Add RISC-V smoke test on QEMU

.ci/scripts/test_riscv_qemu.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# Copyright 2026 The ExecuTorch Authors.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# CI wrapper: install RISC-V cross-compile + qemu-user tooling, then run the
+# RISC-V Phase 1 smoke test (export, cross-compile, qemu-user execution) via
+# examples/riscv/run.sh. The bundled-IO comparison and Test_result: PASS
+# check are done by run.sh.
+
+set -eu
+
+script_dir=$(realpath "$(dirname "${BASH_SOURCE[0]}")")
+et_root_dir=$(realpath "${script_dir}/../..")
+
+bash "${et_root_dir}/examples/riscv/setup.sh"
+bash "${et_root_dir}/examples/riscv/run.sh"

.github/workflows/_test_riscv.yml

@@ -0,0 +1,32 @@
+name: Test RISC-V QEMU smoke
+
+permissions:
+  id-token: write
+  contents: read
+
+on:
+  workflow_call:
+    inputs:
+      timeout:
+        description: 'Per-job timeout in minutes'
+        required: false
+        type: number
+        default: 30
+
+jobs:
+  run:
+    uses: pytorch/test-infra/.github/workflows/linux_job_v2.yml@main
+    with:
+      runner: linux.2xlarge
+      docker-image: ci-image:executorch-ubuntu-22.04-gcc11
+      submodules: 'recursive'
+      ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      timeout: ${{ inputs.timeout }}
+      script: |
+        CONDA_ENV=$(conda env list --json | jq -r ".envs | .[-1]")
+        conda activate "${CONDA_ENV}"
+
+        source .ci/scripts/utils.sh
+        install_executorch "--use-pt-pinned-commit"
+
+        bash .ci/scripts/test_riscv_qemu.sh

.github/workflows/riscv64.yml

@@ -0,0 +1,30 @@
+name: RISC-V
+
+on:
+  push:
+    branches:
+      - main
+      - release/*
+    tags:
+      - ciflow/trunk/*
+  pull_request:
+    paths:
+      - .github/workflows/riscv64.yml
+      - .ci/scripts/test_riscv_qemu.sh
+      - tools/cmake/preset/riscv64_linux.cmake
+      - examples/riscv/**
+  workflow_dispatch:
+  schedule:
+    - cron: '0 10 * * *'  # Runs daily at 2 AM PST
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}-${{ github.event_name == 'workflow_dispatch' }}-${{ github.event_name == 'schedule' }}
+  cancel-in-progress: true
+
+jobs:
+  test-riscv:
+    name: test-riscv
+    uses: ./.github/workflows/_test_riscv.yml
+    permissions:
+      id-token: write
+      contents: read

.gitignore

@@ -9,6 +9,7 @@ __pycache__/
 
 # Build and tool-generated files
 arm_test/
+riscv_test/
 buck-out/
 buck2-bin/
 build/

CMakePresets.json

@@ -313,6 +313,20 @@
         "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/examples/arm/ethos-u-setup/aarch64-linux-musl-toolchain.cmake"
       }
     },
+    {
+      "name": "riscv64-linux",
+      "displayName": "Build ExecuTorch for riscv64 Linux (cross-compile)",
+      "inherits": ["common"],
+      "cacheVariables": {
+        "EXECUTORCH_BUILD_PRESET_FILE": "${sourceDir}/tools/cmake/preset/riscv64_linux.cmake",
+        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/examples/riscv/riscv64-linux-gnu-toolchain.cmake"
+      },
+      "condition": {
+        "lhs": "${hostSystemName}",
+        "type": "equals",
+        "rhs": "Linux"
+      }
+    },
     {
       "name": "mlx",
       "displayName": "Build MLX delegate",

