8b290d7012
Two findings, the second only visible because of the first.
1. The harness has always had kernel logging switched off. log_mask DISABLES
categories (Kernel=1, Apu=2, Cpu=4, Gpu=8), so the long-standing --log_mask=13
meant Kernel+Cpu+Gpu off; kernel calls also log at Debug while log_level
defaults to Info. Seeing one needs BOTH LOG_MASK=12 and LOG_LEVEL=3, and no
boot log this project has taken ever contained a kernel call. boot_menu.sh now
takes LOG_MASK / LOG_LEVEL / EXTRA_FLAGS. A whole boot at Debug with Kernel on
is 23 MB, so the default was costing far more than it saved.
2. With that on, a captured failure shows the (A) handler doing everything right:
XamUserGetXUID(0, 7, ...)
NtCreateEvent(...)
ExCreateThread(..., entry=821748F0, ..., 00000001)
ExCreateThread Active: Thread Initially Suspended,
XThreadF80000CC (1F) Stack: 70880000-70900000
NtResumeThread(F80000CC, ...)
and the thread then never executing. Measured two independent ways: it makes
ZERO kernel calls - it appears 13 times in the log and every one is as an
ARGUMENT, never as the calling thread, while five other threads make 31905
calls after the resume - and its host thread has 00:00:00 CPU time while the
process sits at 546% and has burned 37 minutes of CPU in 6:46 wall.
A spinning thread burns CPU. This one has not run at all.
So the chain is: press delivered -> handler runs -> thread created suspended ->
resumed -> never scheduled. Input, the cache-flush crash and the game's own logic
are all excluded. A lost resume is a race, which is the first explanation that
fits the ~1-in-3 success rate.
Not settled: where the resume is lost, and no successful boot has been captured
with kernel logging to compare against.
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.