UVM_INFO dropping response for sequence 2, sequence not found. Probable cause: sequence exited or has been killed

UVM
, ,
1

I got the following message while the test is running:

UVM_INFO @ 2869937: uvm_test_top.uart_sa_env.uart_env.uart_agent.sequencer [Sequencer] Dropping response for sequence 2, sequence not found. Probable cause: sequence exited or has been killed

It’s a simple test which send only one item.

The relevant code in the test is:

   virtual task run_phase( uvm_phase phase );
      uvm_reg_data_t rx_data;
      uvm_status_e status;
      uart_wr_seq = uart_base_sequence::type_id::create("uart_wr_seq");
      phase.raise_objection(this);


      #100ns;
      `uvm_info(get_type_name(), {"write 1 to sys cgf reg ", get_full_name()}, UVM_LOW);
      m_ral_model.uartlcr_reg.write(status , 32'h209);
      #10ns;
      uart_wr_seq.start(uart_sa_env.uart_env.uart_agent.sequencer);      
      #5000ns;
      m_ral_model.uartdr_reg.read(status, rx_data);
      #10ns;
      `uvm_info({get_type_name," : ID"},$psprintf("rx_data is %f:",m_ral_model.uartdr_reg.get()),UVM_HIGH)

      $display("rx data is %f", rx_data);
      `uvm_info({get_type_name," : ID"},$psprintf("rx_data is %f:",rx_data),UVM_HIGH)

      //m_ral_model.uartdr_reg.write(status , 32'h1C);
      //#5000ns;
      //m_ral_model.uartdr_reg.write(status , 32'hFF);


   endtask //run ghase

What can cause the sequencer to exited?

2

In reply to Sarit8r:

It’s likely that the uart_wr_seq is operating in a different manner that the uart_driver. The sequence isn’t expecting a reply from the driver, so it finishes running. However, the driver is attempting to send a response to the sequence, but it no longer exists on the sequencer.

You will need to show the sequence and driver code for a better explanation.

3

In reply to cgales:

The relevant code in the driver was:

task uart_driver::main_loop();
    uvm_sequence_item item;
    uart_pkt_c pkt;

    forever begin
        seq_item_port.get(item);
        void'($cast(pkt, item));
        if(pkt==null) `uvm_fatal(get_name(), "casting failed or item returned null")
        if(pkt.dir==TX) tx_lock.get();
        else
           rx_lock.get();
        fork
        begin
            automatic uart_pkt_c req, rsp;
            req = pkt;
            if(req.dir==TX)
               send(req);
            else                      
               read(req);
            $cast(rsp, req.clone());
            rsp.set_id_info(req);
            seq_item_port.put(rsp);
            if(req.dir==TX) 
               tx_lock.put();
            else
               rx_lock.put();
        end
        join_none
    end
endtask

sequene code:

class uart_base_sequence extends uvm_sequence;
    `uvm_object_utils(uart_base_sequence)

    local uart_pkt_c pkt;     //reuse the constraint solver

    function new(string name = "uart_base_sequence");
        super.new(name);
        pkt = uart_pkt_c::type_id::create(get_name(),,get_full_name());
    endfunction : new

    virtual function void set_name (string name);
        super.set_name(name);
        pkt.set_name(name);
    endfunction


    
    virtual task body();
      `uvm_info(get_type_name(), "Call uart seq", UVM_LOW)
      `uvm_do_with(req, {data == 3; data_width == `DATA_WIDTH_8BIT; dir == TX; burst_length == 1;})
    endtask : body
endclass
`endif

The driver code is taken from a uart example in git.
It looks like that there in no code which end the item… so I guess it’s the problem.

I can use instead get_next_item, and item_done.