1,000+ ASIC Interview Questions: SystemVerilog, UVM & RTL

DescriptionQ917

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Q917DVNVIDIAASIC interview problem

Fix event-loss and shared-state monitor bugs

TechniquesDVSystemVerilogConcurrencyRace conditions

DifficultyMedium

TopicVerification

LanguageSystemVerilog

Requirements4 checkpoints

Problem

A monitor starts waiting for interrupt only after write_start, but an earlier interrupt must cancel the next write. Concurrent task calls also share static locals. Identify and fix both bugs.

Starting declarationSystemVerilog

// Events: write_start, interrupt, reset
// Multiple re-entrant monitor calls may be active.

Example input and output

Use this case to check your interpretation

Input

interrupt at cycle 5; write_start at cycle 6

Output

The cycle-6 write is canceled and the pending interrupt is consumed

Explanation

A lifetime interrupt collector preserves the event before any write-specific task starts.

Requirements (4)

Capture interrupts continuously in persistent state or a queue.
Atomically consume a pending interrupt when a write begins.
Use automatic per-call storage or transaction objects.
Define reset to clear pending interrupts and cancel active work deterministically.