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Hardware interview practice

How a UVM Analysis Port Works

EasyUVM ComponentsMultiple choice

Which statement best describes uvm_analysis_port::write?

Answer choices

  1. A. It is a zero-time, synchronous transaction-level modeling (TLM) broadcast to zero or more connected subscribers
  2. B. It blocks until every subscriber calls item_done
  3. C. It arbitrates among sequences and grants exactly one subscriber
  4. D. It creates a deep copy for every subscriber

Concise answer

The answer and the key reason

`uvm_analysis_port::write` distributes one transaction handle to every connected subscriber without a return handshake. It is a function-based observation broadcast, permits zero subscribers, performs no arbitration, and does not automatically clone the transaction for each recipient.

Deeper explanation

Work through the implementation and tradeoffs

Analysis ports model fan-out from producers such as monitors to consumers such as scoreboards, coverage collectors, and loggers. A single `write` invocation forwards the same published item through all connected analysis implementations. Because `write` is a function, subscribers cannot consume simulation time or wait for an `item_done` response.

The transmitted value is an object handle rather than an automatic snapshot. If the producer later mutates a reused transaction, consumers that retained that handle may observe the changed data. A verification environment should therefore define an ownership policy, such as creating a fresh object for every publication or cloning at an agreed boundary.

What to remember

  • Broadcasts to all subscribers
  • No completion handshake
  • Handles are not cloned

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