nightly build :facepalm:

$ RUST_ESP32_STD_DEMO_WIFI_SSID=ABC RUST_ESP32_STD_DEMO_WIFI_PASS=DEF cargo +nightly espflash /dev/ttyUSB0

and

$ espmonitor

now works as well, nice. Any ETA for ESP32-C3 projects on stable?

Thanks!

[ivmarkov]

Any ETA for ESP32-C3 projects on stable?

"ETA for ESP32-C3 projects on stable" = "ETA for cargo -Z build-std on stable".

Seriously. The only reason we are on nightly is because -Z build-std is a nightly-only thing. The STD support for ESP-IDF itself has hit stable since 1.56.

If you have a brilliant idea how to bring functionality similar to -Z build-std to stable, I'm all ears. A solution might be shipping somehow prepackaged core/libstd components for our riscv32imc-esp-espidf target. Since this target is Tier3, Rust upstream does not ship (nor test & compile) these.

[ivmarkov]

By the way, using the Espressif-provided esp toolchain is the closest you get to Rust stable, as these are branched off from the same Rust upstream commit that is used to release/branch the corresponding upstream Rust stable release.

[kellerkindt]

Seriously. The only reason we are on nightly is because -Z build-std is a nightly-only thing. The STD support for ESP-IDF itself has hit stable since 1.56.

Yeah, I saw that release note, which is why I am testing it now :)

Since this target is Tier3, Rust upstream does not ship (nor test & compile) these.

~The naive approach would then be to try to promote it to Tier2? ^^ Tbh, since espressif controllers are quite widespread, one could argue that the riscv version will be relevant soon as well. But I am not familiar with the promotion process at all, so no idea how laborious this would actually be...~

Never mind, this does not seem realistic atm