Add Linux arm64 support to the SDK v2 packaging pipelines by baijumeswani · Pull Request #894 · microsoft/foundry-local

baijumeswani · 2026-07-21T17:24:36Z

Adds first-class Linux arm64 support across the SDK v2 build, test, and packaging pipelines. Every package format the pipeline already produces (C++ tgz, Runtime NuGet, Python wheel, npm tarball) now includes a linux-arm64 payload, built and tested natively on the onnxruntime-linux-ARM64-CPU-2019 pool.

Initial Linux ARM64 support is CPU-only.

vercel · 2026-07-21T17:24:42Z

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Project	Deployment	Actions	Updated (UTC)
foundry-local	Ready	Preview, Comment	Jul 21, 2026 5:24pm

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Pull request overview

Adds native CPU-only Linux ARM64 support across SDK v2 build, test, and packaging workflows.

Changes:

Adds ARM64 native builds and C++, C#, Python, and JavaScript test stages.
Packages Linux ARM64 binaries in C++ archives, NuGet, Python wheels, and npm tarballs.
Updates runtime detection, dependency selection, WebGPU fallback behavior, tests, and documentation.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
`sdk_v2/python/test/unit/test_lib_loader.py`	Tests ARM64 platform detection.
`sdk_v2/python/test/unit/test_build_backend.py`	Tests dependency-pin rewriting.
`sdk_v2/python/src/foundry_local_sdk/_native/lib_loader.py`	Detects Linux ARM64 payloads.
`sdk_v2/python/pyproject.toml`	Adds CPU-only ARM64 dependencies.
`sdk_v2/python/_build_backend/__init__.py`	Rewrites plain ORT package pins.
`sdk_v2/js/script/install-native.cjs`	Supports ARM64 and fails on missing payloads.
`sdk_v2/cpp/triplets/arm64-linux.cmake`	Defines the ARM64 vcpkg triplet.
`sdk_v2/cpp/test/internal_api/webgpu_ep_bootstrapper_test.cc`	Adds WebGPU bootstrapper tests.
`sdk_v2/cpp/test/CMakeLists.txt`	Registers the new C++ test file.
`sdk_v2/cpp/src/ep_detection/webgpu_ep_bootstrapper.h`	Documents ARM64 WebGPU behavior.
`sdk_v2/cpp/src/ep_detection/webgpu_ep_bootstrapper.cc`	Gracefully disables unavailable ARM64 WebGPU.
`sdk_v2/cpp/nuget/test_pack.py`	Tests NuGet staging and RID mapping.
`sdk_v2/cpp/nuget/pack.py`	Stages the Linux ARM64 runtime.
`sdk_v2/cpp/nuget/Microsoft.AI.Foundry.Local.Runtime.nuspec`	Documents the ARM64 payload.
`sdk_v2/cpp/cmake/FindOnnxRuntimeGenAI.cmake`	Selects ARM64 GenAI binaries.
`sdk_v2/cpp/cmake/FindOnnxRuntime.cmake`	Selects CPU-only ARM64 ORT binaries.
`.pipelines/v2/templates/steps-test-python.yml`	Supports system Python on ARM64 agents.
`.pipelines/v2/templates/steps-test-js.yml`	Enables Linux ARM64 JavaScript tests.
`.pipelines/v2/templates/steps-pack-nuget.yml`	Includes the ARM64 native artifact.
`.pipelines/v2/templates/steps-pack-js.yml`	Merges the ARM64 npm prebuild.
`.pipelines/v2/templates/steps-pack-cpp-sdk.yml`	Produces an ARM64 C++ archive.
`.pipelines/v2/templates/steps-build-python.yml`	Supports ARM64 system Python builds.
`.pipelines/v2/templates/steps-build-linux.yml`	Parameterizes Linux CPU architecture.
`.pipelines/v2/templates/steps-build-js.yml`	Builds and stages ARM64 Node addons.
`.pipelines/v2/templates/stages-python.yml`	Adds ARM64 Python build and test stages.
`.pipelines/v2/templates/stages-js.yml`	Adds ARM64 JavaScript build and test stages.
`.pipelines/v2/templates/stages-cs.yml`	Adds ARM64 C# testing.
`.pipelines/v2/templates/stages-build-native.yml`	Adds native ARM64 build and packaging inputs.
`.pipelines/v2/sdk_v2-pipeline-plan.md`	Documents the expanded pipeline matrix.
`.pipelines/v2/sdk_v2-js-pipeline-plan.md`	Documents ARM64 JavaScript packaging.

