The v3.0 Japanese (SCPH-5500, 09/09/96) and US (SCPH-5501, 11/18/96)
retail BIOS images join SCPH-1001, SCPH-101 and SCPH-5552, so every v3.0
region (J, A, E) has a profile.
Both images match SCPH-1001 v2.2 byte for byte in the kernel,
ROM [0x80, 0x18000). SCPH-5501's reset vector is identical too; SCPH-5500's
differs in 24 bytes. The shell differs in both. So each profile is
SCPH1001.toml with its own identity (name, id, rom, sha256 pin, stem): the
copy windows and install slots are kernel properties and carry over
unchanged. The shell runs through the dirty-RAM interpreter, as for
SCPH5552.
Each image gets its own seed list, derived by the same rule as
phase2_ghidra_seeds_SCPH5552.json: the SCPH-1001 corpus filtered to seeds
whose 64-byte ROM window is identical in both images (534 kept, 569
dropped), plus the two architectural vectors and 6 A0/B0/C0 kernel-table
targets. The files carry only addresses, labels and rationales, plus the
SHA-256 of both ROMs.
- psx_bios_known_images.h: CRC-32 FF3EEB8C (SCPH-5500) and 8D8CB7E4
(SCPH-5501), both 512 KiB. A build that does not link these backends
builds one from the player's own dump as a loadable module, like
SCPH-5552, and the netplay lobby can name the image.
- main_cli.cpp: map SCPH5500 / SCPH5501 dumps to their profiles.
- build_cli.py: package both profiles with the CLI framework.
- docs/BIOS_SELECTION.md: list them among the module-built images.
Decision (Alex, 2026-09-30): the recompiled BIOS carries the same risk as
the recompiled game, which titles already commit, so the retail backend is
compiled in rather than built on the player's machine. The retail image is
still never shipped: the runtime needs its data at run time and accepts only
the exact image the backend was built from, so the player supplies their
own dump as before.
- generated/{OpenBIOS,SCPH1001}_{full,dispatch}.c and their .emitter.sha
stamps are tracked (.gitignore un-ignores exactly those); regenerated with
the current emitter.
- bios_emitter_fingerprint.sh no longer hashes the ROM image: the profile's
SHA-256 pin stands for it and the emitter refuses any other image, and CI
has no dump, so hashing it made every CI configure read "stale".
- runtime.cmake: the staleness check covers every LINKED stem and
-DPSXRECOMP_BIOS_STALE_FATAL=ON makes a stale stamp fail configure.
- game-release.yml: no CI-side OpenBIOS emission (generate_openbios.sh is
gone); configure with BIOS_STALE_FATAL and assert both backends linked.
check_generated.sh asserts the submodule carries both backends tracked
and no dump is tracked anywhere.
- The player-side module build stays for a known image a build does not
link (SCPH-5552).
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Bundled releases link OpenBIOS only; retail-BIOS-derived C never ships.
"Bring your own BIOS" now works without it: when a dump matching a shipped
profile (psx_bios_known_images.h) is selected, the runtime builds that
backend on the player's machine with the overlay toolchain the release
already carries, caches it, and loads it as one more registered backend.
- runtime/include/psx_bios_module.h: the module contract. An overlay-style
self-contained shared library (no imports from the executable) exporting
psx_bios_module_{abi,codegen_hash,init,backend}; reaches the runtime only
through OverlayCallbacks plus a new PsxBiosModuleCallbacks table (traps,
dirty-RAM/kernel-bless probes, fntrace, log_probe) and pointer aliases of
the globals the generated dispatcher touches. Its #defines rewrite the
emitter's own extern lines, so the generated C compiles unchanged.
- runtime/include/psx_bios_module_glue.c.inc: module-side forwarders and the
four exports, compiled after overlay_dispatch_preamble.c.inc.
- runtime/src/psx_bios_module.c: host side. Cache path
<exe>/cache/bios/<os-arch>/bm<abi>_<codegen hash>_f<flavor>/<STEM>_<crc>,
ABI + codegen-hash gated load, callback fill, and a blocking build via
overlay_toolchain/bios_module_build.py (gcc via compiler.txt or PATH,
else tcc), then psx_bios_register().
- psx_bios_backend.c: the registry is now a mutable table seeded from the
CMake-generated psx_bios_builtin_registry by a constructor, with
psx_bios_register(); every existing walker keeps working.
- main.cpp: validate_bios_for_launch acquires a module (announcing a first
build) before declaring a mismatch; discovery accepts a buildable dump;
the launcher verify reports it usable ("ready" / "compiled on first
launch") with no Generate & rebuild; the BIOS row shows whenever the
toolchain is present; bundled_only respects module support.
