D109 - The GPU is probed by executing shaders and reading result bits

Status: decided Date: 2026-09-26

160-gpu dispatches compute kernels over known inputs and records the output bits per lane. Every run emits a gpudev record naming the backend, device and device type, and the checks keep derived provenance because whether a result is silicon is a run-time fact. Device selection takes the first non-CPU device and falls back to a software rasteriser only when nothing else exists.

Why: what an instruction computes is what an emulator's shader translation must match and cannot answer about itself. The same code on a software device and on silicon must never be confused, so the device is the provenance.

Rejected: probing only the graphics API calls - says nothing about instruction results. Taking the first enumerated device - can silently measure a CPU.