examples/riscv/README.md

@@ -0,0 +1,41 @@
+# RISC-V
+
+Cross-compile `executor_runner` for `riscv64-linux-gnu` and run it under
+`qemu-user-static` against a small bundled program. The end-to-end check
+mirrors the Arm Cortex-M e2e flow: a `Test_result: PASS` line in stdout from
+the bundled-IO comparison path is the pass criterion.
+
+This is the Phase 1 deliverable for the RISC-V Support RFC at
+[pytorch/executorch#18991][rfc]. The cross-compile and runner artifacts
+(toolchain file, preset, AOT script) are designed to carry over unchanged
+to a hardware-runner job once one becomes available; only the invocation
+step (qemu-user vs. native) would change.
+
+[rfc]: https://github.com/pytorch/executorch/issues/18991
+
+## Quick start (Ubuntu / Debian)
+
+```bash
+examples/riscv/setup.sh        # apt: gcc-riscv64-linux-gnu, qemu-user-static
+examples/riscv/run.sh          # export, cross-compile, run under qemu-user
+```
+
+The driver does three steps:
+
+1. `python examples/riscv/aot_riscv.py` exports a `torch.add` module to
+   `riscv_test/add_riscv.bpte` (a BundledProgram with reference outputs
+   embedded for two test cases).
+2. `cmake --preset riscv64-linux` configures the cross-build using
+   `examples/riscv/riscv64-linux-gnu-toolchain.cmake` and
+   `tools/cmake/preset/riscv64_linux.cmake`. `executor_runner` is built
+   against portable kernels with `ET_BUNDLE_IO_ENABLED` defined.
+3. `qemu-riscv64-static` invokes the runner with `--model_path` pointing at
+   the `.bpte`. The runner detects the bundle, runs every embedded test case,
+   and emits `Test_result: PASS` (or `FAIL`) per case.
+
+## CI
+
+`.github/workflows/_test_riscv_qemu.yml` is a reusable `workflow_call`
+job (mirroring `_test_cortex_m_e2e.yml`) invoked from `pull.yml` to run on
+every PR. It runs on the standard `linux.2xlarge` x86_64 runner using the
+`executorch-ubuntu-22.04-gcc11` docker image.

examples/riscv/aot_riscv.py

@@ -0,0 +1,68 @@
+# Copyright 2026 The ExecuTorch Authors.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""AOT export for the RISC-V Phase 1.0 smoke test.
+
+Exports a trivial ``torch.add`` module to a BundledProgram (.bpte) that the
+portable executor_runner can load on a riscv64 target and verify against the
+embedded reference output, emitting ``Test_result: PASS`` on success.
+"""
+
+import argparse
+from pathlib import Path
+
+import torch
+from executorch.devtools import BundledProgram
+from executorch.devtools.bundled_program.config import MethodTestCase, MethodTestSuite
+from executorch.devtools.bundled_program.serialize import (
+    serialize_from_bundled_program_to_flatbuffer,
+)
+from executorch.exir import to_edge_transform_and_lower
+from torch.export import export
+
+
+class AddModule(torch.nn.Module):
+    def forward(self, x: torch.Tensor, y: torch.Tensor) -> torch.Tensor:
+        return x + y
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--output",
+        type=Path,
+        default=Path("add_riscv.bpte"),
+        help="Output .bpte path",
+    )
+    args = parser.parse_args()
+
+    model = AddModule().eval()
+    example_inputs = (torch.ones(1, 4), torch.full((1, 4), 2.0))
+
+    exported = export(model, example_inputs)
+    et_program = to_edge_transform_and_lower(exported).to_executorch()
+
+    test_inputs = [
+        (torch.ones(1, 4), torch.full((1, 4), 2.0)),
+        (torch.full((1, 4), 3.0), torch.full((1, 4), 4.0)),
+    ]
+    test_suite = MethodTestSuite(
+        method_name="forward",
+        test_cases=[
+            MethodTestCase(inputs=inp, expected_outputs=(model(*inp),))
+            for inp in test_inputs
+        ],
+    )
+
+    bundled = BundledProgram(et_program, [test_suite])
+    serialized = serialize_from_bundled_program_to_flatbuffer(bundled)
+
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    args.output.write_bytes(serialized)
+    print(f"Wrote {args.output} ({len(serialized)} bytes)")
+
+
+if __name__ == "__main__":
+    main()

examples/riscv/riscv64-linux-gnu-toolchain.cmake

@@ -0,0 +1,40 @@
+# Copyright 2026 The ExecuTorch Authors.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# CMake toolchain file for cross-compiling to riscv64 Linux glibc using the
+# Ubuntu / Debian gcc-riscv64-linux-gnu and g++-riscv64-linux-gnu packages.
+# Resulting binaries can be executed under qemu-user-static (qemu-riscv64) or
+# directly on a riscv64 Linux host.
+
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR riscv64)
+
+set(CMAKE_C_COMPILER
+    "riscv64-linux-gnu-gcc"
+    CACHE FILEPATH "RISC-V cross C compiler"
+)
+set(CMAKE_CXX_COMPILER
+    "riscv64-linux-gnu-g++"
+    CACHE FILEPATH "RISC-V cross C++ compiler"
+)
+set(CMAKE_AR
+    "riscv64-linux-gnu-ar"
+    CACHE FILEPATH "RISC-V archiver"
+)
+set(CMAKE_RANLIB
+    "riscv64-linux-gnu-ranlib"
+    CACHE FILEPATH "RISC-V ranlib"
+)
+set(CMAKE_STRIP
+    "riscv64-linux-gnu-strip"
+    CACHE FILEPATH "RISC-V strip"
+)
+
+# Sysroot installed by the apt package gcc-riscv64-linux-gnu.
+set(CMAKE_FIND_ROOT_PATH "/usr/riscv64-linux-gnu")
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

