feat(riscv64): add RISC-V build support to devcontainers and CI

Make WASI-SDK installation conditional in both linux and zephyr
Dockerfiles since pre-built binaries are only available for x86_64 and
arm64. Add riscv64-zephyr-elf toolchain to the Zephyr SDK install and
qemu_riscv64 to the Zephyr CI build matrix.

Tested on Banana Pi F3 (SpacemiT K1, rv64gc, 16 GB RAM, Debian Trixie):
all three sample apps (mini, demo, supervisor) build successfully.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Bruno Verachten <gounthar@gmail.com>

Author: gounthar

.devcontainer/linux/Dockerfile

@@ -40,10 +40,17 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && apt-get clean -y\
     && update-alternatives --install /usr/bin/python python /usr/bin/python3 50
 
-# Install wasi-sdk
-RUN mkdir /opt/wasi-sdk && \
-    curl -sSL https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$WASI_SDK_VERSION/wasi-sdk-$WASI_SDK_VERSION.0-$(uname -m | sed s/aarch64/arm64/)-linux.tar.gz | \
-        tar zxvf - --strip-components=1 -C /opt/wasi-sdk
+# Install wasi-sdk (pre-built binaries available for x86_64 and arm64 only)
+RUN ARCH=$(uname -m); \
+    if [ "$ARCH" = "aarch64" ]; then ARCH=arm64; fi; \
+    if [ "$ARCH" = "x86_64" ] || [ "$ARCH" = "arm64" ]; then \
+        mkdir /opt/wasi-sdk && \
+        curl -sSL https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$WASI_SDK_VERSION/wasi-sdk-$WASI_SDK_VERSION.0-${ARCH}-linux.tar.gz | \
+            tar zxvf - --strip-components=1 -C /opt/wasi-sdk; \
+    else \
+        mkdir -p /opt/wasi-sdk; \
+        echo "WASI-SDK not available for $(uname -m), skipping (use -DOCRE_BUILD_DEMO_CONTAINERS=OFF)"; \
+    fi
 
 FROM ocre-ci AS ocre-dev
 

.devcontainer/zephyr/Dockerfile

@@ -51,10 +51,17 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && apt-get clean -y\
     && update-alternatives --install /usr/bin/python python /usr/bin/python3 50
 
-# Install wasi-sdk
-RUN mkdir /opt/wasi-sdk && \
-    curl -sSL https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$WASI_SDK_VERSION/wasi-sdk-$WASI_SDK_VERSION.0-$(uname -m | sed s/aarch64/arm64/)-linux.tar.gz | \
-        tar zxvf - --strip-components=1 -C /opt/wasi-sdk
+# Install wasi-sdk (pre-built binaries available for x86_64 and arm64 only)
+RUN ARCH=$(uname -m); \
+    if [ "$ARCH" = "aarch64" ]; then ARCH=arm64; fi; \
+    if [ "$ARCH" = "x86_64" ] || [ "$ARCH" = "arm64" ]; then \
+        mkdir /opt/wasi-sdk && \
+        curl -sSL https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$WASI_SDK_VERSION/wasi-sdk-$WASI_SDK_VERSION.0-${ARCH}-linux.tar.gz | \
+            tar zxvf - --strip-components=1 -C /opt/wasi-sdk; \
+    else \
+        mkdir -p /opt/wasi-sdk; \
+        echo "WASI-SDK not available for $(uname -m), skipping (use -DOCRE_BUILD_DEMO_CONTAINERS=OFF)"; \
+    fi
 
 RUN python -m venv /opt/zephyr-venv && \
     . /opt/zephyr-venv/bin/activate && \
@@ -78,7 +85,8 @@ RUN . /opt/zephyr-venv/bin/activate && \
     west sdk install --install-base /opt -t \
         x86_64-zephyr-elf \
         aarch64-zephyr-elf \
-        arm-zephyr-eabi
+        arm-zephyr-eabi \
+        riscv64-zephyr-elf
 
 FROM base AS ocre-ci
 

.github/workflows/zephyr.yml

@@ -27,6 +27,7 @@ jobs:
           - pico_plus2/rp2350b/m33
           - native_sim/native/64
           - b_u585i_iot02a
+          - qemu_riscv64
         app:
           - mini
           - demo