uvm_config_db

The uvm_config_db class is the recommended way to access the resource database.

A resource is any piece of information that is shared between more than one component or object.

We use uvm_config_db::set to put something into the database and uvm_config_db::get to retrieve information from the database.

The uvm_config_db class is parameterized, so the database behaves as if it is partitioned into many type-specific "mini databases."

There are no limitations on the the type - it could be a class, a uvm_object, a built in type such as a bit, byte, or a virtual interface.

There are two typical uses for uvm_config_db. The first is to pass virtual interfaces from the DUT to the test, and the second is to pass configuration classes down through the testbench.

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	/***************************************************
	***** SET Method
	***************************************************/
	static function void set( uvm_component cntxt,
	string inst_name,
	string field_name,
	T value
	);
	// set function cannot return any value as its return type is "void".
	// So we cannot use if condition to check whether set is successfully
	// done or not.
	The full signature of the set method is
	void uvm_config_db #( type T = int )::set( uvm_component cntxt ,
	string inst_name ,
	string field_name ,
	T value );

view raw uvm_config_db1.sv hosted with ❤ by GitHub

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	/***************************************************
	***** GET Method
	***************************************************/
	static function bit get( uvm_component cntxt,
	string inst_name,
	string field_name,
	inout T value
	);
	// The method returns 1 if it is successful and
	// 0 if there is no such resource of this type at this location.
	The full signature of the get method is
	bit uvm_config_db #( type T = int )::get( uvm_component cntxt ,
	string inst_name ,
	string field_name ,
	ref T value );
	// value is the thing which is going to be retreived from the database.
	// If the call to get is successful, this value will be overwritten.
	// (that's why we use keyword "ref" here).

view raw uvm_config_db2.sv hosted with ❤ by GitHub

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/*****************ARGUMENTS*****************/

T is the type of the element being configured - usually a virtual interface or a configuration object.

cntxt and inst_name together form a scope that is used to locate the resource within the database.

The scope is formed by appending the instance name to the full hierarchical name of the context.

{cntxt, ".", inst_name}. or {cntxt.get_full_name(),".",inst_name}. //need to confirm

If cntxt is null then inst_name provides the complete scope information of the setting.

field_name is the key through which you can store and get that particular object.

field_name must be same during get & set, because while getting from uvm_databse it will find for field_name.

value is the thing or resource which is actually going to be put into the database.

value name can be different but value type must be same for get and set.

Both inst_name and field_name may be glob style or regular expression style expressions.

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	// ---------- Example1: ----------
	// FROM TOP file
	interface ahb_if data_port_if( clk , reset );
	uvm_config_db #( virtual ahb_if )::set( null , "*" , "data_port" , data_port_if );
	//-------Example1:
	// Here in inst_name, we use "uvm_test_top" because it is more precise and more efficient than "*".
	// This will always work unless your top level test does something other than super.new(name, parent)
	// in the constructor of your test component.
	// If you do something different in your test component, you will have to adjust the instance name accordingly.
	interface ahb_if control_port_if( clk , reset );
	uvm_config_db #( virtual ahb_if )::set( null , "uvm_test_top" , "control_port" , control_port_if );
	//-------Example2:
	// We can use uvm_root::get() variable also.
	uvm_config_db #( virtual ahb_if )::set( uvm_root::get(), "uvm_test_top" , "control_port" , control_port_if );
	//-------Example3:
	// We can set multiple instance of interface from TOP using generate block.
	interface Tx_intf[3];
	generate
	genvar i;
	for( i = 0; i < 3; i++) begin : TxifConfig
	initial begin
	// Set Virtual Interface to Database
	uvm_config_db#(virtual Tx_intf)::set(uvm_root::get(), "*", $sformatf("Tx_if[%0d]", i), Tx_if[i]);
	end
	end : TxifConfig
	endgenerate

