66bd805726
Ours' `vd_swap` wrote its 64-dword XE_SWAP block at the guest's reserved `buffer_ptr` slot AND then bumped the primary ring `CP_RB_WPTR` out-of-band via `state.gpu.extend_write_ptr_by(64)`. That bump was a bug: `buffer_ptr` (~0x4add6efc) is NOT inside the primary ring (base ~0x4adcd000, 8192 dwords) — it lives ~10k dwords past it, in the renderer indirect-buffer region. The bogus WPTR bump pushed the GPU read-pointer PAST the guest's real write-pointer; the drain treated the overshoot as a circular wrap and re-executed the splash's draw indirect-buffers ~2×, inflating draws to 78 (the real splash geometry is ~28 draws; 12 INDIRECT_BUFFERs vs the real 6). Canary's `VdSwap_entry` (xenia-canary xboxkrnl_video.cc:518-548) writes the fetch-constant patch + PM4_XE_SWAP + NOP pad into the reserved slot and returns — it NEVER touches CP_RB_WPTR. The guest advances the primary ring write-pointer itself via its own doorbell once it has populated the slot; swap-complete CP interrupts come only from the game's in-stream PM4_INTERRUPT packets, never from VdSwap. This fix removes only the out-of-band `extend_write_ptr_by(64)` call, keeping the buffer_ptr block write intact and byte-faithful to canary. Effect at `--gpu-inline -n 50M`: draws 78→28, INDIRECT_BUFFER 12→6 (re-execution artifact gone), swaps 4→2. The run now halts at ~19.27M instructions (worker threads exit) instead of spinning to 50M, because removing the corruption unmasks the real per-present-interrupt deadlock — the title loop needs a per-present PM4_INTERRUPT that the stalled game never submits. That deadlock is a SEPARATE, known gate tracked/addressed elsewhere; it is intentionally NOT papered over here. Re-baselined golden crates/xenia-app/tests/golden/sylpheed_n50m.json to the new honest values (regenerated twice, byte-identical). sylpheed_n2m.json is unaffected (draws=0 at 2M). cargo test --workspace: 675 passed. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Sylpheed regression goldens
These JSON files anchor xenia-rs check digest output for Project Sylpheed.
Files
| File | -n | Mode | Captures |
|---|---|---|---|
sylpheed_n2m.json |
2_000_000 | full digest | early boot (swaps=0, no rendering) |
sylpheed_n50m.json |
50_000_000 | stable-digest | first VdSwap pair (swaps=2 post-Phase-A) |
Stable-digest mode
sylpheed_n50m.json is captured with --stable-digest, which omits
timing-sensitive counters: packets (±2–8% lockstep noise from a GPU thread
race), resolves, interrupts_delivered, interrupts_dropped,
texture_decodes. The remaining fields are byte-identical across repeated
lockstep runs at a fixed -n.
sylpheed_n2m.json predates the stable-digest flag and uses full-digest
compare. It still works because at -n 2M the GPU pipeline has not produced any
packets yet — packets=0 is trivially deterministic.
Circularity hazard
Per ORACBUG-001/002/003, these goldens were captured by running the same code
they validate. They detect regression from a known-good snapshot, not
correctness. When a planned fix intentionally moves the digest (e.g. a
shader fix landing draws > 0 for the first time), re-baseline the golden as
a separate commit and reference the audit ID in the message.
Re-baselining
cargo build --release -p xenia-app
target/release/xenia-rs check \
"$SYLPHEED_ISO" \
-n 50000000 \
--stable-digest \
--out crates/xenia-app/tests/golden/sylpheed_n50m.json
Running the goldens
cargo test --release -p xenia-app --test sylpheed_oracles -- --ignored --nocapture
The tests are #[ignore]-gated because each run takes a few seconds, which is
unacceptable in the default cargo test cycle. The ISO path defaults to the
contributor's local ~/RE Project Sylpheed/Project Sylpheed*.iso and can be
overridden via SYLPHEED_ISO=/path/to/sylpheed.iso.
n4b canonical-invocation regression anchor (deferred)
The audit's recommended next sprint also called for a sylpheed_n4b.json
golden capturing the canonical reference invocation
xenia-rs check sylpheed.iso -n 4_000_000_000 --parallel --reservations-table.
This is deferred because:
- The
--parallel --reservations-tablecombination is empirically pathologically slow at -n 100M (>32 min per run per the audit memory). At -n 4B the run cost is many hours, not the single-session-friendly 5–15 min the original plan estimated. - Each phase that intentionally moves rendering counters (C, D, E, F) would need a re-baseline of n4b — a significant time cost compounding over the sprint.
Once the renderer-unblock phases (C+D+E) land and draws > 0 is confirmed at
-n 100M lockstep, an n4b artifact may be captured one-shot and stored under
audit-runs/post-fix/ (not as a test golden) as a manual regression anchor for
the canonical invocation.