handoff: VSync/event-wedge fixes + iterate 2.A–2.BC research notes
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>
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MechaCat02
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audit-runs/audit-059-gamma-wedge/canary-summary.md
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audit-runs/audit-059-gamma-wedge/canary-summary.md
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# AUDIT-059 PROBE C — canary γ-wedge signaler triangulation
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Date: 2026-05-11
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Mode: READ-ONLY canary instrumentation (patch reverted clean).
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Canary HEAD before/after: `6de80dffe` (clean tree confirmed).
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Patch: audit-030 `--log_lr_on_pc` (30 LOC across 4 files; saved to `canary-patches-applied.diff`).
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Build: `cd build && ninja -f build-Debug.ninja xenia_canary` → copied to `xenia-canary-probe`.
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## Phase 1 — handle creation at `sub_821CB030+0x128` (PC `0x821CB15C`)
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Probe target: PC `0x821CB15C` (post-bl after `bl 0x824A9F18` NtCreateEvent wrapper).
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At this PC, `r3` = freshly-created event handle.
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**2 fires captured in 130 seconds** (`canary-ntcreate.log`):
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| # | Wallclock pos | tid (canary) | r3 (handle) | r31 (stack) |
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|---|---------------|--------------|-------------|-------------|
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| 1 | line 2058 | F8000090 | **0xF8000098** | 0x7064FA70 |
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| 2 | line 10567 | F80000CC | **0xF8000108** | 0x708FF990 |
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Both fires precede a **synchronous file-IO sequence** (RtlInitAnsiString → NtQueryFullAttributesFile → NtCreateFile for `cache:\aab216c3\5\...` paths).
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Both events are then `NtDuplicateObject`'d (the duplicate is the real wait target):
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| Original handle | Dup target | Wait-site |
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|-----------------|------------|-----------|
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| `F8000098` (XObject) | `F80000A0` (XEvent) | tid F8000090, NtClose@line 2081 (fast) |
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| `F8000108` (XObject) | `F8000110` (XEvent) | tid F80000CC, NtClose@line 10605 |
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## Phase 1b — wait-site at `sub_821CB030+0x1AC` (PC `0x821CB1DC`)
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Verifies the wait fires in canary too. 2 fires, both with `lr=0x821CB1D0`:
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```
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i> F8000090 TRACE-PC-LR pc=821CB1DC lr=821CB1D0 r3=F8000098 r4=FFFFFFFF r5=BC65CDC0
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i> F80000C8 TRACE-PC-LR pc=821CB1DC lr=821CB1D0 r3=F8000108 r4=FFFFFFFF r5=BC667CC0
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```
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`r4=FFFFFFFF` → INFINITE wait timeout. Wait DOES execute in canary — but completes
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(matched by subsequent NtClose). This is the AUDIT-041 wait-site `bl 0x824AA330`.
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## Phase 2 — NtSetEvent triangulation
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Probe target: NtSetEvent thunk PC `0x8284DF5C` (53,701 fires in 130s).
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Cross-checked against the `sub_824AA2F0` (NtSetEvent wrapper) entry probe (20,919 fires).
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### Identification of wedge-equivalent handle by NtSetEvent fire pattern
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Hypothesis: the dup-XEvent (target of NtDuplicateObject) is what gets signaled.
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In `canary-ntsetevent.log`, **dup handle `F8000110`** appears in NtSetEvent exactly **2×**:
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```
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i> F8000054 TRACE-PC-LR pc=8284DF5C lr=824AA304 r3=F8000110 r5=BC32CC60 r31=7036FDC0
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i> F8000084 TRACE-PC-LR pc=8284DF5C lr=824AA304 r3=F8000110 r5=00000002 r31=705AF860
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```
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`lr=824AA304` = wrapper-internal post-bl PC inside `sub_824AA2F0` (NtSetEvent wrapper).
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To get the **caller LR** (i.e. who called the wrapper), probe the wrapper entry `0x824AA2F0`.
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### Wrapper-entry probe — cross-run structural correlation
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In the wrapper-entry run, the handle namespace shifted slightly (per-run slab-allocator
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nondeterminism), but the **r31 stack invariant** matches across runs.
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Two-fire handle in the wrapper-entry run that matches r31 stack frames `7036FDC0` and
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`705AF860` exactly:
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```
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i> F8000054 TRACE-PC-LR pc=824AA2F0 lr=82458D14 r3=F8000118 r4=BC369420 r5=BC32CC60 r31=7036FDC0
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i> F8000084 TRACE-PC-LR pc=824AA2F0 lr=8245ED80 r3=F8000118 r4=705AF8B0 r5=00000002 r31=705AF860
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```
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**Cross-run match by (tid, r31)**: `F8000054@7036FDC0` and `F8000084@705AF860` are the same
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two threads/stack-frames signaling the cache-IO completion event in both runs.
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### Resolved canary signalers
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| LR | Caller function | Pre-bl insn | Demangled |
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|----|-----------------|-------------|-----------|
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| `0x82458D14` | **`sub_82458B90`** | `bl 0x824AA2F0` @ 0x82458D10 | NtSetEvent wrapper call |
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| `0x8245ED80` | **`sub_8245EC10`** | `bl 0x824AA2F0` @ 0x8245ED7C | NtSetEvent wrapper call |
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Both LRs are NtSetEvent-wrapper call sites. Each fires once per wedge instance.
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## Cross-reference with ours-side (sibling PROBE O findings)
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From `ours-summary.md` (Phase 3 candidate-signaler table):
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| Producer | Fires in ours | Distinct LRs | Notes |
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|----------|---------------|--------------|-------|
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| `sub_82458B90` | **1** | 0x82457f18 (sub_82457EF0+0x24) | direct NtSetEvent caller; **fires once but NOT on wedge handle** |
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| `sub_8245EC10` | **0** | — | **0 static callers** — indirect-dispatch-only (audit-050 dead) |
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### Static caller chains in ours's database
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```
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sub_82458B90 callers:
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└─ sub_82457EF0+0x24 (only caller; sub_82457EF0 itself has 0 static callers — fnptr-array only)
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sub_8245EC10 callers:
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└─ NONE STATICALLY
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Located in dispatch_table @ 0x820B5830 [slot 1]
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slot 0: sub_8245F1D0
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slot 1: sub_8245EC10
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Table referenced from:
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- sub_8245F1D0+0x1C (self-ref recursive)
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- sub_8245FEB8+0x100 (stw r11, 0(r31) at 0x8245FFC0 — class vptr install)
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sub_8245FEB8 callers: sub_8245FB68 (2 sites), sub_824601A0 (1 site)
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sub_8245FB68 callers: sub_8245F880, sub_8245FAB0
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sub_824601A0 callers: sub_82460118
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```
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Both signaler functions live in the worker cluster `0x82458xxx-0x8245Exxx`. `sub_8245EC10` is
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a slot-1 entry in a 2-slot dispatch_table at `0x820B5830` — installed at struct offset 0
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(vptr) by `sub_8245FEB8`'s constructor. `sub_82458B90`'s only static caller chain goes up
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through `sub_82457EF0`, which itself has 0 static callers.
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## Findings
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1. **Wedge structural identification**: `sub_821CB030+0x128` creates a per-call file-IO
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completion XEvent that is immediately duplicated and submitted to a worker
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(`sub_82452DC0` @ +0x19C) for asynchronous file load. The wait at +0x1AC blocks until
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the worker signals the duplicate XEvent.
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2. **Canary signalers (the missing piece)**: Two distinct call-sites signal the wedge
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in canary:
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- `sub_82458B90` (= LR `0x82458D14`)
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- `sub_8245EC10` (= LR `0x8245ED80`)
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Both wrap `bl 0x824AA2F0` (NtSetEvent wrapper). Each fires once per file-IO completion.
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3. **Static-graph triangulation for ours**:
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- `sub_82458B90` has 1 static caller (`sub_82457EF0+0x24`); chain dies because
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`sub_82457EF0` has 0 static callers (fnptr-array activation).
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- `sub_8245EC10` has 0 static callers — vtable slot 1 in dispatch_table `0x820B5830`,
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installed by `sub_8245FEB8` ctor; ctor's reachability chain also dies in the
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`0x82458xxx-0x8245Fxxx` cluster.
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4. **The wedge is downstream of AUDIT-050's unreachability island**. Both canary
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signalers live in the half-bootstrapped worker cluster. The work-submitter
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(`sub_82452DC0`) DOES fire in ours (8× per PROBE O) on tid=13 — but the queued
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work never reaches a worker that calls `sub_82458B90` or `sub_8245EC10` because
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the worker-side dispatch infrastructure (vtable install via `sub_8245FEB8` ctor;
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fnptr-array activation of `sub_82457EF0`) never runs in ours.
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5. **AUDIT-058's `sub_825070F0` activation hypothesis is corroborated**: `sub_825070F0`
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(AUDIT-057's top missing-thread spawner, 4 workers @ ctx 0xBCE25340) is the
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plausible bootstrap for the workers that would receive the queued work and run
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the dispatch_table @ `0x820B5830` callbacks. Until that spawn happens in ours,
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the worker side stays dead → signal never lands.
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## Recommended AUDIT-060
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1. **Direct path**: probe `sub_82452DC0+0x19C bl` site in canary (with our existing
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`--log_lr_on_pc=0x82452E5C` or post-bl PC) to trace what happens after work submission.
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Find which worker thread (one of the 4 spawned by `sub_825070F0`) dequeues the job
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and ultimately calls `sub_82458B90` or `sub_8245EC10`.
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2. **Indirect path**: probe `sub_8245FEB8` (vptr installer for dispatch_table `0x820B5830`)
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in canary AND ours. If it fires in canary but not ours, that confirms the worker-class
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constructor is in the unreachability island.
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3. **Bootstrap path**: trace what activates `sub_825070F0` in canary (per AUDIT-058 it
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fires 1× post-`\\dat\\movie` ResolvePath). Capture LR at `sub_825070F0` entry in
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canary, then check that LR's caller-fn for fire count in ours.
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## Artifacts
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```
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xenia-rs/audit-runs/audit-059-gamma-wedge/
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canary-patches-applied.diff (audit-030 patch record before revert)
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canary-ntcreate.log/.err (Phase 1: PC 0x821CB15C, 2 fires)
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canary-waitsite.log/.err (Phase 1b: PC 0x821CB1DC, 2 fires)
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canary-ntsetevent.log/.err (NtSetEvent thunk PC 0x8284DF5C; 53,701 fires; r3=F8000110 ×2)
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canary-setwrapper.log/.err (NtSetEvent wrapper PC 0x824AA2F0; 20,919 fires; r3=F8000118 ×2)
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canary-summary.md (this file)
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ours-summary.md (sibling PROBE O ours-side findings)
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```
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Canary HEAD verified `6de80dffe`, working tree clean. xenia-rs untouched.
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