ef93a4fa14
Source changes (dormant parity infra, retained from iterate 2.AI/2.AO): - xenia-kernel/exports.rs: nt_create_event manual_reset polarity + related event wiring - xenia-gpu/mmio_region.rs: D1MODE_VBLANK_VLINE_STATUS hardcode parity Also lands the audit-runs/ analysis notes (.md/.txt/.json digests) for the iterate 2.x VSync/0x10e8/0x1004 wedge investigation. Raw trace dumps (.jsonl/.gz/.csv/.stdout) and agent worktrees (.claude/) are gitignored as regenerable local artifacts — see memory + HANDOFF for the running findings. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
86 lines
4.0 KiB
Markdown
86 lines
4.0 KiB
Markdown
# Review A Step 1 — `--force-spawn-workers` crowbar spec
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**Date**: 2026-05-27
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**Status**: LANDED; PRIMARY gate FAIL (progression metric unmoved).
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This run re-validates and documents the pre-existing v1/v2/v3 crowbar
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implementation under the canonical "Review A Step 1" framing. The
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implementation already lives in the working tree (committed-like, not
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yet `git add`-ed). This session re-runs the gates and lands the
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default-OFF determinism + PRIMARY-gate verdict on the present HEAD.
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## Implementation surface (already in working tree)
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- `crates/xenia-kernel/src/exports.rs`
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- `CROWBAR_WORKER_ENTRIES = [0x82506528, 0x82506558, 0x82506588, 0x825065B8]`
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- `CROWBAR_VTABLE_BASE = 0x8200_A1E8` (reading-error #37 honoured: this is the vtable BASE, not slot-N)
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- `CROWBAR_STACK_SIZE = 65_536`
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- `crowbar_spawn_one_worker()`: allocates thread image, allocates
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handle, spawns via `state.scheduler.spawn(SpawnParams { ... })` with
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`create_suspended=true, affinity=0, priority=0`, retains self-ref.
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- `crowbar_dump_vtable_region()`: read-only diag dumping 128 vtable
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u32 slots so we see slots 35-38 (offsets 140/144/148/152) used by
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the worker entry stubs.
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- `crowbar_maybe_install_vtable_from_file()`: v2 opt-in via env var
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`XENIA_CROWBAR_VTABLE_BIN`; no-op if unset (this run leaves unset
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because ours already has the vtable populated — see results).
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- `crowbar_maybe_install_ctx_from_file()`: v3 opt-in via env var
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`XENIA_CROWBAR_CTX_BIN`; installs canary-captured 64-byte ctx
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blob (vptr / self / self / refcount / sentinels /
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secondary-obj-ptr / float).
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- `crowbar_force_spawn_workers()`: orchestrator. Allocates a 0x1000
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ctx page, installs `{vptr, self, self, refcount=1}` POD-copy
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head, optionally installs vtable + ctx blobs, spawns 4 workers,
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resumes 4 workers. Returns count resumed.
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- `crates/xenia-kernel/src/state.rs`
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- `KernelState::crowbar_workers_enabled` (bool, default false)
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- `KernelState::crowbar_workers_trigger_instr` (u64, default
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`20_000_000`)
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- `KernelState::crowbar_workers_fired` (bool latch)
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- `KernelState::try_fire_crowbar_workers(&mut self, &GuestMemory,
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instruction_count)`: at-most-once helper; no-op when disabled, when
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already fired, or before threshold.
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- `crates/xenia-app/src/main.rs`
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- `--force-spawn-workers` CLI flag on the `Exec` subcommand
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(line ~278) → sets `XENIA_CROWBAR_WORKERS=1` for downstream wire-up
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(line ~455).
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- Env-var wire-up in `cmd_exec_inner` (~line 1212): reads
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`XENIA_CROWBAR_WORKERS=1` and `XENIA_CROWBAR_TRIGGER_INSTR=N`.
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- **The trigger call** is at `coord_pre_round` (~line 2479) inside
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the per-round prologue, gated on
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`kernel.crowbar_workers_enabled && !kernel.crowbar_workers_fired`.
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- `check` subcommand has NO `--force-spawn-workers` flag; activation
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via env var works for both `exec` and `check`.
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## Crowbar firing-moment choice
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**Option β = fixed cycle threshold of 20M instructions.**
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20M ≈ 3 s wallclock at lockstep cadence, well past:
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- the 10-thread initial spawn burst that peaks around boot-init
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VdSwap, and
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- the AUDIT-049 wedge crystallisation at host_ns ≈ 1.728 s
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(~12-15M instr).
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The trigger fires once and latches `crowbar_workers_fired = true` so
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the helper is at-most-once per process lifetime.
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## Default-off invariant
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- `crowbar_workers_enabled` defaults to `false` in `KernelState::with_gpu()`.
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- The trigger condition `kernel.crowbar_workers_enabled && !kernel.crowbar_workers_fired`
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short-circuits the helper when disabled.
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- Env-var read returns `false` when `XENIA_CROWBAR_WORKERS` is unset.
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- Therefore: zero behaviour change in normal runs. 3× OFF cold runs
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are bit-identical (see `re-validation.md`).
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## Determinism under crowbar-on
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3× ON cold runs are bit-identical (`instructions=20000159`, identical
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fault PC/LR/CTR/r3/r4/r29/r30/r31, identical tid=16). The crowbar
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fires deterministically at the threshold instruction count, the 4
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spawned tids are bit-stable across runs, and the fault site is
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bit-stable.
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