Handshake Protocols Across Domains: Mechanism

Mechanism to understand

Mechanism for Handshake Protocols Across Domains focuses on req/ack completion reliability, deadlock risk, backpressure behavior. The goal is to convert issue observations into mechanism-backed closure decisions.

Two-way handshakes guarantee delivery across asynchronous clocks when both request and acknowledge paths are synchronized and protocol invariants are enforced. Treat each warning as a behavior contract violation candidate, then prove whether it is real risk or tool noise.

• Classify crossing type and data criticality.

• State source/destination clock or reset relationship.

• Identify when protocol semantics dominate topology choice.

System flow

CDC/RDC SIGNOFF FLOW — Handshake Protocols Across Domains

crossing inventory + reset map
          |
          v
crossing classification (level/pulse/bus/reset)
          |
          v
structure + protocol + reset checks
          |
          v
critical issues + waiver review
          |
          v
fix / validate / regress / signoff

Req/Ack flow

SRC: req -----> DEST
SRC: <----- ack  DEST

Rules:
1) req stable until ack observed
2) req/ack each cross through synchronizer
3) no combinational loop across domains

Layer responsibilities

CDC/RDC OWNERSHIP LAYERS — Handshake Protocols Across Domains

layer                 owns                            common failure
------------------    -----------------------------   -----------------------------
design intent         crossing architecture           wrong topology selected
protocol semantics    req/ack, fifo, ordering        liveness/deadlock bugs
reset behavior        assert/deassert sequencing      boot instability
analysis setup        tool rules + waivers            false confidence
signoff governance    risk acceptance + dashboard     stale critical waivers

CDC/RDC deep dive

Protocol correctness is the bridge between structural clean and functional safe.

Concept diagram

PROTOCOL FLOW

intent -> transport protocol -> synchronization -> destination acceptance

Metric graph

PROTOCOL ISSUE BURNDOWN

open issues: 20 -> 11 -> 5 -> 0

Reports and artifacts

• FIFO pointer proofs

• req/ack liveness

• pulse miss checks

• protocol assertions

Mini case study

Async FIFO empty/full logic looked correct until gray decode mismatch appeared during reset overlap.

Debug branches

• Pointer sync audit

• formal liveness checks

• reset interaction review

Senior review question

Ask: what evidence proves this risk is closed for silicon, not just tool-clean?

Key takeaways

• State crossing class, assumptions, and owner with every issue.

• Run structural and dynamic regressions after each fix.

Common pitfalls

• Treating all warnings as equivalent risk.

• Waiving issues without containment evidence.

• Skipping reset and reconvergence stress after CDC fixes.

Mechanism deep dive

Two-way handshakes guarantee delivery across asynchronous clocks when both request and acknowledge paths are synchronized and protocol invariants are enforced.