09f189bf12
Built upstream/canary_experimental (a5a18f5c7, 82 commits ahead of our merge base) clean, to answer whether the 0x82307128 mission crash is ours or theirs. Two tooling gaps found building it: version.h is never generated (upstream's xenia-build.py writes it, build-canary does not invoke it, and our tree only builds because a stale copy from an old sylpheed-re build sits in the build dir), and build-canary reports exit 0 on a FAILED build - only the missing binary gave it away. Pure upstream cannot be driven at all: --hid=file is ours and there is no uinput here. So the honest baseline is upstream plus those three pad commits. That baseline reproduced the LOST RESUME on its second boot - black screen, guest at 522% CPU, newest host thread at 00:00:00 CPU, zero kernel calls from its handle - and upstream's threading_posix.cc still has the two-lock-scope publish. So pure upstream is not a stable state; it carries a bug we had already fixed. Adding ONLY the threading fix on top - still none of the RE instrumentation - reaches Stage 02 FLIGHT: TIME 05:03.75, wingman Rhino 103, radio dialogue, and REMAINING OB 020 with OB badges on targets. The run ended in a legitimate GAME OVER (the unattended craft was shot down, as autopilot-memory-driven.md warns), not a crash. Crash dumps for the whole run: 0, against 384 on the instrumented branch at the briefing alone. So the mission crash is not upstream's. Whether it is in our 50 commits or fixed among upstream's 82 this run does not separate; that needs a bisect. REMAINING OB is visible and moves (020->019->018->017) but is NOT found. A three-snapshot BE-u32 filter left 0 survivors; a differential across widths gave exactly one candidate, 0xbc22e83c, and it is REFUTED - read live it held 26 while the HUD showed 017. The empty u32 filter is itself informative: the counter is not a plain persistent big-endian word.
Reverse-engineering knowledge base
This directory is the spec-side of the clean-room: it records what the original Project Sylpheed binary does (behaviour) and how its data is laid out, so that the Rust port can be implemented from these specs without re-deriving anything and without ever copying original code.
It exists to answer one question fast: "do we already know how X works, and how sure are we?"
The one rule that matters
Never document a claim more confidently than the evidence supports, and never paste original code here.
A wrong-but-confident note is worse than no note: someone builds on it and the bug hides for weeks. Every entry therefore carries an explicit confidence and its evidence. This mirrors the project method — measure the oracle, never infer; refute before believing.
Clean-room firewall
- ✅ Allowed: behaviour descriptions, field offsets/types, formulas, state machines,
observed input→output pairs, and references to the original by address
(
sub_821B68C0) or toxenia-rs/sylpheed.db. - ❌ Forbidden here and in
crates/: pasted decompiled C/C++ or verbatim disassembled function bodies presented as the thing to reimplement. Cite the address; describe the behaviour in your own words. Disassembly is a tool for understanding, not a source to copy.
Confidence levels
| Level | Meaning | Bar to reach it |
|---|---|---|
CONFIRMED |
Behaviour verified against ground truth. | ≥2 independent observations or one observation cross-checked against an oracle (canary framebuffer, a known-correct value, a second code path). |
PROBABLE |
Strong single-source inference. | One clean observation, or an unambiguous static read of the disassembly. |
HYPOTHESIS |
Educated guess, not yet tested. | Anything else. Must say what would confirm/refute it. |
Promotion requires new evidence, not re-reading the old evidence. A HYPOTHESIS that
"looks right again" is still a HYPOTHESIS. Only an independent check promotes it.
If evidence later contradicts an entry, demote it and record the contradiction — do
not silently edit the conclusion.
When to document
- Right after a function/structure crosses from
HYPOTHESISto at leastPROBABLE— before moving to the next code path, so the knowledge isn't lost or re-derived. - Whenever confidence changes (up or down) — append to the Evidence log, don't overwrite.
- Not while it's still a pure guess with no evidence — a one-liner in the relevant backlog/plan is enough until there's something to stand on.
What to document
- Functions/code paths →
docs/re/functions/<name>.md(one file per function or tight cluster). - Data structures / formats →
docs/re/structures/<name>.md. - Keep the index in
INDEX.md(one line each: name · confidence · one-line summary).
Use the templates: _TEMPLATE.function.md,
_TEMPLATE.structure.md.
How we find and confirm code paths (the toolchain)
Everything joins on the guest virtual address (PC) — code addresses are fixed by the XEX load, identical across our emulator and canary.
- Static (cheap, try first):
xenia-rs/sylpheed.db(DuckDB: 25 481 functions, xrefs, strings, vtables, imports). Query withxenia-rs/zq.py—zq.py grep <str>,zq.py xref <addr>,zq.py dis <lo> <hi>,zq.py fn <pc>. Entry points are usually a string (zq.py grep MSG_DEMO) or an import (movie/XMA API) xref'd back to the loader. - Dynamic (when static is ambiguous): run
xenia-rswith its probe suite —--pc-probe/--audit-pc-probe-hex(fires at block entry),--mem-watch(mid-block reads/writes of a VA),--lr-trace(call/return chains),--trace-instructions,--dump-addr(read guest memory). These already exist; prefer them over hacking canary. - Oracle (correctness ground truth): canary — the Wine cross-build
xenia-canary/build-cross/bin/Windows/Debug/xenia_canary.exe(the native Linux ELF crashes / does not run — do not use it). This is the only emulator that reaches the in-game menu; ourxenia-rsnever got past the intro video. Use canary to observe output (capture its framebuffer for texture colours), not usually to instrument code — though itsbuild-crosstoolchain does compile, so small C++ probes + rebuild are possible when needed. Run muted, one emulator process at a time, point it at the real ISO (not the symlink).
⚠️ VA-equality caveat: join code by PC (fixed), but never assume a data VA holds the same bytes across emulators — allocators differ. Compare data by content/layout.