examples/riscv/run.sh

@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+# Copyright 2026 The ExecuTorch Authors.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# RISC-V Phase 1 smoke test driver (pytorch/executorch#18991):
+#   1. Export a tiny model to a BundledProgram (.bpte) on the x86_64 host.
+#   2. Cross-compile executor_runner for riscv64 Linux glibc.
+#   3. Invoke the runner under qemu-user-static and grep its stdout for the
+#      Test_result: PASS marker emitted by the bundled-IO comparison path.
+
+set -eu
+
+script_dir=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &> /dev/null && pwd)
+et_root_dir=$(realpath "${script_dir}/../..")
+
+build_only=false
+build_dir="${et_root_dir}/cmake-out-riscv"
+output_dir="${et_root_dir}/riscv_test"
+qemu="qemu-riscv64-static"
+qemu_timeout="600"
+
+usage() {
+    cat <<EOF
+Usage: $(basename "$0") [options]
+Options:
+  --build_only            Only export and cross-compile; do not invoke QEMU
+  --build_dir=<DIR>       CMake build directory (default: ${build_dir})
+  --output_dir=<DIR>      Directory for the exported .bpte (default: ${output_dir})
+  --qemu=<BIN>            qemu-user binary (default: ${qemu})
+  --timeout=<SECONDS>     Maximum QEMU runtime; matches run_fvp.sh --timelimit (default: ${qemu_timeout})
+  -h, --help              Show this help
+EOF
+}
+
+for arg in "$@"; do
+    case $arg in
+        --build_only) build_only=true ;;
+        --build_dir=*) build_dir="${arg#*=}" ;;
+        --output_dir=*) output_dir="${arg#*=}" ;;
+        --qemu=*) qemu="${arg#*=}" ;;
+        --timeout=*) qemu_timeout="${arg#*=}" ;;
+        -h|--help) usage; exit 0 ;;
+        *) echo "Unknown option: $arg" >&2; usage; exit 1 ;;
+    esac
+done
+
+mkdir -p "${output_dir}"
+bpte_path="${output_dir}/add_riscv.bpte"
+
+echo "[run.sh] Step 1/3: AOT export on host"
+python "${script_dir}/aot_riscv.py" --output "${bpte_path}"
+
+echo "[run.sh] Step 2/3: cross-compile executor_runner for riscv64-linux"
+cmake -S "${et_root_dir}" -B "${build_dir}" \
+    --preset riscv64-linux \
+    -DCMAKE_BUILD_TYPE=Release
+cmake --build "${build_dir}" -j"$(nproc)" --target executor_runner
+
+runner="${build_dir}/executor_runner"
+[[ -x "${runner}" ]] || { echo "[run.sh] runner not found at ${runner}" >&2; exit 1; }
+
+if file "${runner}" | grep -q "RISC-V"; then
+    echo "[run.sh] runner is a RISC-V ELF: $(file -b "${runner}")"
+else
+    echo "[run.sh] ERROR: ${runner} does not look like a RISC-V ELF"
+    file "${runner}"
+    exit 1
+fi
+
+if ${build_only}; then
+    echo "[run.sh] --build_only set, skipping QEMU invocation"
+    exit 0
+fi
+
+echo "[run.sh] Step 3/3: run under ${qemu}"
+hash "${qemu}" 2>/dev/null || {
+    echo "[run.sh] ERROR: ${qemu} not found on PATH; install with examples/riscv/setup.sh" >&2
+    exit 1
+}
+
+# QEMU_LD_PREFIX points qemu-user at the riscv64 sysroot so the dynamic
+# linker (ld-linux-riscv64-lp64d.so.1) referenced in the ELF resolves.
+export QEMU_LD_PREFIX="${QEMU_LD_PREFIX:-/usr/riscv64-linux-gnu}"
+
+log_file=$(mktemp)
+trap 'rm -f "${log_file}"' EXIT
+
+set +e
+timeout --signal=KILL "${qemu_timeout}" "${qemu}" "${runner}" \
+    --model_path="${bpte_path}" \
+    2>&1 | tee "${log_file}"
+qemu_status=${PIPESTATUS[0]}
+set -e
+
+echo "[run.sh] qemu exit status: ${qemu_status}"
+
+if grep -q "Test_result: PASS" "${log_file}"; then
+    echo "[run.sh] Bundled I/O check PASSED"
+    exit 0
+elif grep -q "Test_result: FAIL" "${log_file}"; then
+    echo "[run.sh] ERROR: Bundled I/O check FAILED"
+    exit 1
+else
+    echo "[run.sh] ERROR: No Test_result line found in QEMU output"
+    exit 1
+fi