fix: keep CPU builds portable across x86 hosts

[efegokdemir]

Summary

• Disable ggml native-architecture optimization by default for CPU presets so release/source CPU artifacts do not inherit AVX-512 instructions from the build host.
• Preserve an explicit -DGGML_NATIVE=ON override for target-specific builds.
• Document the portability contract for CPU presets.

Fixes #23

Validation

• scripts/configure.sh cpu-asr -DNEMO_SPEECH_BUILD_TESTS=ON — passed; generated cache reports GGML_NATIVE=OFF
• Explicit -DGGML_NATIVE=ON override — passed; cache reports GGML_NATIVE=ON
• cmake --build --preset cpu-asr --parallel — passed
• ctest --test-dir build/cpu-asr --output-on-failure --timeout 600 — 10/10 passed
• uvx --from pre-commit pre-commit run --files scripts/configure.sh docs/build.md — passed
• bash -n scripts/configure.sh — passed
• git diff --check — passed

The commit is DCO signed and SSH signed.

Summary by CodeRabbit

• Build Configuration
  • CPU presets on x86_64 and amd64 default native-architecture optimization to off. You can explicitly set GGML_NATIVE to ON or OFF. CPU presets on other architectures and non-CPU presets retain their existing defaults and options.
• Documentation
  • Build instructions explain the x86_64 default and how to set GGML_NATIVE explicitly.

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📝 Walkthrough

Walkthrough

For CPU presets on x86_64 and amd64, the configure script defaults GGML_NATIVE to OFF and accepts recognized boolean overrides. Other presets retain their previous CMake invocation. The build guide documents these defaults and overrides.

Changes

CPU Native Optimization Defaults

Layer / File(s)	Summary
CPU preset option and documentation scripts/configure.sh, docs/build.md	CPU presets on x86_64 and amd64 pass an explicitly resolved GGML_NATIVE value to CMake. The default is OFF, and recognized boolean overrides are accepted. Other presets retain the previous invocation. The build guide documents these defaults and overrides.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: 🟡 Moderate · up to aa4e6

Default CPU artifacts still require AVX2-class instructions, so older x86_64 systems may fail during decoding. Clarify the supported CPU baseline or make the default portable to the documented x86_64 target before merging.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: improving CPU build portability across x86 hosts by disabling host-specific native optimizations by default.
Linked Issues check	✅ Passed	Issue #23 requires the CPU artifact to avoid host-specific instruction requirements or to use clear target labeling. For cpu-* presets on x86_64 and amd64, scripts/configure.sh now defaults `G…
Out of Scope Changes check	✅ Passed	The changes stay within issue #23. scripts/configure.sh changes CPU build defaults, and docs/build.md documents the resulting portability contract. The reported tests validate the changed configur…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…

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Inline comments:
Review comments at @scripts/configure.sh:
- Around line 179-185: Update the `cpu-*` branch in the `PRESET` case in
`scripts/configure.sh` to disable the ggml host-specific ISA options (SSE4.2,
AVX, AVX2, BMI2, FMA, and F16C) for the portable CPU default, and pass those
overrides to the final `cmake --preset` invocation. Leave non-CPU presets and
user override handling unchanged.

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[efegokdemir]

Addressed the CPU portability finding in 28dc604. CPU presets now disable ggml SSE4.2, AVX, AVX2, BMI2, FMA, and F16C options by default in addition to GGML_NATIVE=OFF; explicit user -D overrides remain honored.

Validation: bash -n scripts/configure.sh, git diff --check, a fake-CMake argument test covering default OFF values and explicit GGML_AVX2=ON/GGML_NATIVE=ON overrides, and uvx --from pre-commit pre-commit run --files scripts/configure.sh docs/build.md all passed.

[efegokdemir]

Addressed in 9a6913c. The automatic GGML_NATIVE=OFF default is now limited to x86_64/amd64 CPU hosts; other architectures keep their normal defaults while explicit -DGGML_NATIVE values remain pass-through. The empty-array portability concern is avoided. Validation: bash -n scripts/configure.sh and uvx --from pre-commit pre-commit run --files scripts/configure.sh docs/build.md passed; git diff --check passed. NVIDIA runner vetting remains external.

[efegokdemir]

Updated the branch in aa4e65a to resolve the current merge conflict against upstream main. Preserved the x86 CPU GGML_NATIVE=OFF behavior while adopting upstream's current submodule/patch layout. Validation: bash -n scripts/configure.sh and git diff --check passed; NVIDIA runner validation remains external.