UVM: message mechanism

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Conventional Systemverilog Regular use $display() Print information , and uvm Contains several specific printing methods , Details can be automatically printed , No need to reuse $display() Appoint

1. Message printing method

UVM All message printing methods come from uvm_report_object class , and uvm_component Class inherits from uvm_report_object class , So all of them component Both contain message printing methods and setting methods

Here are the prototypes of common methods , In fact, all methods are essentially called uvm_report, You can check the source code .

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_report_object.svh
class uvm_report_object extends uvm_object;	//...
virtual function void uvm_report( uvm_severity severity,
                                    string id,
                                    string message,
                                    int verbosity = (severity == uvm_severity'(UVM_ERROR)) ? UVM_LOW :
                                                    (severity == uvm_severity'(UVM_FATAL)) ? UVM_NONE : UVM_MEDIUM,
                                    string filename = "",
                                    int line = 0,
                                    string context_name = "",
                                    bit report_enabled_checked =0);
virtual function void uvm_report_info( string id,
					 string message,
					 int verbosity = UVM_MEDIUM,
					 string filename = "",
					 int line = 0,
    					 string context_name = "",
					 bit report_enabled_checked = 0);
  virtual function void uvm_report_warning( string id,
					    string message,
    					    int verbosity = UVM_MEDIUM,
					    string filename = "",
					    int line = 0,
    					    string context_name = "",
					    bit report_enabled_checked = 0);
  virtual function void uvm_report_error( string id,
					  string message,
   					  int verbosity = UVM_LOW,
					  string filename = "",
					  int line = 0,
   					  string context_name = "",
					  bit report_enabled_checked = 0);
  virtual function void uvm_report_fatal( string id,
					  string message,
   					  int verbosity = UVM_NONE,
					  string filename = "",
					  int line = 0,
   					  string context_name = "",
					  bit report_enabled_checked = 0);  
//...
endclass

Then the input variables are explained

● string id： Indicates that the message is printed ID, Can be used to inform the message control method , Which message to control

● string message： The message to be printed

● string filename ： The name of the file where the message is printed

● int line： Print the line number of the file where the message is located

1.1. int verbosity Filtration degree

Redundancy , Or called Filtration degree , Indicates the filter level of the message . The higher the filtration level , The easier it is not to display this message

As always parameter Constant means , Defined as

typedef enum{
    
	UVM_NONE = 0,
	UVM_LOW = 100,
	UVM_MEDIUM = 200,
	UVM_HIGH = 300,
	UVM_FULL = 400,
	UVM_DEBUG = 500
} uvm_verbosity;

various component All have their own Filtration threshold , The default is UVM_MEDIUM, If the filtering degree of a message ≤ Filtration threshold , Will print , Otherwise you don't print .

uvm_report Method specific input , Indicates the severity of the message or Security level

1.2. uvm_severity severity Security level

With parameter Constant means , Yes UVM_INFO、UVM_WARNING、UVM_ERROR and UVM_FATAL, Capital must be written.

Corresponding to uvm_report_info、uvm_report_warning、uvm_report_error and uvm_report_fatal Four ways .

If the security level is fatal After the message is printed , Stop the simulation immediately

1.3. Example

Here's an example

class my_driver extends uvm_driver;
	`uvm_component_utils("my_driver")
	function new(string name = "my_driver", uvm_component parent);
		super.new(name,parent);
	endfunction
	virtual task main_phase(uvm_phase phase);
		...
		uvm_report_info("data1","data is derived", UVM_LOW)				//ID by "data1", The printed content is "data is derived", The security level is UVM_INFO, The filtering level is UVM_LOW
		...
	endtask
endclass

The printed information formula is ：UVM_INFO From sv file ( Number of lines of message statements in the file )@ Print time : Indexes [ID Number ] Printed information

for example

UVM_INFO my_driver.sv(20)@48500000：drv[data1]data is drived

2. Message control

2.1. Filter grade control

That is, the filter level of some message statements is uniformly controlled

The function prototype , Be careful uvm_component Class in uvm_report_object Class adds the setting of hierarchical regression to all methods .

