Zephyr: Update to Zephyr 4.4

[zingo]

Update CI install and testing, samples and docs
Zephyr 4.4 also added support for ensemble_e8_dk
so it can be used out of the box instead of the
alif zephyr git fork.

Test plan

Mosted tested by Github CI , Alif readme tested by hand.

cc @digantdesai @freddan80 @per @oscarandersson8218 @mansnils @Sebastian-Larsson @robell @rascani

[pytorch-bot]

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❌ 7 New Failures, 28 Cancelled Jobs

As of commit 95e8d70 with merge base 968fff9 ():

NEW FAILURES - The following jobs have failed:

• pull / test-arm-cortex-m-size-test (zephyr-preset) / linux-job (gh)
  RuntimeError: Command docker exec -t 9f2536aed24adbcfd6d3c237ce6abb14dca5968ef77b6ae75d41731f89dcb280 /exec failed with exit code 2
• trunk / test-arm-backend-zephyr (zephyr/samples/hello-executorch/README.md, cortex-m55) / linux-job (gh)
  RuntimeError: Command docker exec -t 0add8c83c7df402cea7b06db4ea87d33bf31b1a8942ef1b84ce9d772f5137317 /exec failed with exit code 1
• trunk / test-arm-backend-zephyr (zephyr/samples/hello-executorch/README.md, ethos-u55) / linux-job (gh)
  RuntimeError: Command docker exec -t 587119a05fbbcb556aa92d496f6a2e0df1ccc94577ca0dddb74013cd2768dbd6 /exec failed with exit code 1
• trunk / test-arm-backend-zephyr (zephyr/samples/hello-executorch/README.md, ethos-u85) / linux-job (gh)
  RuntimeError: Command docker exec -t 2945568035b579777dec2030becdbdd87df6585f8dc687338f6635f6d88d6f2e /exec failed with exit code 1
• trunk / test-arm-backend-zephyr (zephyr/samples/mv2-ethosu/README.md, ethos-u55) / linux-job (gh)
  RuntimeError: Command docker exec -t 40ddded0543a0a3b49e5bf03598de05e06a49bc682dcdb463eacf4d3984aa3ab /exec failed with exit code 1
• trunk / test-arm-backend-zephyr (zephyr/samples/mv2-ethosu/README.md, ethos-u85) / linux-job (gh)
  RuntimeError: Command docker exec -t 1b76dba92a27efdc0a7960f644915a6be450e1d32f2428a9cab7cd2c8708ddcf /exec failed with exit code 1
• trunk / test-models-macos-coreml (dl3) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
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• pull / unittest / linux / linux-job (gh)
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• pull / unittest-nxp-neutron / linux-job (gh)
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• Test RISC-V Backend / test-riscv (add, false, false) / run / linux-job (gh)
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• Test RISC-V Backend / test-riscv (mv2, false, false) / run / linux-job (gh)
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• Test RISC-V Backend / test-riscv (resnet18, false, false) / run / linux-job (gh)
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• Test RISC-V Backend / test-riscv (resnet18, true, true) / run / linux-job (gh)
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• trunk / test-demo-backend-delegation (buck2) / linux-job (gh)
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• trunk / test-demo-backend-delegation (cmake) / linux-job (gh)
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• trunk / test-models-linux-aarch64 (ic4, portable, linux.arm64.2xlarge) / linux-job (gh)
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• trunk / test-models-linux-aarch64 (phi_4_mini, portable, linux.arm64.m7g.4xlarge) / linux-job (gh)
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• trunk / unittest-release / linux / linux-job (gh)
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[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Copilot / name: Copilot Autofix powered by AI (11b9daa, 61d6819, bcf6a0b)
• ✅ login: zingo / name: Zingo Andersen (a6a7a36, 11b9daa, 61d6819, bcf6a0b)

[Copilot]

Pull request overview

Updates the ExecuTorch Zephyr integration to target Zephyr v4.4.0, refreshes the Zephyr setup flow used by CI/docs, and adds out-of-the-box support for the ensemble_e8_dk Alif E8 board variants.

Changes:

• Bump Zephyr manifest revision to v4.4.0 and switch setup docs/CI to west packages pip --install + west sdk install.
• Update Zephyr sample docs (FVP + Alif E8) and tutorials for Python 3.12+, new board naming, and improved flashing/run instructions.
• Improve Zephyr CI setup: shared workspace directory (zephyr_dev_root) and a local Zephyr SDK releases proxy fallback to mitigate rate limits/network flakiness.

