ad9c8e4cb8
Sylpheed's title loop re-runs its per-frame manager update sub_821741C8
only when "clock B" ([controller+88], the swap count) changes. Clock B's
sole source is the CP swap-complete callback sub_824CE2B8, which bumps
[gfx+15160] via the TWO-LEVEL deref [[VdGlobalDevice]+0]+15160, where
VdGlobalDevice is the kernel variable export 0x01BE at guest .data
0x82000750.
Ours patched that import slot with literal 0 (the old "passed through to
Vd* shims, write 0" behaviour). Consequences, both confirmed at runtime:
* the guest's graphics init stores its D3D device object via
`stw r31, 0([0x82000750])` (sub_824C6DC0 @0x824C6F18) — with the slot
0, that store lands at address 0;
* the swap callback reads [[0x82000750]] = [0] = 0 and increments
[0+15160] (the null page) instead of the real device's swap counter.
So [gfx+15160] never moved, clock B stayed frozen at 0, sub_821741C8
fired exactly once, and the game submitted one render batch (the 78-draw
splash) then stalled.
Fix mirrors xenia-canary RegisterVideoExports (xboxkrnl_video.cc:557-564)
exactly: allocate a 4-byte cell, point the import slot at it, zero the
cell. The guest then stores its device into the cell, and the callback's
two-level deref resolves correctly. Verified: [0x82000750] now holds a
real cell whose [+0] is the device (gfx state), the swap callback bumps
[gfx+15160] 0->1, clock B advances, and the per-frame chain steps forward
(sub_821741C8 fires 1->2x, GamePart update sub_821C7CB8 0->1x).
Determinism: --gpu-inline digest re-baselined and byte-identical across
runs. The fix shifts the early execution trajectory (clock B unfreezing),
so the n50m golden moves imports 451500->178937 and instructions
50000001->50000014; draws/swaps/RTs/shaders unchanged (78/4/2/3). n2m
golden unchanged (early boot, pre-fix-effect). 675 workspace tests green;
sylpheed_n50m oracle green.
Note: this breaks the FIRST hard blocker (clock B could never advance at
all). Full per-frame sustain (draws past 78) needs a further step: each
GamePart update must submit a per-frame command buffer (with PM4_INTERRUPT)
during the asset-streaming phase to keep generating CP interrupts; ours
currently produces only the single seed interrupt from the initial batch,
so the chain advances once and re-stalls. Tracked for the next iterate.
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.