- emitter: the CPS-marker constructor is not emitted in a module build.
- overlay_api.h: OverlayCallbacks gains a struct tag;
overlay_loader_callbacks() exposes the host table before loader init.
- tools/bios_module_build.py (ships in the toolchain): identity + profile
SHA-256 gate, staged emitter tree, emit, three-TU compile, ctypes
self-check, atomic publish. release_stage.py stages psxrecomp-bios, every
bios/*.toml, the seeds and the builder into overlay_toolchain/.
- Tests: runtime/tests/test_bios_module_host.c against three fake modules
(good / wrong ABI / wrong hash) on real dlopen; recompiler/tests/
test_bios_module_build.py builds the bundled OpenBIOS end to end and reads
the descriptor back; guards extended.
Verified on Twisted Metal 4 (bundled build + staged toolchain, headless):
first launch with --bios SCPH1001.BIN builds and loads the module and boots
on image=SCPH-1001; the second launch loads it from cache.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
The lobby's BIOS identity was a two-value token, openbios or scph1001,
and scph1001 meant "some retail dump". An SCPH-5552 peer and an
SCPH-1001 peer both offered it, the host settled it, each peer booted
its own image, and the rollback boot digest never matched: about 20 s
of black window, then both players back in the lobby with no reason
(reported in #243).
Each offer now carries the CRC-32 of the retail image that peer would
boot (online bios_offer.retail_crc; LAN JOIN line 6). The host settles
retail only when every seat offers the same CRC, else OpenBIOS when
every seat links it, else refuses to start and puts the reason on the
launcher's status line ("Players use different BIOS images (SCPH-5552
and SCPH-1001) ..."). The settled CRC ships in match_caps
(session_bios_crc) and on MOTK1 START line 7, and each peer boots only a
dump with that CRC. Rooms where every peer has the same image keep
working, including SCPH-5552-only builds with no OpenBIOS. Old peers
send no CRC, so a mixed old/new room falls back to OpenBIOS or refuses;
a session from an old host still accepts any retail dump. The lobby
server relays bios_offer and match_caps as opaque objects, so it needs
no change.
The rule lives in netplay_bios_settle.c, shared by the online and LAN
paths and covered by netplay_bios_settle_test. last_error grows to fit
one sentence, with psx_lobby_set_last_error to set it.
`bios_hle` (default on) is the player-facing "skip the BIOS and go
straight to the game" flag, and it did nothing under the bundled
OpenBIOS: choosing OpenBIOS sat the player in the boot animation while
the identical build on retail SCPH-1001 went straight to the game.
Root cause was ordering, not policy. The tier has two axes with
different per-image requirements:
* boot-skip needs only `shell_entry_phys`, works under pure LLE
(nothing is synthesized — the shell call just returns
immediately), so any image exporting it can skip
* kernel-call needs `deliver_event_ret`, the kernel's own
DeliverEvent `$ra`, or a delivered callback returns to
the wrong PC
main.cpp correctly refused the call axis on an image without
`deliver_event_ret` by assigning `bios_hle = false` — and then derived
`boot_skip` from that already-mutated flag. OpenBIOS omits
`deliver_event_ret` (B0 semantics unvalidated) but DOES export
`shell_entry_phys`, so an available skip was cancelled by an unrelated
refusal, and one flag meant two things depending on a BIOS detail no
player can see.
Both axes are now decided by one pure, dependency-free function,
`psx_bios_hle_plan()` (runtime/src/bios_hle_plan.c): the boot decision
reads the REQUESTED `bios_hle`, each axis is gated on only the anchor it
needs, and refusals are reported at startup instead of downgrading
silently. `psx_bios_hle_configure()` clamps `boot_skip` to
`shell_entry_phys != 0` as a backstop so the banner and `hle_dump`
cannot overstate what can fire. The main.cpp local is renamed
`bios_hle_requested` and is no longer written back from the plan — the
`session_reboot` path re-enters that block, so folding a refusal into
the request would have made a netplay rematch differ from first launch.
Also in this pass:
* A BIOS profile's `[runtime]` block was parsed into
`BiosConfig::runtime` and read by NOTHING, and bios/OpenBIOS.toml
carried an inert `bios_hle = false` there that read as the reason HLE
was off on OpenBIOS. It was not. `load_bios_config` now REJECTS
`[runtime]` in a BIOS profile: a profile states facts about an image,
never preferences.
* `psx_icache_fastpath_test` had been unbuildable ("redefinition of
`psx_advance_cycles`" — the test's counting stub vs the header's
`static inline`), which blocked every runtime test registered after
it. It now builds with `PSX_OVERLAY_DLL_BUILD=1`, the seam
psx_cycles.h already provides for a TU supplying its own advance.
