CSR-transition coverage metric
TechniqueThe CSR-transition coverage metric is a hardware-fuzzing guidance signal introduced in ProcessorFuzz for RTL processor verification. It monitors transitions in Control and Status Registers (CSRs) and treats those transitions as indicators of new processor states, enabling HDL-agnostic feedback without requiring instrumentation of the processor design.
First seen 6/24/2026
Last seen 6/29/2026
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Overview
The CSR-transition coverage metric is a coverage-guidance technique for processor fuzzing at the Register-Transfer Level (RTL). It was introduced in ProcessorFuzz as a way to guide fuzzing using transitions in Control and Status Registers (CSRs).
Motivation
NEIGHBORHOOD
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6 connectionsProcessorFuzz employs the CSR-transition coverage metric as its feedback signal to explore new processor states.
The proposed metric serves as the coverage signal guiding the fuzzer, addressing issues with prior coverage signals.
Along with the tool, the paper proposes a new coverage metric based on CSR transitions.
The metric is defined by observing transitions in CSRs to indicate new processor states.
The tool’s guidance mechanism is the CSR-transition coverage metric.
The metric is defined by observing transitions in CSRs, so it relies on the CSR concept.
CITATIONS
6 sources6 citations — click to expand
[1] The CSR-transition coverage metric was introduced as part of ProcessorFuzz for hardware fuzzing of RTL processor designs. ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI
[2] Prior hardware-fuzzing works are described as suffering from lack of support for widely used HDLs and from misleading coverage signals that misidentify interesting inputs. New Processor Fuzzing Mechanism
[3] ProcessorFuzz monitors transitions in Control and Status Registers, and CSRs are described as controlling and holding processor state. ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI
[4] Transitions in CSRs are treated as indicating a new processor state, and guiding the fuzzer with this feedback enables exploration of new processor states. New Processor Fuzzing Mechanism
[5] The approach is HDL-agnostic and does not require instrumentation in the processor design, allowing support for RTL designs written in different hardware languages. ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI
[6] In evaluation on Rocket, BOOM, and BlackParrot, ProcessorFuzz triggered a set of ground-truth bugs 1.23× faster on average than DIFUZZRTL and exposed 8 new bugs across the three RISC-V cores plus 1 new bug in a reference model; all nine were confirmed by developers. ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI