Shokunin 1c56a8b78c segment_testrom: line-align the probe call sites so the T2 deltas compare ...

With the delay-slot fix the Beetle deltas were sane but not comparable: the
three unrolled call sequences sat at different I-cache line offsets, and
probe_run shared a line with seeded, so the KUSEG run found its first line
already filled. Beetle read 59/59/89 (KUSEG/KSEG0/KSEG1), where the fetch
model predicts a 23-cycle KSEG1 surcharge.

Pad each call sequence so its first T2 read starts a line, and start
probe_run on its own line. Beetle (disc boot, OpenBIOS and SCPH-1001 alike)
now reads 56/56/82: KUSEG equals KSEG0, and KSEG1 exceeds them by 26 cycles,
exactly the Beetle fetch-model difference for the 15 KSEG1 fetches (60 vs a
cold cached 34).

probe_run moves to 0x000100F0. Ledger ids are unchanged; fetch-tag-segment
counts 30 tags and alias-fetch-coherence reads 22 vs Beetle 11, because leaf
now straddles two lines.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-09-29 18:20:52 -07:00

..

gen_segment_exe.py

segment_testrom: line-align the probe call sites so the T2 deltas compare

2026-09-29 18:20:52 -07:00