add support for cross-compiling for RVA23

.github/workflows/rva23.yml

@@ -0,0 +1,25 @@
+name: Cross-compile to RVA23
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build image
+      run: podman build -t odorobo-builder:rva23 .
+    - name: Build binaries
+      run: podman run --rm -v ${{ github.workspace }}:/code -w /code odorobo-builder:rva23 cargo build --release
+    - name: Upload artifact
+      uses: actions/upload-artifact@v4
+      with:
+        name: odorobo
+        path: target/riscv64a23-unknown-linux-gnu/release/odorobo

Containerfile

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+FROM alpine:3.23.3
+RUN <<EOF
+apk add \
+	bash \
+	gcc \
+	musl-dev \
+	rustup \
+	zig
+rustup-init \
+	--profile minimal \
+	--target riscv64a23-unknown-linux-gnu \
+	-y
+EOF
+ENV CARGO_BUILD_TARGET="riscv64a23-unknown-linux-gnu"
+ENV PATH="/root/.cargo/bin:$PATH"
+ENV CC_riscv64a23_unknown_linux_gnu="/code/scripts/zig-cc-rva23.sh"
+ENV CARGO_TARGET_RISCV64A23_UNKNOWN_LINUX_GNU_RUSTFLAGS="-C linker=scripts/zig-cc-rva23.sh"

scripts/zig-cc-rva23.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# A script for cargo to use as the C compiler and linker when building RVA23
+# binaries. This links them using zig cc.
+
+args=()
+for arg in "$@"; do
+	case "$arg" in
+	--target=riscv64-unknown-linux-gnu)
+		;;
+	*)
+		args+=("$arg")
+		;;
+	esac
+done
+exec zig cc -target riscv64-linux-gnu "${args[@]}"