ef93a4fa14
Source changes (dormant parity infra, retained from iterate 2.AI/2.AO): - xenia-kernel/exports.rs: nt_create_event manual_reset polarity + related event wiring - xenia-gpu/mmio_region.rs: D1MODE_VBLANK_VLINE_STATUS hardcode parity Also lands the audit-runs/ analysis notes (.md/.txt/.json digests) for the iterate 2.x VSync/0x10e8/0x1004 wedge investigation. Raw trace dumps (.jsonl/.gz/.csv/.stdout) and agent worktrees (.claude/) are gitignored as regenerable local artifacts — see memory + HANDOFF for the running findings. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
76 lines
3.9 KiB
Markdown
76 lines
3.9 KiB
Markdown
# Phase C+21 cold-vs-cold result (2026-05-14)
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## Matched-prefix table (vs C+19/C+20 baseline)
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| chain | C+19 | C+20 | C+21 (jitter-1) | C+21 (jitter-2) | C+21 (jitter-3) | C+21 (fresh c21) |
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|--------------------------------|---------|---------|-----------------|-----------------|-----------------|------------------|
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| canary tid=6 → ours tid=1 main | 104,606 | 104,606 | **104,607** | **104,607** | **104,607** | **104,607** |
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| canary tid=4 → ours tid=11 | 11 | 11 | 11 | 11 | 11 | 11 |
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| canary tid=7 → ours tid=2 | 32 | 32 | 32 | 32 | 32 | 32 |
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| canary tid=12 → ours tid=7 | 3 | 3 | 3 | 3 | 3 | 3 |
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| canary tid=14 → ours tid=9 | 41 | 41 | 41 | 41 | 41 | 41 |
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| canary tid=15 → ours tid=10 | 16 | 16 | 16 | 16 | 16 | 16 |
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Main chain ADVANCED +1 vs C+19/C+20 baseline (104,606 → 104,607).
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The +1 is unmasking the next real downstream divergence; the C+20
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wait.begin jitter event at 104,606 is now transparent.
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CRITICALLY: all 4 canary cold samples now agree at 104,607 —
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reading-error #32 jitter cloud is fully absorbed at the diff layer.
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## Floating-event absorption counts
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| run | floating_create (c/o) | floating_wait (c/o) |
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|--------------------|-----------------------|---------------------|
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| jitter-1 | 0 / 1 (tid=15→10) | 1 / 0 (tid=6→1) |
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| jitter-2 | 0 / 1 | 0 / 0 |
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| jitter-3 | 1 / 0 + 0 / 1 | 3 / 0 (tid=6→1) |
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| fresh c21 | 0 / 1 | 0 / 0 |
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`floating_create` reflects C+18 absorption — observed
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in tid=15→10 (the original D-NEW-3 case, still firing 1 ours-side
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handle.create absorb). `floating_wait` is new in C+21 and varies
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with canary's host-scheduler contention pattern. Sister chains see
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no wait.begin absorption (their waits are per-thread, not shared-
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global — strict matching preserved).
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## Cold-stable invariants
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- **ours cold digest**: bit-stable across 3 runs of `xrs-verify-c19`
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(50M instr, 39290 imports, 0 unimpl). No engine source change.
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- **Phase B image hash**: unchanged (no engine source change).
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- **Schema version**: still `1` (wire format unchanged — C+21 is
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diff-tool-only).
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## Reading-error class #32 — diff-tool counter-measure landed
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Pre-C+21, matched-prefix in canary cold-vs-cold could vary by 1+
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indices across canary samples (jitter-1 contended → matched=104,606
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strict-fail; jitter-2 fast-path → matched=104,607 naturally;
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jitter-3 shifted → matched=104,603 strict-fail). Post-C+21, all
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samples yield matched=104,607 — the metric is now stable across
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canary's contention jitter.
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## Outcome
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C+21 LANDED. Main matched-prefix 104,606 → 104,607 (+1) and
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deterministic across canary cold samples. Reading-error class #32
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mitigated at the diff-tool layer. The next real divergence at
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104,607 is an actual structural difference (canary enters another
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CS while ours leaves one) — handed off to C+22.
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## Next target
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C+22 = the new divergence at tid=6→1 idx=104,607 (canary
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`import.call RtlEnterCriticalSection` vs ours
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`import.call RtlLeaveCriticalSection`). Initial framing: appears to
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be a CS-acquire-vs-release ordering difference in the post-fast-
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path RtlEnterCriticalSection sequence. Investigation will start
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with a static read of canary's vs ours's RtlEnter and RtlLeave
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control flow at this guest PC range.
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Alternative: tackle D-NEW-2 (`KeWaitForSingleObject` `timeout_ns`
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sign/scale asymmetry on tid=12→7 idx=3) — small ε-class encoding
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fix, independent of scheduler determinism. Recommended path
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depends on cost estimate; the C+22 framing scope can pick either.
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