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
zephyr/samples/mv2-ethosu/README.md	Updates prerequisites (Python 3.12+), FVP env vars, and Alif E8 build/flash/run instructions.
zephyr/samples/mv2-ethosu/boards/ensemble_e8_dk_ae822fa0e5597ls0_rtss_hp.overlay	New DTS overlay to expose a larger contiguous SRAM region and enable Ethos-U for RTSS-HP.
zephyr/samples/mv2-ethosu/boards/ensemble_e8_dk_ae822fa0e5597ls0_rtss_hp.conf	New board config enabling Ethos-U and DMA-accessible PTE handling (HP).
zephyr/samples/mv2-ethosu/boards/ensemble_e8_dk_ae822fa0e5597ls0_rtss_he.overlay	New DTS overlay for RTSS-HE (larger SRAM + Ethos-U node).
zephyr/samples/mv2-ethosu/boards/ensemble_e8_dk_ae822fa0e5597ls0_rtss_he.conf	New board config enabling Ethos-U and DMA-accessible PTE handling (HE).
zephyr/samples/mv2-ethosu/boards/alif_e8_dk_ae822fa0e5597xx0_rtss_hp.conf	Removes old Alif E8 board config in favor of upstream ensemble_e8_dk.
zephyr/samples/hello-executorch/README.md	Adds safer LD_LIBRARY_PATH export for FVP usage.
zephyr/README.md	Updates to Zephyr 4.4 and adds explicit west packages + west sdk install steps (used by CI).
docs/source/zephyr_alif_tutorial.md	Updates Alif tutorial for Zephyr 4.4, Python 3.12+, new model naming, and expanded flashing guidance.
backends/arm/test/test_github_trunk_zephyr.sh	Adds --zephyr-dev-root and reuses a single setup across README runs.
backends/arm/scripts/toolchain_utils.sh	Updates Zephyr toolchain download URLs/checksums to SDK v1.0.1 assets.
.gitignore	Ignores the new zephyr_dev_root/ workspace and its backups.
.github/workflows/trunk.yml	Ensures Zephyr CI runs under Python 3.12 by creating/activating a dedicated conda env.
.claude/skills/zephyr/SKILL.md	Updates internal Zephyr skill doc to Zephyr 4.4 / west sdk install / west packages.
.ci/scripts/zephyr_sdk_release_proxy.py	Adds a local synthetic GitHub Releases API/proxy for Zephyr SDK assets with caching + checksum verification.
.ci/scripts/test_zephyr.sh	Refactors Zephyr setup to a configurable workspace, adds setup-only/skip-setup, and SDK proxy fallback.
.ci/docker/common/install_zephyr.sh	Removes pre-downloading Zephyr SDK from the image build step.

---

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[zingo]

@psiddh & @rascani this probably need a Meta review.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 2 comments.

[rascani]

It looks like there are a few zephyr jobs failing, can you take a look @zingo?

Also, I'd like to get a better understanding for the rationale behind the SDK caching/proxying. In general, I'd like to minimize downloads in CI (causes flakes), but to me the ideal is caching most downloads in the docker image.

[rascani]

I don't understand why this was removed? Seems like it would be best to have the download happen during the docker build (so we don't have to redo it on every CI job).

[zingo]

I was planning this for a later PR due to a few reasons:

• I don't think it worked, it worked in our (Arm) internal CI but on github when I checked it didn't pick it up, maybe it was fixed later. I didn't check now.
• The download/install of the new SDK artifacts works different now, Zephyr has it's own install process that is used.
• Keep the patch smaller

But as I already had to handle the rate limiting with a proxy I kind of prepared for this and now when you asked why not... I have now updated with a docker pre-download lets see it if work.

[zingo]

It looks like there are a few zephyr jobs failing, can you take a look @zingo?

Yes seem to be Conda related. Zephyr setup code wants venv, PR updated

Also, I'd like to get a better understanding for the rationale behind the SDK caching/proxying. In general, I'd like to minimize downloads in CI (causes flakes), but to me the ideal is caching most downloads in the docker image.

The SDK download is not a wget thing anymore, it uses zephyr own SDK download and the proxy is a way to trick it for a few reasons like github rate limeting problems, and a way to prepoulate this with the SDK in the docker image (was planning this for a follow up PR but added it to this. Also we are not downloading the full SDK anymore only common+Arm tools so even i cache/proxy is not used the download time went from 5min->40s. We can add cached versions for other target later on when needed in CI like ESP32/RiskV/Cortex-A but I started with small as possible.

[Copilot]

Pull request overview

Copilot reviewed 17 out of 18 changed files in this pull request and generated 4 comments.

[zingo]

Seem to run into this problem #20092