view raw uvm_config_db3.sv hosted with ❤ by GitHub

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	//---------- Example2: ------------
	//-------Example4:
	// Get multiple instance of interface in class (Ex: env) using any LOOP (Ex: for, while)
	interface Tx_intf[3];
	...
	for (int unsigned i=0; i < 3; i++) begin
	if (!uvm_config_db #(router_Tx_agent_config)::get (this, "", $sformatf("Tx_cfg[%0d]", i), Tx_cfg[i]))
	`uvm_fatal ("NO-Tx_agnt_cfg", "agent config must be set for this class")
	end
	//-------Example5:
	// We can set mulitple instance of configuration object from TEST_CASE using LOOP (for, while)
	router_Tx_agent_config Tx_cfg[];
	...
	// allocate memory to dynamic array of configuration object from test_case build_phase
	for (int unsigned i=0; i<3; i++)
	Tx_cfg[i] = new ($sformatf("Tx_cfg[%0d]", i));
	// set Tx_agent_config from test_case build_phase
	for (int unsigned i=0; i<3; i++)
	uvm_config_db #(router_Tx_agent_config)::set (null, "*", $sformatf("Tx_cfg[%0d]", i), Tx_cfg[i]);
	//get Tx_agent_config in env build_phase
	for (int unsigned i=0; i<3; i++) begin
	if (!uvm_config_db #(router_Tx_agent_config)::get (this, "", $sformatf("Tx_cfg[%0d]", i), Tx_cfg[i]))
	`uvm_fatal ("NO-Tx_agnt_cfg", "agent config must be set for this class")
	end
	//-------Example6:
	//We set configuration objects from ENV
	router_Tx_agent_config Tx_cfg[3];
	// set agent config for agents
	for (int unsigned i=0; i<`RxNUM; i++) begin
	uvm_config_db #(router_Tx_agent_config)::set (null, $sformatf("Tx_agnt[%0d]", i), $sformatf("Tx_cfg[%0d]", i), Tx_cfg[i]);
	end
	// We get configuration objects in AGENT
	// Handle of agent config
	router_Tx_agent_config Tx_cfg;
	// get agent_config
	if (!uvm_config_db #(router_Tx_agent_config)::get (this, "", $sformatf("Tx_cfg[%0d]", idx), Tx_cfg))
	`uvm_fatal ("NO-Tx_agnt_cfg", "agent config must be set for this class")
	// 3rd argument field_name must be same in get and set.
	//"idx" is agent_id set by env.
	// build child components
	//for (int unsigned i = 0; i < env_cfg.num_of_Tx_agent; i++) begin
	// Tx_agnt[i] = router_Tx_agent::type_id::create($sformatf("Tx_agnt[%0d]", i), this);
	// Tx_agnt[i].idx = i;
	//end

view raw uvm_config_db4.sv hosted with ❤ by GitHub

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	//-------Example7:
	// We use "m_ahb_agent*" to ensure that we config both the agent and its children.
	// Without the '*' we would only configure the agent itself and not the driver, sequencer and monitor inside it.
	uvm_config_db #( ahb_agent_config )::set( null , "m_ahb_agent*" , "ahb_agent_config" , ahb_agent_config_h );
	//-------Example8:
	if( !uvm_config_db #( virtual ahb_if )::get( this , "" , "data_port" , m_cfg.m_data_port_config.m_ahb_if ) ) begin
	`uvm_error("Config Error" , "uvm_config_db #( virtual ahb_if )::get cannot find resource data_port" ) )
	end

view raw uvm_config_db5.sv hosted with ❤ by GitHub

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Precedence:

Build Phase:

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	/*****************PRECEDENCE at BUILD TIME*****************/
	// If a setting is made at build time, the cntxt hierarchy is
	// used to determine the setting's precedence in the database.
	// Settings from hierarchically higher levels have higher precedence.
	// Settings from the same level of hierarchy have a last setting wins
	// semantic.
	// A precedence setting of "uvm_resource_base::default_precedence" is
	// used for uvm_top,
	// and each hierarcical level below the top is decremented by 1.
	// Example1:
	// take one variable "int var1".
	// We set this variable from build_phase of test_case with value 70.
	var1 = 70;
	uvm_config_db #(int)::set (this, "*", "var1", var1);
	// We set this variable from build_phase of env with value 60.
	var1 = 60;
	uvm_config_db #(int)::set (this, "*", "var1", var1);
	// We set this variable from build_phase of agent with value 40.
	var1 = 40;
	uvm_config_db #(int)::set (this, "*", "var1", var1);
	// We get this variable in build_phase of driver.
	uvm_config_db #(int)::get(this, "", "var1", var1);
	$display("DRIVER var1=%0d", var1);
	//OutPut of $display Statement is 70. (highest hierarchy win)
	// (Settings from hierarchically higher levels have higher precedence)
	//Example2:
	// take one variable "int var1".
	// We set this variable from build_phase of test_case with value 70.
	var1 = 70;
	uvm_config_db #(int)::set (null, "*", "var1", var1);
	// We set this variable from build_phase of env with value 60.
	var1 = 60;
	uvm_config_db #(int)::set (null, "*", "var1", var1);
	// We set this variable from build_phase of agent with value 40.
	var1 = 40;
	uvm_config_db #(int)::set (null, "*", "var1", var1);
	// We get this variable in build_phase of driver.
	uvm_config_db #(int)::get(this, "", "var1", var1);
	$display("DRIVER var1=%0d", var1);
	// OutPut of $display Statement is 40. (highest hierarchy win)
	// (Settings from hierarchically higher levels have higher precedence)
	// Here during set we have not give any cntxt hierarchy,
	// so it will get form its parent.
	// If its parent had not set any value then child will get
	// value from its parent's parent and so on...

