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Setting up Tensorflow for Windows on Arm

Everton Constantino
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4 mins read
Machine Learning Windows On Arm

Introduction

Tensorflow is one of the major machine learning frameworks used today. It is usually distributed via Python packages built using Bazel. At the time of writing, there is no official package available for Tensorflow to run natively on Windows on Arm. However, to help developers use these tools, this blog post shows how you can build your own Tensorflow package using some patches we developed to do this.

The process starts with setting up the environment, then you build your own Bazel and finally build Tensorflow. We have enabled Bazel for Windows on Arm. The version that the official binary is available in is 5.1.

Unfortunately it is not possible to build our current Tensorflow branch with this version, which is why you will need to build it from source. All the steps were tested on a Surface Pro with Windows 11.

Setup Requirements

nuget.exe install pythonarm64 -Version 3.10.0

NB: This only needs to be done for Python 3.10.0 From 3.11.0a5 onwards official binaries for Windows on Arm can be downloaded. Make sure to add this Python to path.

cmd.exe /c "call `"__PATH__\VC\Auxiliary\Build\vcvarsx86_arm64.bat`" && set > %temp%\vcvars.txt"
Get-Content "$env:temp\vcvars.txt" | Foreach-Object {
  if ($_ -match "^(.*?)=(.*)$") {
    Set-Content "env:\$($matches[1])" $matches[2]
  }
}
$env:PATH+=";_PATH_KIT__\arm64\ucrt\;__PATH__\VC\Redist\MSVC\14.29.30133\onecore\debug_nonredist\arm64\Microsoft.VC142.DebugCRT"

Where PATH is the Visual Studio CE installation path and PATH_KIT the Windows SDK installation path. Finally, grab our patched Tensorflow from https://github.com/everton1984/tensorflow and check out the win_arm64v2 branch.

Building Tensorflow

First you should make sure you have read the guide to compile Tensorflow from source at https://www.tensorflow.org/install/source. Make sure to also install all required Python packages mentioned in it.

The repository you downloaded Bazel from added support for a new cpu/OS x64_arm64_windows and the main change to Tensorflow is to add support for a new target - win_arm64. The patch is experimental and some features have not been tested thoroughly, but the work entailed not only adding the new target but also adapting third party libraries to actually take advantage of it and understand that now you can be compiling on Windows but the CPU is not necessarily x86.

To compile just run:

bazel build –config=win_arm64 //tensorflow/tools/pip_package:build_pip_package

Bazel might fail to properly link with python.3.10.0.lib. If that occurs make sure to copy that file directly into LLVM’s library folder. Once this step is complete, execute the script to build the whl package itself:

./bazel-bin/tensorflow/tools/pip_package/build_pip_package.exe WHL_DIR

This will build the whl on the path pointed by WHL_DIR. You will notice that you won’t be able to install that particular whl because of the lack of a dependency tensorflow_io_gcs_filesystem but you can force the installation with the extra pip argument –no-dependencies.

You can then import tensorflow for your Python scripts.

Limitations

Not all features will work because of a lack of Tensorflow IO for Windows on Arm. Building Tensorflow IO requires a pre-working version of Tensorflow so the bootstrapping process is too complex for this article. Note that without Tensorflow IO several important Tensorflow features will fail to execute.

In order to execute part of Tensorflow’s unit tests you must use bazel’s test command. We examined the ones under core/kernels, and currently only lmdb_dataset_op_test seems to fail. There seems to be a bug in either bazel or LLVM that requires the tests to be built without dynamic libraries, so it is necessary to add an additional argument –dynamic_mode=off.

To execute just the core/kernels test then type

bazel test –config=win_arm64 –dynamic_mode=off //tensorflow/core/kernels/…

At present there are no plans for official native support of Tensorflow on Windows on Arm, but that may change if the community pushes strongly for it

Conclusion

Here we show the process of how to build Tensorflow for Windows on Arm. This has been part of a continuous joint effort between Linaro and Microsoft to provide a smooth native Arm environment for its Surface devices and Azure cloud instances. Feel free to read more about this at https://linaro.org/windows-on-arm.

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