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_report_object.svh

// Get the filter level according to the security level 
function int get_report_verbosity_level(uvm_severity severity=UVM_INFO, string id="");
function int get_report_max_verbosity_level();

function void set_report_verbosity_level (int verbosity_level);
function void set_report_id_verbosity (string id, int verbosity);
function void set_report_severity_id_verbosity (uvm_severity severity,string id, int verbosity);

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_component.svh

function void set_report_verbosity_level_hier (int verbosity_level);
function void set_report_id_verbosity_hier (string id, int verbosity);
function void set_report_severity_id_verbosity_hier (uvm_severity severity,string id, int verbosity);

Example

env.i_agt.drv.get_report_verbosity_level();									// obtain drv Filtering threshold of 
env.i_agt.drv.set_report_verbosity_level(UVM_HIGH);							//drv The filtering threshold of is set to UVM_HIGH
env.i_agt.set_report_verbosity_level_hier(UVM_HIGH);						//i_agt And all the filtering thresholds of its child nodes are set to UVM_HIGH

env.i_agt.set_report_id_verbosity("drv",UVM_HIGH);							// Set up ID by "drv" Of component The filtration threshold of is UVM_HIGH
env.i_agt.set_report_id_verbosity("sqr",UVM_HIGH);							// obtain ID by "sqr" Of component The filtration threshold of is UVM_HIGH

env.set_report_id_verbosity_hier("i_agt",UVM_HIGH);							// obtain ID by "i_agt" And its son component The filtration thresholds of all are UVM_HIGH

2.2. Document control

The printed message can be saved in the log file

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_report_object.svh
  function int  get_report_file_handle(uvm_severity severity, string id);
  function void set_report_default_file (UVM_FILE file);
  function void set_report_id_file (string id, UVM_FILE file);
  function void set_report_severity_file (uvm_severity severity, UVM_FILE file);
  function void set_report_severity_id_file (uvm_severity severity, string id,
                                             UVM_FILE file);
                                             
//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_component.svh 

  function void set_report_id_file_hier (string id, UVM_FILE file);
  function void set_report_severity_file_hier (uvm_severity severity, UVM_FILE file);
  function void set_report_severity_id_file_hier (uvm_severity severity, string id,
                                             UVM_FILE file);

2.3. behavior control

That is to control the behavior of messages , It is also defined by enumerating constants

typedef enum
{
    
	UVM_NO_ACTION = 'b000000,				// No action 
	UVM_DISPLAY = 'b000001,					// display messages 
	UVM_LOG 	= 'b000010,					// write file 
	UVM_COUNT 	= 'b000100,					// Count to a certain value , And stop the simulation 
	UVM_EXIT 	= 'b001000,					// Exit simulation 
	UVM_CALL_HOOK = 'b010000,				// Call callback function 
	UVM_STOP = 'b100000						// Stop simulation 
} uvm_action_type;

The default behavior of each security level is shown in the following table

severity	default action
UVM_INFO	UVM_DISPLAY
UVM_WARNING	UVM_DISPLAY
UVM_ERROR	UVM_DISPLAY 丨 UVM_COUNT
UVM_FATAL	UVM_DISPLAY 丨 UVM_EXIT

through ** or |** Implementing the merging of actions

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_report_object.svh
  function int get_report_action(uvm_severity severity, string id);
  function void set_report_severity_action (uvm_severity severity,uvm_action action);
  function void set_report_id_action (string id, uvm_action action);
  function void set_report_severity_id_action (uvm_severity severity,
                                               string id, uvm_action action);

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_component.svh
  function void set_report_severity_action_hier (uvm_severity severity,uvm_action action);
  function void set_report_id_action_hier (string id, uvm_action action);
  function void set_report_severity_id_action_hier (uvm_severity severity,
                                               string id, uvm_action action);

Example

class comp1 extends uvm_component;
	`uvm_component_utils(comp1);
	function void build_phase(uvm_phase phase);
		f = $fopen("logfile",w);
		set_report_default_file (f);
		set_report_severity_action_hier(UVM_INFO,UVM_DISPLAY|UVL_LOG);
		set_report_severity_action_hier(UVM_ERROR,UVM_DISPLAY|UVL_LOG|UVM_COUNT);
endclass

UVM_COUNT

It means counting the end of simulation , It can be set as follows UVM_ERROR Count threshold of

function void set_report_max_quit_count(int max_count);

2.4. Safety class overload

`uvm_info, `uvm_warning, `uvm_error, `uvm_fatal Can be overloaded with each other , The methods involved are as follows

//...\questasim64_2020.1\verilog_src\uvm-1.2\src\base\uvm_report_object.svh
  function void set_report_severity_override(uvm_severity cur_severity,
  function void set_report_severity_id_override(uvm_severity cur_severity,
                                                string id, 
                                               uvm_severity new_severity);

env.i_agt.drv.set_report_severity_override(UVM_WARNING, UVM_ERROR);	// take drv be-all uvm_warning Replace with uvm_error
env.i_agt.drv.set_report_severity_id_override(UVM_WARNING, "my_driver", UVM_ERROR);	// Joined the id