view raw uvm_config_db_build1.sv hosted with ❤ by GitHub

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Example1:

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	`include "uvm.sv"
	import uvm_pkg :: *;
	class my_agent extends uvm_agent;
	`uvm_component_utils (my_agent)
	int var1;
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	`uvm_error ("GET-FAIL", "not able to get value")
	else
	`uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	endtask
	endclass
	/////////////////
	class my_env extends uvm_env;
	`uvm_component_utils (my_env)
	int var1;
	my_agent agnt;
	function new (string name = "my_env", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	agnt = my_agent::type_id::create("angt", this);
	var1 = 60;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	endtask
	endclass
	/////////////////
	class my_test extends uvm_test;
	`uvm_component_utils (my_test)
	int var1;
	my_env env;
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	env = my_env::type_id::create("env", this);
	var1 = 70;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	phase.raise_objection(this);
	#500;
	phase.drop_objection(this);
	endtask
	endclass
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO top.sv(63) @ 0: uvm_test_top [SET] From TEST=70
	// UVM_INFO top.sv(41) @ 0: uvm_test_top.env [SET] From ENV=60
	// UVM_INFO top.sv(19) @ 0: uvm_test_top.env.angt [GET-PASS] var1=70

view raw uvm_config_db_build_null.sv hosted with ❤ by GitHub

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 Example2:

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	`include "uvm.sv"
	import uvm_pkg :: *;
	class my_agent extends uvm_agent;
	`uvm_component_utils (my_agent)
	int var1;
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	// if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	// `uvm_error ("GET-FAIL", "not able to get value")
	// else
	// `uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	#80;
	if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	`uvm_error ("GET-FAIL", "not able to get value")
	else
	`uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_env extends uvm_env;
	`uvm_component_utils (my_env)
	int var1;
	my_agent agnt;
	function new (string name = "my_env", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	agnt = my_agent::type_id::create("angt", this);
	// var1 = 60;
	// uvm_config_db #(int)::set(this, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	// #75;
	#60
	var1 = 60;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_test extends uvm_test;
	`uvm_component_utils (my_test)
	int var1;
	my_env env;
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	env = my_env::type_id::create("env", this);
	// var1 = 70;
	// uvm_config_db #(int)::set(this, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	phase.raise_objection(this);
	#70;
	var1 = 70;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	#500;
	phase.drop_objection(this);
	endtask
	endclass
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO top.sv(55) @ 60: uvm_test_top.env [SET] From ENV=60
	// UVM_INFO top.sv(82) @ 70: uvm_test_top [SET] From TEST=70
	// UVM_INFO top.sv(28) @ 80: uvm_test_top.env.angt [GET-PASS] var1=70

view raw uvm_config_db_run_this.sv hosted with ❤ by GitHub

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Run Phase:

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	/*****************PRECEDENCE at RUN TIME (AFTER BUILD)*****************/
	// After build time, all settings use the default precedence
	// and thus have a last wins semantic.
	// So, if at run time, a low level component makes a runtime setting
	// of some field, that setting will have precedence over a setting
	// from the test level that was made earlier in the simulation.
	// Example1:
	// take one variable "int var1".
	// We set this variable from run_phase of test_case with value 70.
	#70;
	var1 = 70;
	uvm_config_db #(int)::set (null/this, "*", "var1", var1);
	// We set this variable from run_phase of env with value 60.
	#60;
	var1 = 60;
	uvm_config_db #(int)::set (null/this, "*", "var1", var1);
	// We get this variable from run_phase of agent.
	#80;
	uvm_config_db #(int)::get (this, "", "var1", var1);
	// Output:
	// We got Latest value. Here 70.
	// Example2:
	// take one variable "int var1".
	// We set this variable from run_phase of test_case with value 70.
	#70;
	var1 = 70;
	uvm_config_db #(int)::set (null/this, "*", "var1", var1);
	// We set this variable from run_phase of env with value 60.
	#75;
	var1 = 60;
	uvm_config_db #(int)::set (null/this, "*", "var1", var1);
	// We get this variable from run_phase of agent.
	#80;
	uvm_config_db #(int)::get (this, "", "var1", var1);
	// Output:
	// We got Latest value. Here 60.