    "openai>=2.24.0",
-    "onnxruntime-gpu==0.0.0; platform_system == 'Linux'",
+    "onnxruntime-gpu==0.0.0; platform_system == 'Linux' and platform_machine == 'x86_64'",
+    "onnxruntime==0.0.0; platform_system == 'Linux' and platform_machine == 'aarch64'",


    "onnxruntime-core==0.0.0; platform_system != 'Linux'",
-    "onnxruntime-genai-cuda==0.0.0; platform_system == 'Linux'",
+    "onnxruntime-genai-cuda==0.0.0; platform_system == 'Linux' and platform_machine == 'x86_64'",
+    "onnxruntime-genai==0.0.0; platform_system == 'Linux' and platform_machine == 'aarch64'",


prathikr · 2026-07-21T19:30:44Z

+Run with:
+    python -m unittest test_pack        (from sdk_v2/cpp/nuget/)
+    python test_pack.py                 (direct invocation)


OR, include more comments/details on when this should be run and what the purpose of this testing script is

+// The linux-arm64 "no WebGPU payload" path relies on the compile-time
+// kPlatformKey being "linux-arm64", which causes GetPackageMetadata() to
+// throw at the start of DownloadAndRegister — caught and returned as false.
+// That path can only be exercised on an ARM64 Linux host; the contract is
+// documented by the header comment and the static preprocessor block.


+    def _run_stage(self, rid_arg: str) -> tuple[Path, Path]:
+        """
+        Run pack.stage() with a single platform artifact.
+        Returns (staging_dir, artifact_dir).
+        """


prathikr

Can you add to the PR description all the new unit tests that have been introduced and their purposes?

prathikr · 2026-07-21T19:17:05Z

+  dependsOn:
+  - compute_version
+  - cpp_build_linux_arm64
+  - cpp_build_win_x64


why does this stage depend on win x64?

prathikr · 2026-07-21T19:18:46Z

 # src/foundry_local_sdk/_native/<rid>/). On Windows that native artifact carries
 # the reg-free WinML 2.x runtime, so the single wheel includes WinML support.
 #
+# linux-arm64 is CPU-only; it uses onnxruntime + onnxruntime-genai (plain


can you include why this is the case and what needs to happen in order to enable linux-arm64+gpu support?

prathikr · 2026-07-21T19:21:09Z

+        rid: 'linux-arm64'
+        useSystemPython: true
+        outputDir: '$(Build.ArtifactStagingDirectory)/python-sdk'
+    # Assert the produced wheel has the correct platform tag and bundles the


Is this something we should be doing for all platforms?

prathikr · 2026-07-21T19:28:15Z

+            set(_ORT_LIB_DIR "${ort_gpu_linux_SOURCE_DIR}/runtimes/${_ORT_PLATFORM}/native")
+            message(STATUS "OnnxRuntime GPU Linux package: ${ort_gpu_linux_SOURCE_DIR}")
+        else()
+            # linux-arm64: libonnxruntime.so is included directly in the Microsoft.ML.OnnxRuntime.Foundry


Will this impact our future process for removing the .Foundry package and relying on the plain ort cpu package (once all eps are plugin)?

prathikr · 2026-07-21T19:30:44Z

+Run with:
+    python -m unittest test_pack        (from sdk_v2/cpp/nuget/)
+    python test_pack.py                 (direct invocation)


OR, include more comments/details on when this should be run and what the purpose of this testing script is

prathikr · 2026-07-21T19:31:22Z


 // Platform-specific package metadata is baked into the binary to keep
-// verification inputs fixed at build time.
+// verification inputs fixed at build time. linux-arm64 is intentionally absent


Is the CDN package updated? Might need to do this before merging this PR

baijumeswani added 2 commits July 20, 2026 15:23

Add Linux aarch64 builds

2636fe4

Fix

41a0aad

Copilot AI review requested due to automatic review settings July 21, 2026 17:24

Copilot started reviewing on behalf of baijumeswani July 21, 2026 17:25 View session

Copilot AI reviewed Jul 21, 2026

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prathikr reviewed Jul 21, 2026

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Add Linux arm64 support to the SDK v2 packaging pipelines#894

Add Linux arm64 support to the SDK v2 packaging pipelines#894
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