Tests: new `bios_hle_plan_test` pins the matrix, including a 64-case
sweep asserting the boot decision is independent of
`deliver_event_ret` and the call decision independent of
`shell_entry_phys`. Runtime ctest 15/15, recompiler ctest 30/30.
Validated on Ape Escape (SCUS-94423) built against this framework with
both backends linked, headless, all four cases:
OpenBIOS default bios_boot=skip to game; route=2 fire at vec 0x30000
ra=0xBFC06EA8 (the continuation OpenBIOS.toml
documents); in-game on screen
retail default bios_boot=skip to game; route=2 at vec 0x30000
ra=0xBFC0702C; in-game on screen; differs only in
bios_backend=HLE (LLE fallback)
PSX_BIOS_HLE=0 bios_boot=real intro; ring empty (no hook)
KEEP_INTRO=1 bios_boot=real intro; ring empty
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
These are not stale-by-omission; each asserts something the code does not do,
and each was verified against the implementation before editing.
docs/BUILDING.md
- PSX_ENABLE_VULKAN was documented "off by default" in two places. It
defaults ON (runtime/runtime.cmake:778). Corrected both, and noted that
the build option being ON does not make Vulkan the runtime renderer.
- Removed the PSX_BUILD_COSIM row: no option() for it exists anywhere in
the tree. Replaced with PSX_NETPLAY, which is real (runtime.cmake:194).
- Step 2 (regenerate BIOS) was labelled "(Optional)". It is required before
the first runtime build: step 3 configures psx-runtime from
generated/OpenBIOS_full.c and fails at configure time without it
("Cannot find source file" / "No SOURCES given to target"). Regenerating
the *retail* backend remains genuinely optional; that distinction is now
explicit.
- "This repository has no required git submodules" contradicted .gitmodules
(recomp-ui, lib/recomp-net) and README's --recurse-submodules clone.
Replaced with a table of which submodule each build option needs.
docs/ARCHITECTURE.md
- Same Vulkan default correction.
- Removed the claim that BIOS and game configs merge with "game wins on
scalar keys". No such merge exists: load_bios_config is called only from
the recompiler front-ends (main_bios.cpp, and main_psx.cpp solely to build
the BiosAddressModel) and never from runtime/src/main.cpp.
docs/config_schema.md
- Same merge claim, stated in more detail. Replaced with the actual runtime
precedence: env > CLI > settings.toml > game.toml > compiled default.
docs/STRING_TRANSLATION.md
- Header said "SPEC (design only - no implementation yet)" above a shipped
feature: runtime/src/text_xlate.cpp (~970 lines), initialised from
main.cpp, configured via [localization]. Marked IMPLEMENTED and added the
public entry points.
docs/FEATURES.md
- Layer A (dynamic DLL overlay loading) was headed "SHELVED". It is the live
production dispatch path: overlay_loader.c is ~4,400 lines with 15
LoadLibrary sites, last modified 2026-07-26, and COMPILING_OVERLAYS.md
documents shipping the resulting .dll shards in releases. Added a status
banner and kept the original account as history, since the CRC-keying
dead ends it records are still worth reading.
docs/BIOS_SELECTION.md
- Claimed the identity gate checks "size, CRC32, SHA-256". It checks size
and CRC32 only (bios_backend_for_file, main.cpp:1088-1089); image_sha256
is recorded metadata and never enters the accept/reject decision.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Writes down the contract before implementing it, because one part is a
behaviour change someone would otherwise file as a bug.
The rule: no BIOS chosen -> OpenBIOS; a BIOS the player explicitly chose
-> that BIOS. A developer can require retail for a title with a verified
OpenBIOS incompatibility via [runtime] openbios = false.
"Chosen" means --bios or a launcher/settings pick, and nothing else.
Today resolve_bios_path() also searches directories near the executable,
so a stray SCPH1001.BIN would silently win even though the player never
asked — making behaviour depend on what happens to be on disk. Discovery
stops being a selection mechanism.
Also recorded: why both BIOSes are compiled into one binary (a build
flavour per BIOS needed the same choice restated in three places that
nothing cross-checked, and it compiled cleanly when they disagreed); why
that is affordable (game C is byte-identical across profiles — verified
on Tomba!, Tomba! 2 and Ape Escape — so only the BIOS is duplicated, and
the two collide on just 22 symbols); that the developer setting is not
player-overridable; and that savestates are BIOS-specific and must be
refused across BIOSes, which is the one silent-corruption risk here.
README gets a player-facing version: you probably don't need a BIOS,
here's how to use your own, saves work either way, savestates don't mix.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Alexandros Mandravillis