fp-hw-survey capture: Ampere Altra / AWS Graviton (arm64/Linux)

[MikeGrier]

Capture native FP behavior on a server ARM64 part — Ampere Altra and/or AWS Graviton2/3/4 (aarch64 / Linux) — with crates/fp-hw-survey.

Steps

cargo build --release -p fp-hw-survey
./target/release/fp-hw-survey info        # confirm CPU brand + features (rpres/afp probed via std runtime detector on Linux)
./target/release/fp-hw-survey selftest    # must pass
./target/release/fp-hw-survey capture --label <ampere-altra|graviton3>-linux

What to attach to this issue

• The info output (CPU brand + detected features).
• The selftest result (must be clean — capture refuses to write otherwise).
• The one-line NDJSON header from the capture (durable provenance: cpu / os / features / date).
• The capture-*.ndjson file itself (attachment or link).

Notes

• On Linux the std is_aarch64_feature_detected! path is active, so rpres/afp are detected where present — these are the only knobs that can change a single-precision estimate value.
• Microsoft Cobalt 100 (Neoverse-derived) is explicitly out of scope for now per rook DESIGN-NOTES D-37; do not file it under this issue.

Part of the FP hardware survey fleet-capture campaign.