mirror of
https://github.com/RetroPortingToolKit/psxrecomp
synced 2026-10-28 02:56:36 -04:00
Matthew Stanley
24c6c56cc0
Matched Ape Escape retail SCPH1001 LLE builds identify0661ce77as the visible boot regression: parent155e269breaches game code, while0661ce77stalls near BIOS frame 375. Revert its four dependent follow-ups too; retain PR #326 readback bounds and PR #328 Vulkan aspect changes. The row-by-row raster dispatcher amplifies an existing malformed DMA list into massive GL work. Keep the broader CPU/DMA arbitration experiment separate for compatibility testing. Document attribution, validation, and the temporarily restored interlace limitation. Validation: full Ape target reaches title/menu and frame 11669 on retail LLE; OpenBIOS control reaches frame 3701. Eight focused tests pass; retained GL readback fixture passes 71 checks at both 1x and 4x after linking local SDL with iconv. Beads: beads-iisy; DMA follow-up: beads-eio.3.122.
85 lines
4.3 KiB
Markdown
85 lines
4.3 KiB
Markdown
# Retail BIOS freeze: PR #327 rollback
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Issue: `beads-iisy`. Investigation and validation: 2026-09-07.
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## Confirmed introduction
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The visible retail SCPH1001 boot regression starts at
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`0661ce7773c3b82ea441ac9c82b0df08b4ea1563`, "Preserve active display field
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during interlaced raster drawing", authored by Alexbeav in
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[PR #327](https://github.com/mstan/psxrecomp/pull/327).
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It reached master through [PR #334](https://github.com/mstan/psxrecomp/pull/334),
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merge `421f58ec8c2a07f2cd608c1afa507404076e9882`.
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Matched historical builds used unchanged runtime sources, the same generated
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Ape Escape and SCPH1001 code, BIOS/disc, game config, and OpenGL 2x settings.
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A minimal CMake wrapper adapted the current game's build declaration to the
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older runtime helper. All runs explicitly set `PSX_BIOS_HLE=0`; logs confirmed
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`bios_backend=LLE`, `bios_boot=LLE (real intro)`, and `image=SCPH-1001`.
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| Runtime revision | Result |
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| --- | --- |
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| `47bda817`, parent of original DMA slicing | Game code; normal close at frame 3979 |
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| `8af48ae9`, PR #277 DMA slicing | Game code; normal close at frame 2959 |
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| `99f775c8`, PR #304 before word-cost change | Game code; normal close at frame 3468 |
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| `bc88c06c`, PR #304 word-cost change | Game code; normal close at frame 3845 |
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| `155e269b`, exact parent of `0661ce77` | Game code; normal close at frame 2192 |
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| `0661ce77`, first PR #327 commit | Severe Sony-screen stall around frames 375-376 |
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| `39ebb06f`, master immediately before #334 | Game code; normal close at frame 2652 |
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| `421f58ec`, merged #334 | Same severe Sony-screen stall around frames 374-376 |
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This rules out naming #277 or #304 as the demonstrated introduction of the
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visible freeze merely because they introduced/refined asynchronous DMA.
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## Mechanism and scope
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`GR_RASTER_ROWS` resubmits a primitive once per permitted scanline, changing
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the backend draw area each time. That multiplies backend submissions and
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flushes in the retail BIOS's interlaced display mode.
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A separate DMA defect makes this especially costly: the CPU can overwrite a
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primitive header before the asynchronous DMA walker consumes it. On master,
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BIOS memcpy at `BFC188D8` clears packet `00138CA8` before DMA node 1023 reads
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its link, sending the walker into a malformed `0 -> 1A0000 -> 0` list. The
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per-row renderer magnifies the resulting bogus primitives into massive GL
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work. The apparent freeze can advance roughly a frame over many seconds;
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headless progress alone misses the user-visible failure.
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The immediate fix rolls back only #327's five dependent commits:
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`0661ce77`, `43909718`, `7c4b0300`, `5aee9c83`, and `6fcfb8ad`.
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PR #326's bounded GL readback and #328's Vulkan aspect-ratio changes remain.
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DMA scheduling, BIOS code, generated code, and launcher settings are unchanged.
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This restores the previous interlaced raster behavior, including its missing
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active-field preservation. A replacement should avoid per-row backend draw
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submission and validate real retail BIOS boot as well as field correctness.
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CPU/DMA arbitration is a separate follow-up, `beads-eio.3.122`; its prototype
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needs Vampire Hunter D/Spot Goes to Hollywood compatibility testing before
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integration. Do not mix that wider timing change into this rollback.
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## Rollback validation
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The full Ape game target (SDL3, launcher compiled in, OpenGL, Vulkan compiled
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in) passes retail intro/disc handoff, visibly reaches the title/menu, and
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closes normally at frame 11669. The same rollback executable also passes the
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OpenBIOS LLE control run and closes normally at frame 3701.
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Use the owned SCPH1001 BIOS and Ape disc with:
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```powershell
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$env:PSX_BIOS_HLE = '0'
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& .\ApeEscapeRecomp.exe --no-launcher --bios <SCPH1001.BIN> --disc <Ape.cue>
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```
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Ensure the game's `game.toml` is staged beside the validation executable.
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Judge actual windowed boot, not just a headless frame threshold.
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Passed: `gl_readback_runner_test`, `psx_cyc_batch_test`,
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`dma_gpu_linked_list_timing_test`, `psx_cycle_event_boundaries_test`,
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`ws_prepass_guard_test`, `gpu_primitive_reject_test`, `gpu_sw_edges_test`,
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and `gpu_vk_upload_alignment_test`.
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The real hidden-GL readback fixture passes `checks=71 failures=0` at both 1x
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and 4x on NVIDIA 616.86. Its stock runner initially failed to link because
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the local MSYS2 SDL static library depends on iconv; rerunning the recorded
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link command with `-liconv` allowed both unmodified fixture runs to pass.
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