Specman e：一个序列驱动它的 BFM，它的 MAIN 也没有在测试中定义

Question

正在搭建串口验证环境。我有 2 个序列：

用于驱动 DUT UART 配置 - vr_ad_sequence
用于将帧驱动到 DUT UART Rx - uart_sequence

两个序列、它们的驱动程序和 BFM 都工作正常。但是，当我创建一个仅使用配置序列的简单测试时，DUT UART Rx 由验证环境驱动（也没有 MAIN uart_sequence 的扩展）！测试看起来像这样：

// The test that drives ALSO uart_sequence
extend MAIN vr_ad_sequence {  // Configuration sequence
   body()@driver.clock is only {
       // Configuration logic
   };
};

我成功阻止 Rx 被驱动的唯一方法是 "overwriting" MAIN uart_sequence body():

// The test that does not drives UART Rx
extend MAIN uart_sequence { // Rx sequence
    body() @driver.clock is only {
    };
};

extend MAIN vr_ad_sequence {  // Configuration sequence
   body()@driver.clock is only {
       // Configuration logic
   };
};

以下是 UART Rx 序列、驱动程序和 BFM 在验证环境中的定义方式：

sequence uart_sequence using 
   item           = uart_frame_s,
   created_driver = uart_driver_u;


extend uart_driver_u {
   event clock is only rise(port_clk$) @sim;
};


extend uart_rx_agent_u {
   driver: uart_driver_u is instance;
};


extend uart_rx_agent_u {
   uart_monitor : uart_rx_monitor_u is instance; // like uvm_monitor
   uart_bfm     : uart_rx_bfm_u is instance; // like uvm_bfm
};


extend uart_rx_bfm_u {
   !cur_frame: uart_frame_s;

   run() is also {
      start execute_items();
   };

   execute_items() @rx_clk is {
      while (TRUE) do{
         cur_frame = p_agent.driver.get_next_item();
         drive_frame(cur_frame);
      }; 
   }; 

   drive_frame(cur_frame : uart_frame_s) @rx_clk is {
       // Drive frame logic
   };
};

你知道为什么 uart_sequence 驱动它的 BFM 即使它的 MAIN 没有扩展吗？感谢您的帮助

Answer 1

在 Specman 文档中有一个示例和解释说明：

The MAIN sequence creates count sequences of any kind, randomly selected from the currently loaded ATM sequences.

MAIN 序列也在其自己的部分中进行了描述：

The MAIN sequence subtype is defined directly under the sequence driver, and is started by default. It is the root for the whole sequence tree.

它的代码是：

extend MAIN sequence_name {
    count: uint;
    !sequence: sequence_name;

    keep soft count > 0;
    keep soft count <= MAX_RANDOM_COUNT;
    keep sequence.kind not in [RANDOM, MAIN];

    body() @driver.clock is only {
        for i from 1 to count do {
            do sequence;
        };
    };
};

通过扩展它并覆盖它 body() 您将禁用启动随机序列的自动生成代码。

您还可以通过在 UART 序列驱动程序中限制 gen_and_start_main 来禁用 MAIN 序列。

Specman e：一个序列驱动它的 BFM，它的 MAIN 也没有在测试中定义

Specman e: A sequence drives its BFM also its MAIN was not defined in a test

uvm

specman

e