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native preview: CPU baseline check for images above the platform baseline (x86-64-v3, armv8.1-a) - #489
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…line (x86-64-v3, armv8.1-a) The shipped wheels are built with -march=compatibility and run on every CPU of their platform. A reference image built for GraalVM's default baseline died with "Illegal instruction" on an older CPU. _native/cpu.py checks all eight x86-64-v3 features (was avx2, bmi2, fma), LSE atomics for armv8.1-a on arm64 Linux and AVX2 on Windows, never blocks when the CPU cannot be read, and ARCADEDB_NATIVE_SKIP_CPU_CHECK=1 skips it. Unit tests on fake cpuinfo; README section "CPU requirements". Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
tae898
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October 23, 2026 15:54
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Not needed: the native wheel ships -march=compatibility, and the laptop A/B (native-compat, reportable, A/A clean) puts its cost against x86-64-v3 at no more than about 5% on write and load paths, with queries and vector search unchanged (numbers on ArcadeData#10581). A CPU check only matters for an image above the platform baseline, which we do not ship. |
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Note on the base: the native preview wheel (
arcadedb-embedded-native) is not onmainyet. It lives on thenative-*branches, andnative-inlineis the newest tip, so this PR is based onnative-inline, notmain.What
arcadedb_embedded/_native/cpu.pyis a pure-Python CPU baseline check that runs beforelibarcadedbis loaded. A CPU below the image's baseline gets anArcadeDBErrorthat names the missing features, the baseline, the JVM fallback (arcadedb-embedded) andARCADEDB_NATIVE_SKIP_CPU_CHECK=1, instead ofIllegal instruction.Why, and what the baseline really is
An image that needs more than the CPU has dies with
Illegal instructionand no message. That is what a user sees afterpip installon a Proxmox VM with the default CPU type, on a Celeron/Pentium N/J (J4125, N5105), or on a Raspberry Pi 4 / AWS Graviton1 (no LSE atomics).The shipped wheels do not have this problem:
native-spike/scripts/preview-build.shdefaults toMARCH=compatibility(line 16, passed as-march=$MARCHon line 27) and.github/workflows/native-preview.ymlsetsMARCH: compatibilityfor all four platforms. That is baseline x86-64 and generic armv8-a, and it runs on every CPU in the examples above. GraalVM CE's own default (x86-64-v3 / armv8.1-a) only applies to a reference image built withMARCH=x86-64-v3or a local build with the default. So the check is a guard for those images, and it is a no-op for the published wheels: it must not refuse a Celeron or a Pi 4 on acompatibilitywheel, because that wheel runs there.lib.py::_check_cpualready existed for this case but only knew avx2, bmi2 and fma, only Linux x86-64, and had no tests. This PR replaces it with the full list and covers the other platforms.How it detects
flagsline of/proc/cpuinfo: avx, avx2, bmi1, bmi2, fma, f16c, lzcnt (orabm), movbe (the v3 list of ArcadeData#10624)Featuresline:atomics(LSE), only for anarmv8.1-aimageIsProcessorFeaturePresent(40)(AVX2) via ctypesIf the information cannot be read (no
/proc, empty flags, any exception) it logs at debug and continues.ARCADEDB_NATIVE_SKIP_CPU_CHECK=1skips the check. Nothing is checked for-march=compatibility.Docs
native-wheel/README.mdhas a new "CPU requirements" section (baseline, machines below v3, fallback), andbuild-architecture.mdand thebuild_wheel.pycomment point atcpu.py. The repo keeps no changelog.Tests
bindings/python/tests/test_native_cpu_check.py, 12 tests on fake cpuinfo and feature sets: v3 present (also LZCNT aslzcnt), AVX2 missing (J4125-like), Proxmox default CPU, Pi 4 without atomics, arm64 with atomics,compatibilitynever checks, unreadable CPU does not block, skip env var, Windows AVX2, macOS and unknown machines.PYTHONPATH=src uv run --no-project --with pytest --with jpype1 --with numpy pytest tests/test_native_cpu_check.py --noconftest: 12 passed. The CI legs build and parity-test the wheel on the four platforms.🤖 Generated with Claude Code