Hang and Deadlock Debug on Silicon: Inputs and Outputs

Inputs and outputs contract

Inputs and Outputs for Hang and Deadlock Debug on Silicon is anchored on Mean time to identify first stuck resource and classify issue as hang, livelock, or true deadlock.. Convert observed behavior into mechanism-backed and owner-bound actions.

INPUTS
  - board and fixture configuration state
  - firmware revision and boot arguments
  - corner conditions (V/F/T) and workload window
  - instrumentation profile and trace coverage assumptions

OUTPUTS
  - evidence-backed root-cause class
  - owner-signed mitigation proposal
  - replay validation matrix and rollback triggers
  - release recommendation

Ownership split

OWNERSHIP LAYERS - Hang and Deadlock Debug on Silicon

+----------------------+--------------------------------+--------------------------------+
| Team                 | Primary responsibility         | Closure artifact               |
+----------------------+--------------------------------+--------------------------------+
| NoC and fabric owner | hypothesis map and execution     | triage decision log            |
| firmware scheduler owner | stage behavior and software proof | boot/trace evidence packet     |
| power management owner | replay matrix and risk closure    | signoff memo + rollback gates  |
+----------------------+--------------------------------+--------------------------------+

Silicon bring-up deep dive

Triage quality is measured by how quickly teams converge from symptom to proven root-cause class with minimal collateral churn.

Concept diagram

TRIAGE CONVERGENCE

symptom -> classify -> isolate -> prove -> bounded fix -> replay

Metric graph

TRIAGE EFFECTIVENESS

wide speculative edits   ██████
classified bounded fixes █████████

Metrics and artifacts to collect

• time-to-classification

• first-failure artifact completeness

• hypothesis branch conversion rate

• post-fix recurrence trend

Mini case study

Intermittent field-like failures closed faster once teams forced one-variable branch tests and owner-tagged evidence packets.

Debug branches

• Preserve first-failure state before reruns.

• Use disproof-oriented experiments to collapse cause tree quickly.

• Promote fixes only after recurrence tracking windows pass.

Senior review question

Ask: what is the first failing boundary, which artifact proves it, and who owns bounded closure?

Key takeaways

• Tie every bring-up claim to one reproducible setup state and one proving artifact.

• Prefer bounded fixes with clear owner and rollback trigger over broad multi-variable edits.

Common pitfalls

• Running parallel uncontrolled experiments and losing causality.

• Declaring closure without replaying across representative corners.

• Escalating severity before bench/setup hypotheses are disproven.

Handoff explanation

Inputs should include board state, firmware hash, environment corner, and instrumentation profile.

Outputs should include owner-signed mitigation proposal and validation boundaries.