I saw this on the Arm discord from a few weeks ago:

```
Regarding the question about who contributes to Rust on Arm: The standard Rust compiler is built on top of LLVM, so the excellent Arm support is in good part thanks to the LLVM contributors (at Arm and outside). Arm focuses its involvement in the Rust project on (Tier 1) `aarch64-unknown-linux-gnu` target. We are thankful that Arm partners and Rust community members are maintaining other Arm targets (e.g. the Embedded Rust WG maintains the Cortex-M targets https://doc.rust-lang.org/nightly/rustc/platform-support/arm-none-eabi.html).
```