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Add CHANGES.md, README, update SPEC/ADRs for release 2

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- CHANGES.md: detailed changelog for release 1 and 2
- README.md: full project docs with install, probe, run, test usage
- SPEC.md: add ADR-0014~0017 references, update R7 for pcie_ep endpoint
- ADR-0003: update NOC description to reference ADR-0017
- ADR-0004: add HBM efficiency factor (0.8) to BW guarantee contract
- ADR-0014: status Proposed -> Accepted
- ADR-0015: update D4 to M_CPU bypass for Memory R/W, add ADR-0016/0017 links
- ADR-0016 (new): IOChiplet NOC and memory data path
- ADR-0017 (new): Cube NOC 2D mesh architecture
- Fix MD lint warnings (unfenced code blocks) across all docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Yangwook
2026-03-19 01:43:15 -07:00
parent d75da439c6
commit fc6abbc8ee
10 changed files with 613 additions and 65 deletions
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docs/adr/ADR-0004-memory-semantics-local-hbm.md
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@@ -21,8 +21,15 @@ Each PE has a notion of “local HBM” that must guarantee full HBM bandwidth,
### D2. Local HBM bandwidth guarantee contract
- Accesses from a PE to its local HBM MUST guarantee full HBM read/write bandwidth
independent of intervening fabric bandwidth limits.
- Accesses from a PE to its local HBM MUST guarantee full effective HBM
read/write bandwidth independent of intervening fabric bandwidth limits.
- Effective HBM bandwidth = spec bandwidth x efficiency factor.
The efficiency factor (configured via `hbm_ctrl.attrs.efficiency`, default 0.8)
models real-world DRAM inefficiencies (refresh cycles, bank conflicts, page
misses). For example: 256 GB/s spec x 0.8 = 204.8 GB/s effective.
- The topology builder applies the efficiency factor to xbar-to-hbm edge
bandwidth at graph construction time, so all downstream routing and latency
computation uses the effective value.
- This guarantee is modeled by:
- a dedicated logical path and/or service model that enforces HBM BW at the PE-local-HBM interaction point,
- while still incurring non-zero latency along explicitly modeled components.
@@ -62,3 +69,4 @@ Tests should cover:
- SPEC R2/R5
- ADR-0002 (distance/order & explicit bypass)
- ADR-0017 D7 (PE DMA data paths through NOC to HBM)