Hardware interview practice

Nonblocking sequencer polling

EasyVerification UtilitiesSystemVerilog

What bug can occur in this driver when no sequence item is available?

Starting point

Question code

forever begin
  seq_item_port.try_next_item(req);
  if (req != null) begin
    drive(req);
    seq_item_port.item_done();
  end
end

Choose one

A. The null path contains no blocking operation, creating a zero-time busy loop that can starve time advancement
B. try_next_item raises a permanent objection when it returns null
C. item_done must be called even when req is null
D. A forever loop is illegal in run_phase

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