Archlinux Rust for ESP(xtensa)

provide PKGBUILD for MabezDev/rust-xtensa

How to build rust toolchain

• download this repo and unzip, click this
• cd rust
• makepkg -s
• pacman -U rust-xtensa-git-*.pkg.tar.zst

This will build rust toolchain and llvm and install it. You will need at least 10GB ram and 25GB disk to build.

For more about build, refer to MabezDev/rust-xtensa

As MabezDev/rust-xtensa update llvm upstream to espressif, the llvm directory is no longer requried, you can still build llvm-project yourself, and add --llvm-root=/opt/llvm-xtensa to rust/PKGBUILD, but this will break install due to the lack of libunwind source code in src/llvm-project/libunwind, you will need to fix it.

Prebuilt

Download from release.

There is no guarantee that prebuilt package will work due to archlinux update policy. If you encounter error, try build yourself or open an issue.

How to use toolchain

This package will install rust toolchain and cargo in /opt/rust-xtensa, you can call cargo and rustc directly from /opt/rust-xtensa/bin.

Or link to rustup:

rustup toolchain link xtensa /opt/rust-xtensa

And call with cargo +xtensa build or override using rustup override set xtensa.

To build to xtensa, use xtensa-esp32-none-elf/xtensa-esp32s2-none-elf/xtensa-esp8266-none-elf target.

Option 1, cargo-xbuild

Install cargo-xbuild with cargo install cargo-xbuild, this tool will help you to compile crate like core, alloc to xtensa target.

example

export XARGO_RUST_SRC=/opt/rust-xtensa/lib/rustlib/src/rust/library
cargo xbuild --target xtensa-esp32-none-elf

Option 2, cargo unstable build-std

Cargo also have a unstable feature build-std, works similar to cargo-xbuild.

example

cargo build -Z build-std --target xtensa-esp32-none-elf

NOTE build-std doesn't work for esp8266 target, but work fine for esp32 and esp32s2

Tips

1. add #![no_std] to your lib.rs or main.rs.

2. #![no_std] doesn't meant to the end of world, you can still use extern crate core to add core library to your crate.

3. add a panic handler, for examples, panic-abort/panic-halt.

4. if you need alloc feature, like vec, add extern crate alloc, and you will need to provide a GlobalAlloc, impl it or find a crate. In my project, i impl it like this:

   use core::alloc::{GlobalAlloc, Layout};
   
   mod ffi {
       extern "C" {
           pub fn malloc(size: usize) -> *mut u8;
       
           pub fn free(ptr: *mut u8);
       }
   }
   
   pub struct IdfAlloc;
   
   unsafe impl GlobalAlloc for IdfAlloc {
       unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
           ffi::malloc(layout.size())
       }
   
       unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
           ffi::free(ptr);
       }
   }
   
   #[global_allocator]
   static ALLOC: IdfAlloc = IdfAlloc;

   this need link to newlib of esp-idf to work.

5. For API like wifi, bluetooth, GPIO, i just write ffi bindings to esp-idf and link to them.