bhx

# Changelog

Notable changes per release. Format loosely follows
[Keep a Changelog](https://keepachangelog.com/en/1.1.0/);
this project does not yet promise SemVer compatibility on the RPC
wire format or library API surface (we're not 1.0).

## Unreleased

V2 virtio-dispatch redesign. The kick ring + completion ring + host-
side throttle that grew up around #184 are gone; in their place is a
per-(slot, queue) dirty bitmap in BRISC L1. The bitmap is level-
sensitive — guest QUEUE_NOTIFY storms coalesce into a single set
byte, so the dispatch path can't fall behind under any burst. Wire
incompatible with 0.9.0; `TENSIX_PROTOCOL_VERSION` bumped 4 → 5.

### Added

- **V2 dirty-bitmap dispatch** (`#187` / `#188` / `#189`). BRISC
  writes 1 to `CTRL_OFF_DIRTY[slot][queue]` on every guest
  QUEUE_NOTIFY; the daemon's `Dispatcher` clears the byte and
  dispatches each pass. Replaces V1's 2048-entry kick ring +
  daemon-side `consume_kick_ring_pass` consumer.
- **V2 processed-cursor table** at `CTRL_OFF_PROCESSED`. Daemon
  publishes `used.idx` after each successful dispatch so
  warm-resume reads cursors directly without re-probing guest
  DRAM.
- **`bhx_notify_events_total`, `bhx_dispatch_passes_total`,
  `bhx_dispatch_queues_drained`** Prometheus counters surface the
  new dispatch path. The burst regression test (`scripts/
  soak_virtio_burst.py`) asserts `dispatch_passes_total > 0` to
  confirm the workload reached the new path.
- **`scripts/soak_virtio_burst.py`** — multi-queue burst regression
  test. Sustains 16-job direct=1 fio randwrite + a tight
  `printf` loop to `/dev/console`, samples `/metrics` every 1 s,
  and verifies the daemon log contains zero
  `kick.*drop|rescue|throttle.*ENGAGE` matches.
- **`DaemonState.chip_reset_this_session`** flag — gates
  `maybe_opportunistic_reset_board` so 4-way parallel cold boots
  reset the chip exactly once, not once per L2CPU. Without this
  the second-and-later resets blip the chip while earlier-booted
  L2CPUs hold mmap pages, SIGBUSing their workers.
- **`Dispatcher` (was `KickPoller`)** with documented testability
  seam (`CtrlL1Access` trait); `drain_dirty_bitmap` is unit-tested
  against an in-memory L1 fake covering all five visit/clear
  semantics cases plus the address-formula pins.

### Changed

- **`KickPoller` → `Dispatcher`**, plus `kick_poller` → `dispatcher`
  field on `DaemonState`, `tensix-kick-poller` → `tensix-dispatcher`
  thread name, `[kick-poller]` → `[dispatcher]` log tag,
  `kicks_consumed` → `dispatches_total`,
  `last_kick_slot_queue` → `last_dispatch_slot_queue`. Pure
  rename; no behavior change. V1 vocabulary scrubbed throughout
  the codebase (firmware, daemon, scripts, docs).
- **`CTRL_SIZE` shrinks 36 KiB → 4 KiB**. V2 footprint is ~1.5 KiB;
  the rest is reserved for future fields.
- **Stats-page offsets repacked** — V1 `STATS_OFF_KICK_DROPS`,
  `STATS_OFF_COMPL_EVENTS`, `STATS_OFF_LAST_COMPL` retired with
  V1 (#190); deprecated PRECAP / BLINDCAP / POSTCAP slots dropp