Error Injection and Negative Testing: Inputs and Outputs

Inputs and outputs contract

Inputs and Outputs for Error Injection and Negative Testing focuses on negative-test coverage closure and DUT error-response pass rate. The purpose is to turn memory observations into mechanism-backed actions with explicit owners and release-safe validation.

Use this contract for architecture, controller firmware, PHY, and validation handoffs. Missing inputs create expensive late-stage rework and inconclusive debug loops.

INPUTS
  - workload distribution and QoS target
  - firmware revision, controller policy profile, timing registers
  - data-rate / voltage / temperature operating state
  - training snapshot and reliability policy status

OUTPUTS
  - bottleneck classification with command-level evidence
  - owner-signed mitigation proposal
  - before/after trend for latency, bandwidth, and reliability
  - regression matrix with rollback triggers

Ownership split

MEMORY OWNERSHIP LAYERS - Error Injection and Negative Testing

artifact area     owner
----------------  ----------------------------
architecture    VIP architect
controller FW   verification lead
verification    protocol owner
silicon bringup compliance engineer

Rule: every signoff metric has a named accountable owner.

VIP deep dive

SVA and procedural checkers, temporal protocol rules, error-injection validation, and debug strategies for high-signal protocol closure.

Concept diagram

VIP SECTION - Protocol Checkers & Assertion Strategy

testcase -> agents -> checkers -> coverage -> evidence

Metric graph

checker noise vs real violations trend

Reports and artifacts

• checker hit report

• coverage closure sheet

• compliance trace matrix

• regression health snapshot

Mini case study

A profile drift caused false checker storms until configuration hashes were locked in CI.

Debug branches

• Reproduce with locked seed and profile

• Isolate checker vs scoreboard vs DUT paths

• Map failure to spec clause and owner

Senior review question

Ask: which latency, bandwidth, and reliability evidence proves this VIP topic is closed under real traffic?

Key takeaways

• Always tie controller and PHY counter shifts to application latency and throughput outcomes.

• Lock firmware timing profile, thermal condition, and DIMM state before comparing VIP captures.

Common pitfalls

• Chasing peak bandwidth while ignoring p99 latency and fairness tails.

• Changing timing guardbands without separating SI noise from scheduling issues.

• Declaring closure without reliability gates, fault injection, and regression replay.

VIP atlas notes

Error Injection and Negative Testing should be read as an end-to-end VIP behavior, not as a single block definition. Production compliance closure reflects interactions between agents, checkers, coverage, and customer evidence before tapeout or IP release claims.

Compliance requires proving correct behavior under illegal stimulus, parity/ECC faults, timeout paths, and recovery sequences. Error-injection checkers validate that monitors, scoreboards, and DUT responses remain coherent when the bus enters degraded modes. VIP inefficiency is multiplicative: one weak checker enable, one hollow coverage bin, or one non-reproducible failure repeated across regressions can dominate signoff risk.