Diagnostic-only, read-only. Lockstep `instructions=100000002`
preserved bit-exact at -n 100M --stable-digest. 586 → 588 tests.
Adds two read-only diagnostics for the parked-waiter producer hunt:
* `--ctor-probe=0x8217C850,0x...` — at every interpreter step,
if `ctx.pc` is in the configured set, print one `CTOR-PROBE`
line capturing live r3 (= `this` in MSVC PPC ctors), lr
(= return site), sp, plus an 8-frame back-chain with
saved-r31/r30 per frame. Fires once per hit, exactly what the
8-instance-pool probe needed.
* `--dump-addr=0x828F3D08,0x828F4070,0x828F3EC0,...` — at end of
run (after the FOCUS report in `dump_thread_diagnostic`), each
address gets a 128-byte hex + be32 + ASCII dump. Used to
inspect the static dispatcher / job-queue struct layouts
AUDIT-003 identified.
Both gated default-off; empty set is a single `is_empty()` test on
the hot path. No guest state is mutated, so the
`sylpheed_n*m.json` lockstep digest is preserved.
KRNBUG-AUDIT-004 findings (corrects KRNBUG-AUDIT-002/003):
1. **The "8-instance pool" hypothesis for handle 0x1004 is FALSE.**
Probing the inner per-instance ctors `[0x821783D8, 0x82181750,
0x821701C8]` at -n 50M shows each fires EXACTLY ONCE with
r3 = `[0x828F3EC0, 0x828F3D08, 0x828F4070]` respectively. All
three handles are Meyers-style singletons with one dispatcher
each. The "called 8 times" claim came from miscounting raw
entries to the OUTER getter sub_8217C850 — but that getter is
itself a Meyers-singleton-getter; only the FIRST entry cascades
through to bl 0x821783D8 (gated on `[0x828F48D8] bit 0`).
2. **The producer indirection layer is the singleton-getter
itself.** Static byte-scan of .rdata / .data shows 0 hits for
the dispatcher addresses — no static registry table holds them.
But the xrefs table for the OUTER getters reveals 5–6 callers
each, MOSTLY non-create-chain, sharing the canonical producer
pattern: `bl outer_singleton_getter; lwz r3, OFFSET(r3); bl
0x824AA1D8` (with OFFSET=80 for 0x100c, =36 for 0x15e0). So the
AUDIT-003 xref audit was necessary but not sufficient — it
correctly saw "no direct producer references" but missed the
singleton-getter indirection layer.
3. **Dispatcher struct layouts** (128-byte dumps captured at -n
50M --halt-on-deadlock):
- 0x828F3D08 (handle 0x100c): event_handle at +0x4C (0x100c),
thread_handle at +0x48 (0x1010), self-pointer at +0x74,
capacity 7 at +0x28, queue empty (+0/+3C = -1).
- 0x828F4070 (handle 0x15e0): event_handle at +0x20 (0x15e0),
sibling-handle 0x15E4 at +0x1C, queue empty (+0x10 = -1).
- 0x828F3EC0 (handle 0x1004): event_handle at +0x78 (0x1004),
4 guest-heap sub-buffers at +0x20/+0x3C/+0x44/+0x50 in
0x4xxxxxxx range — noticeably different layout from the
other two pure POD job queues.
Files:
crates/xenia-kernel/src/state.rs ctor_probe_pcs / dump_addrs +
fire_ctor_probe_if_match + 2 tests
crates/xenia-app/src/main.rs Exec --ctor-probe / --dump-addr
CLI parsing, prologue hook,
end-of-run struct dumper
audit-findings.md KRNBUG-AUDIT-004 entry
audit-runs/audit-004/ 50M probe runs (v1 outer-getter
hits, v2 inner-ctor hits proving
the singleton hypothesis)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