view raw uvm_config_db_run1.sv hosted with ❤ by GitHub

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Example1:

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	`include "uvm.sv"
	import uvm_pkg :: *;
	class my_agent extends uvm_agent;
	`uvm_component_utils (my_agent)
	int var1;
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	// if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	// `uvm_error ("GET-FAIL", "not able to get value")
	// else
	// `uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	#80;
	if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	`uvm_error ("GET-FAIL", "not able to get value")
	else
	`uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_env extends uvm_env;
	`uvm_component_utils (my_env)
	int var1;
	my_agent agnt;
	function new (string name = "my_env", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	agnt = my_agent::type_id::create("angt", this);
	// var1 = 60;
	// uvm_config_db #(int)::set(this, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	// #75;
	#60
	var1 = 60;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_test extends uvm_test;
	`uvm_component_utils (my_test)
	int var1;
	my_env env;
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	env = my_env::type_id::create("env", this);
	// var1 = 70;
	// uvm_config_db #(int)::set(this, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	phase.raise_objection(this);
	#70;
	var1 = 70;
	uvm_config_db #(int)::set(this, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	#500;
	phase.drop_objection(this);
	endtask
	endclass
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO top.sv(55) @ 60: uvm_test_top.env [SET] From ENV=60
	// UVM_INFO top.sv(82) @ 70: uvm_test_top [SET] From TEST=70
	// UVM_INFO top.sv(28) @ 80: uvm_test_top.env.angt [GET-PASS] var1=70

view raw uvm_config_db_run_this.sv hosted with ❤ by GitHub

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 Example2:

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	class my_agent extends uvm_agent;
	`uvm_component_utils (my_agent)
	int var1;
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	// if(!uvm_config_db #(int)::get(null, "", "var1", var1))
	// `uvm_error ("GET-FAIL", "not able to get value")
	// else
	// `uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	#80;
	if(!uvm_config_db #(int)::get(this, "", "var1", var1))
	`uvm_error ("GET-FAIL", "not able to get value")
	else
	`uvm_info ("GET-PASS", $sformatf("var1=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_env extends uvm_env;
	`uvm_component_utils (my_env)
	int var1;
	my_agent agnt;
	function new (string name = "my_env", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	agnt = my_agent::type_id::create("angt", this);
	// var1 = 60;
	// uvm_config_db #(int)::set(null, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	// #75;
	#60;
	var1 = 60;
	uvm_config_db #(int)::set(null, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From ENV=%0d", var1), UVM_NONE)
	endtask
	endclass
	/////////////////
	class my_test extends uvm_test;
	`uvm_component_utils (my_test)
	int var1;
	my_env env;
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction
	function void build_phase (uvm_phase phase);
	super.build_phase (phase);
	env = my_env::type_id::create("env", this);
	// var1 = 70;
	// uvm_config_db #(int)::set(null, "*", "var1", var1);
	// `uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	endfunction
	task run_phase (uvm_phase phase);
	phase.raise_objection(this);
	#70;
	var1 = 70;
	uvm_config_db #(int)::set(null, "*", "var1", var1);
	`uvm_info ("SET", $sformatf("From TEST=%0d", var1), UVM_NONE)
	#500;
	phase.drop_objection(this);
	endtask
	endclass
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO top.sv(54) @ 60: uvm_test_top.env [SET] From ENV=60
	// UVM_INFO top.sv(81) @ 70: uvm_test_top [SET] From TEST=70
	// UVM_INFO top.sv(27) @ 80: uvm_test_top.env.angt [GET-PASS] var1=70

view raw uvm_config_db_run_null.sv hosted with ❤ by GitHub

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/*********************Guideline**************************/

1. Before set anything into database first allocates memory to them and then put into database using set method.