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Taxonomy Rules

Objectives

  • Normalize noisy verification outputs into consistent:
  • severity
  • category
  • tags[]
  • Provide deterministic, explainable mapping from source text → taxonomy

Taxonomy Categories (v1)

FailureEvent.category enum:

  • assertion
  • scoreboard
  • protocol
  • timeout
  • xprop
  • compile
  • elab
  • runtime
  • unknown

Severity Mapping (v1)

UVM Severity Normalization

Map to:

  • UVM_INFO → info
  • UVM_WARNING → warning
  • UVM_ERROR → error
  • UVM_FATAL → fatal

If a simulator prefixes errors differently (e.g., *E, in Xcelium), map to error unless fatal keywords exist.

cocotb Severity Normalization

  • Exception in test → error
  • Explicit assertion failure → fail at test level, but failure events often still error unless you distinguish "check failure" vs "infrastructure error"

Recommended: - If message matches AssertionError, ScoreboardMismatch, or user "expect" failure → error but category scoreboard/protocol/assertion as appropriate - If matches ImportError, RuntimeError at harness, SimulatorError → runtime + severity fatal (configurable)

Category Mapping Rules (ordered, first match wins)

Rule Group A: Compile / Elaboration (highest priority)

1. Compile

Patterns: - Compilation failed - Error-[A-Z0-9]+ with compile - vlog- / xmvlog errors - Syntax error, unexpected token, Undefined variable in compile context

Category: compile
Tags: ["compile"] + vendor tags

2. Elaboration

Patterns: - Elaboration failed - Unresolved reference (during elab) - Cannot find instance / binding failed - Top module not found

Category: elab
Tags: ["elab"]

Rule Group B: Assertions

3. Assertion Failures

Patterns: - ASSERTION FAILED - SVA and failed - assert property failure messages - Vendor-specific: - Questa: ** Error: (vsim-*) with assertion wording - VCS: Assertion failure / $assertoff contexts

Category: assertion
Tags: ["assertion", "sva"] + protocol tags if detectable (AXI/APB/etc.)

If an assertion name is captured, attach it to: - AssertionFailure.assertion_id (when resolvable) - FailureEvent.tags += ["assert:<name>"] (bounded)

Rule Group C: Timeouts / Deadlocks

4. Timeout

Patterns: - TIMEOUT - watchdog - No activity for - objection timeout - phase timeout - simulation time limit reached

Category: timeout
Tags: ["timeout"] + phase tags if known (e.g., phase:run)

Rule Group D: X-Propagation / Unknowns

5. Xprop / X-Check

Patterns: - X-propagation - X-check - Unknown value X - has Xs - xrun: *E combined with X warnings (vendor-specific)

Category: xprop
Tags: ["xprop"]

Rule Group E: Scoreboard / Data Mismatches

6. Scoreboard Mismatch

Patterns: - scoreboard and (mismatch|compare failed|unexpected|expected) - DATA MISMATCH - CRC mismatch (often protocol too; see tags) - sequence item mismatch

Category: scoreboard
Tags: ["scoreboard"] + protocol tags if detectable

Rule Group F: Protocol Violations (when explicit)

7. Protocol

Patterns: - protocol violation - handshake violation - illegal transition - unexpected response (when not scoreboard compare) - BRESP/RRESP error codes in AXI monitors - APB PSLVERR in monitor

Category: protocol
Tags: ["protocol"] + protocol name tags

Rule Group G: Runtime/Infrastructure

8. Runtime

Patterns: - segmentation fault - core dumped - Simulator terminated - Python traceback that indicates harness failure - Out of memory - License checkout failed

Category: runtime
Severity: fatal for crashes/license failures; otherwise error
Tags: ["runtime"]

Default

9. Unknown

Category: unknown
Tags: derived from heuristic keyword extraction (bounded)

Tagging System (v1)

  • Vendor: vcs, questa, xcelium, verilator, riviera
  • Framework: uvm, cocotb
  • Protocol: axi4, ahb, apb, pcie, usb, jtag, i2c, spi, gpio
  • Phase: phase:build, phase:connect, phase:run, phase:shutdown
  • Component role: driver, monitor, scoreboard, sequencer

Protocol Detection Heuristics

If message contains:

  • AXI or AWVALID/WREADY/BRESP → tag axi4
  • PADDR/PSEL/PREADY/PSLVERR → tag apb
  • HADDR/HREADY/HRESP → tag ahb
  • LTSSM, TS1, TS2 → tag pcie
  • LFPS, PIPE, U0/U1/U2 → tag usb
  • TMS, TCK, TDO, TDI → tag jtag

Bounded Tagging

  • Max tags per failure: 20
  • Prefer deterministic ordering: [category/framework/protocol/vendor/phase/component_role/other]

Evidence Linkage Policy

When a taxonomy decision is made, the indexer may store:

  • taxonomy_reason: a short code like RULE_ASSERTION_VENDOR_QUES (optional internal field)
  • This reason is not required to be exposed via MCP in v1, but helps debugging

Implementation Reference

See sentinel_dv/taxonomy_engine.py for the canonical implementation.