Hello Genodians

Benjamin Lamowskis great article "A first complex Rust package" [1] and the attention Rust on Genode received recently on this mailing list motivated me to explore the latest achievements regarding Goa and Rust myself :)

I went straight down experimenting with Rocket, a web framework for Rust and setup a corresponding Goa project [2].

Compiling the "Hello World" example [3] with Goa was a very pleasing experience and at link stage, only two symbols were missing: kqueue and kevent. I added dummy implementations for both calls [4] (and by the way learned about the compat-libc API). Building succeeds now, but obviously fails at runtime: ``` Genode 24.02 <local changes> 17592186044415 MiB RAM and 18997 caps assigned to init [init -> hello_rocket] Warning: Libc RNG not configured [init -> hello_rocket] Warning: __sys_kqueue: kqueue not implemented [init -> hello_rocket] thread 'main' panicked at /home/wonko/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rocket-0.5.0/src/lib.rs:245:10: [init -> hello_rocket] create tokio runtime: Os { code: 78, kind: Unsupported, message: "Function not implemented" } [init -> hello_rocket] note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace [init -> hello_rocket] Error: raise(ABRT) [init] child "hello_rocket" exited with exit value -1 ```

I'm aware that most certainly, there are other roadblocks ahead. However, I'd like to pursue the topic regarding kqueue()/kevent() a bit more since I assume this might be (or has been) a roadblock for porting other applications or runtimes.

- Is it reasonable to add those calls to Genodes libc?

- Or can Rust be instructed not to use those calls but select() instead? I stumbled over the MIO flags `mio_unsupported_force_poll_poll` and `mio_unsupported_force_waker_pipe` [5]. But I'm not versed in Rust and setting `mio_unsupported_force_poll_poll` by naively applying the following patch to Goa leads to `error[E0252]: the name `Waker` is defined multiple times`: ``` diff --git a/share/goa/lib/build/cargo.tcl b/share/goa/lib/build/cargo.tcl index 7c0c52b..78e7e26 100644 --- a/share/goa/lib/build/cargo.tcl +++ b/share/goa/lib/build/cargo.tcl @@ -43,6 +43,8 @@ proc build { } { lappend rustflags -C link-arg=$x }

+ lappend rustflags --cfg mio_unsupported_force_poll_poll + set ::env(RUSTFLAGS) $rustflags set ::env(RUST_STD_FREEBSD_12_ABI) 1 ```

- [1] https://genodians.org/atopia/2023-10-26-a-first-complex-rust-package - [2] https://github.com/rite/goa-projects/tree/hello_rocket - [3] https://rocket.rs/guide/v0.5/getting-started - [4] https://github.com/rite/genode/commit/0219d0543cedd180b082e1ef13dd5d779d7e57... - [5] https://github.com/tokio-rs/mio?tab=readme-ov-file#unsupported-flags