PAL File for Arm Zephyr Executor Runner

[BujSet]

Summary

Platform file for building Zephyr applications that use Executorch as a module. This is a simplified version of the file used in a Zephyr development branch here.

In the future, it may be prudent to have a PAL file for arm bare metal (I imagine this would require a simple splicing of he PAL functions from the arm_executor_runner.cpp file). Leaving that task for a separate PR.

Test plan

Tested against the arm_executor_runner.cpp that is used in the Arm-EthosU tutorial. Was able to successfully build the Arm Executor Runner, and run the simple add model.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/12348

• 📄 Preview Python docs built from this PR

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❌ 1 New Failure

As of commit 2bab70b with merge base a8070ec ():

NEW FAILURE - The following job has failed:

• pull / test-eval_llama-mmlu-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 4bf9501f068ac8a45fbba96a0c27f6daa42c70f9a9dfa6c6ad42910fd30e7e73 /exec failed with exit code 1

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[BujSet]

@pytorchbot label "release notes: none"

[larryliu0820]

Can you change the zephyr preset to use this file instead of minimal or posix?

[larryliu0820]

Can you change the zephyr preset to use this file instead of minimal or posix?

For this you will have to change override the option: https://github.com/pytorch/executorch/blob/main/tools/cmake/preset/default.cmake#L38C3-L38C35

[BujSet]

Can you change the zephyr preset to use this file instead of minimal or posix?

Hm, is this what we want for the preset? The PAL requires access to the Zephyr library, so if I set this in the preset, the build-preset test will fail unless we build the entire test with zephyr. Similarly, if I make the change to the preset file where I set:

set(EXECUTORCH_PAL_DEFAULT_FILE_PATH              "${PROJECT_SOURCE_DIR}/runtime/platform/default/arm_zephyr.hpp")

The commands from the original zephyr cmake preset PR will error out. What do you think @larryliu0820?

[digantdesai]

No CMake changes?

[BujSet]

No CMake changes?

@digantdesai, kind of the same comment as above in response to Mengwei's question about the preset. The problem is that this file can't be built without linking to an existing zephyr library. To avoid adding zephyr as a dependency, I made the PAL a header file instead of a cpp source file so that it never needs to be built, but can be included when Executorch is built as module of zephyr.

[larryliu0820]

ok I think this is fine, but I really think we should have a CI job in ExecuTorch that:

• install zephyr and executorch as a module of it (you can check out a branch of zephyr)
• compile with arm runner and memory allocator and PAL
• run a hello world example

So maybe we can have a quick followup PR