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Finite state machine state transition identification

Technique WIKI v1 · 6/28/2026

Finite state machine state transition identification is a technique referenced in DIFUZZRTL for RTL fuzzing. In that context, register-coverage guided fuzzing is used to efficiently and correctly identify state transitions in the finite state machines of RTL designs, helping guide testing of CPU RTL implementations.

Finite state machine state transition identification

Finite state machine state transition identification is a technique used in RTL fuzzing to determine when an RTL design's finite state machine has moved from one state to another. In the DIFUZZRTL work, this capability is part of a register-coverage guided fuzzing approach that is described as efficiently and correctly identifying state transitions in RTL finite state machines.[1]

Context in DIFUZZRTL

DIFUZZRTL is an RTL fuzzer for discovering bugs in CPU RTL designs. Its abstract states that the system "develops a register-coverage guided fuzzing technique" and that this technique "efficiently yet correctly identifies a state transition in the finite state machine of RTL designs."[1] This places finite state machine state transition identification as a supporting technique within coverage-guided RTL fuzzing rather than as a standalone end-user tool.

Role

Based on the available evidence, the main documented role of this technique is:

  • to support register-coverage guided fuzzing for RTL designs; and
  • to do so in a way intended to be both efficient and correct when identifying finite state machine state transitions.[1]

Evidence scope

The provided source does not describe the internal algorithm for how the state transition identification is performed. It only establishes that DIFUZZRTL uses this capability as part of its RTL fuzzing methodology.[1]

[1]: DIFUZZRTL abstract, provided evidence.

CITATIONS

3 sources
3 citations
[1] DIFUZZRTL develops a register-coverage guided fuzzing technique that efficiently and correctly identifies state transitions in the finite state machines of RTL designs. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[2] Finite state machine state transition identification is used in the context of RTL fuzzing for CPU RTL designs in DIFUZZRTL. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[3] The available evidence does not provide the internal algorithm for the state transition identification technique; it only states its purpose and use within DIFUZZRTL. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs