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Asynchronous interrupt events handling

Technique WIKI v1 · 6/28/2026

Asynchronous interrupt events handling is a technique identified in the DifuzzRTL work as one of several RTL-fuzzing adaptations for CPU designs. In the paper’s abstract, it is listed alongside cycle-sensitive register-coverage guidance, a unified CPU input format with Tilelink protocols, and drop-in-replacement designs as a DIFUZZRTL technique developed to address unique RTL design characteristics.

Overview

Asynchronous interrupt events handling is presented in DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs as one of the specialized techniques used by DIFUZZRTL, an RTL fuzzer for CPU designs. The paper places this technique in the context of adapting fuzzing to the specific challenges of CPU RTL, where standard software-oriented fuzzing assumptions do not directly apply.[1][2]

Role in DIFUZZRTL

According to the abstract, DIFUZZRTL introduces several techniques tailored to "unique RTL design characteristics," and asynchronous interrupt events handling is explicitly listed as one of them. This indicates that the technique is part of the system’s design for exercising CPU RTL behavior under conditions relevant to interrupts that occur asynchronously with normal execution.[2]

The same abstract states that DIFUZZRTL is an RTL fuzzer intended to automatically discover unknown CPU bugs, using a register-coverage guided fuzzing technique to identify RTL state transitions efficiently and correctly. Within that broader design, asynchronous interrupt events handling is one of the named supporting techniques for CPU fuzzing.[1][2]

Evidence-backed scope

The provided evidence names this technique but does not describe its internal algorithm, data structures, triggering policy, or evaluation results in isolation. Therefore, based on the available source, it is safest to characterize asynchronous interrupt events handling as:

  • a named technique in the DIFUZZRTL methodology,[2]
  • intended for CPU RTL fuzzing,[1]
  • and motivated by unique RTL design characteristics.[2]

Context

The paper reports that DIFUZZRTL was evaluated on three open-source CPU RTLs—OpenRISC Mor1kx Cappuccino, RISC-V Rocket Core, and RISC-V Boom Core—and found 16 new bugs. However, the abstract does not attribute those findings to asynchronous interrupt events handling specifically.[3]

[1]: DIFUZZRTL is described as an RTL fuzzer for automatically discovering unknown bugs in CPU RTLs. [2]: The abstract explicitly lists asynchronous interrupt events handling as one of several new techniques developed for RTL-specific characteristics. [3]: The evaluation and bug counts are reported for DIFUZZRTL as a whole, not for this technique alone.

LINKED ENTITIES

2 links
DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs INTRODUCES
DiFuzzRTL IMPLEMENTS

CITATIONS

5 sources
5 citations
[1] Asynchronous interrupt events handling is named in the DifuzzRTL abstract as one of several new techniques developed for unique RTL design characteristics. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[2] DIFUZZRTL is an RTL fuzzer proposed to automatically discover unknown bugs in CPU RTLs. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[3] The abstract states that DIFUZZRTL uses a register-coverage guided fuzzing technique to identify RTL state transitions efficiently and correctly. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[4] The provided evidence does not describe the internal algorithm of asynchronous interrupt events handling; it only identifies it as a named technique within DIFUZZRTL. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs
[5] DifuzzRTL was evaluated on three open-source CPU RTLs and identified 16 new bugs, but the abstract does not attribute those results to asynchronous interrupt events handling specifically. DifuzzRTL: Differential Fuzz Testing to Find CPU Bugs