The training/firmware boundary needs a stable serialization for the
temporal head's weights, distinct from the kernel scaffold and the
firmware ABI. This commit defines that format on the host side. The
firmware-side mirrored loader lands when the toolchain unblocks.
Format:
- Header (24 B): magic 'RVNE' / version 1 / dtype flag
(FP32 / FP16) / input_dim / n_q_heads / n_kv_heads / head_dim /
n_layers / n_classes / weights_len.
- Body: weights_len bytes of flat per-layer weights.
- Footer (4 B): CRC32 IEEE 802.3 over everything before, same
polynomial used by temporal_task.c so a blob produced here parses
on the firmware unchanged.
Layout decisions:
- Little-endian throughout (Xtensa native).
- Weights kept as Vec<u8> rather than Vec<f32>/Vec<f16> so the no_std
firmware loader (which may not have the `half` crate) can mmap and
read either dtype directly.
- Versioning is hard-break: bumping `version` means firmware refuses
to load. Optional fields go behind reserved flag bits, never by
field reorder. Documented inline.
Validation surface:
- `WeightBlobHeader::validate()` catches zero dims, invalid GQA
ratios (n_q_heads % n_kv_heads != 0), n_layers=0, n_classes<2.
Same checks fire from `WeightBlob::parse()` so the firmware can't
accidentally accept a blob the host should have rejected.
- `WeightBlob::parse()` enforces magic / version / size / CRC
before exposing weights to the caller.
Tests (8/8 passing, alongside 5/5 sparse smoke = 13/13 total):
- roundtrip_fp32, roundtrip_fp16
- parse_rejects_bad_magic, _wrong_version, _size_mismatch,
_crc_corruption, _invalid_gqa_ratio_in_header
- header_constants_match_wire_layout (anchor)
What's deliberately NOT in this commit:
- The firmware-side mirrored loader (deferred to the iteration that
unblocks the esp Rust toolchain — no point shipping a parser that
can't be compiled).
- Per-layer weight ordering. The blob is a flat byte-buffer; the
interpretation of per-layer offsets is the kernel's contract,
documented in the eventual model module (ADR-095 §3.2 follow-up).
Co-Authored-By: claude-flow <ruv@ruv.net>
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