Drop all objection manually in UVM

Test requirement is like,

1) When polling for more than one interrupts by continuously reading different registers in parallel and based on some indication move to next phase of UVM

2) Waiting for some timer to be expired and then moving to next phase of UVM

Let’s take one scenario where,

Driver is raising objection but never dropping objection and requirement is to move to next phase (extract_phase) after #50 timeunit. But because all the objection are not dropped in run_phase, simulation is not going to extract_phase.

Let’s go through example.

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	class my_seq_item extends uvm_sequence_item;
	rand bit [31:0] data;
	rand bit [7:0] addr;
	`uvm_object_utils_begin(my_seq_item)
	`uvm_field_int(addr, UVM_DEFAULT | UVM_HEX)
	`uvm_field_int(data, UVM_DEFAULT | UVM_HEX)
	`uvm_object_utils_end
	function new (string name = "my_seq_item");
	super.new(name);
	endfunction : new
	function string convert2string();
	convert2string = $sformatf("addr:0x%h, data:0x%h", addr, data);
	return convert2string;
	endfunction : convert2string
	endclass : my_seq_item
	class my_seq extends uvm_sequence#(my_seq_item);
	`uvm_object_utils(my_seq)
	function new (string name = "my_seq");
	super.new(name);
	endfunction : new
	task body();
	`uvm_create(req)
	start_item(req);
	if (!req.randomize()) begin
	`uvm_fatal(get_name(), $sformatf("Randomization of %s failed", req.get_type_name()))
	end
	finish_item(req);
	endtask : body
	endclass : my_seq
	class my_seqr extends uvm_sequencer#(my_seq_item);
	`uvm_component_utils(my_seqr)
	function new (string name = "my_seqr", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	endclass : my_seqr
	class my_driver extends uvm_driver#(my_seq_item);
	`uvm_component_utils(my_driver)
	function new (string name = "my_driver", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	forever begin
	seq_item_port.get_next_item(req);
	drive(phase);
	seq_item_port.item_done();
	end
	endtask : run_phase
	task drive(uvm_phase phase);
	phase.raise_objection(this);
	#5;
	`uvm_info(get_name(), $sformatf("in drive method req:\n%s", req.convert2string()), UVM_LOW)
	// Objection is not dropped
	//phase.drop_objection(this);
	endtask : drive
	endclass : my_driver
	class my_agent extends uvm_agent;
	my_seqr seqr;
	my_driver drv;
	`uvm_component_utils(my_agent)
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	seqr = my_seqr :: type_id :: create ("seqr", this);
	drv = my_driver :: type_id :: create ("drv", this);
	endfunction : build_phase
	function void connect_phase (uvm_phase phase);
	super.connect_phase(phase);
	drv.seq_item_port.connect(seqr.seq_item_export);
	endfunction : connect_phase
	endclass : my_agent
	class my_test extends uvm_test;
	my_agent agent;
	`uvm_component_utils(my_test)
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	agent = my_agent :: type_id :: create ("agent", this);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	my_seq seq;
	seq = my_seq :: type_id :: create("seq");
	phase.raise_objection(this);
	seq.start(agent.seqr);
	phase.drop_objection(this);
	endtask : run_phase
	endclass : my_test
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule : top
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO no_objection_drop.sv(67) @ 5: uvm_test_top.agent.drv [drv] in drive method req:
	// addr:0x82, data:0x5455120d
	// UVM_FATAL /opt/uvm-1.2/src/base/uvm_phase.svh(1489) @ 9200000000000: reporter [PH_TIMEOUT] Default timeout of 9200000000000 hit, indicating a probable testbench issue

view raw no_objection_drop.sv hosted with ❤ by GitHub

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Now let’s take another scenario,

Here driver is dropping objection after #105 timeunit. So simulation will move to next phase after #105. But the requirement is to move to next phase which is extract_phase after #50.

Let’s go through example.

-------------------------------------------------------------------------

	class my_seq_item extends uvm_sequence_item;
	rand bit [31:0] data;
	rand bit [7:0] addr;
	`uvm_object_utils_begin(my_seq_item)
	`uvm_field_int(addr, UVM_DEFAULT | UVM_HEX)
	`uvm_field_int(data, UVM_DEFAULT | UVM_HEX)
	`uvm_object_utils_end
	function new (string name = "my_seq_item");
	super.new(name);
	endfunction : new
	function string convert2string();
	convert2string = $sformatf("addr:0x%h, data:0x%h", addr, data);
	return convert2string;
	endfunction : convert2string
	endclass : my_seq_item
	class my_seq extends uvm_sequence#(my_seq_item);
	`uvm_object_utils(my_seq)
	function new (string name = "my_seq");
	super.new(name);
	endfunction : new
	task body();
	`uvm_create(req)
	start_item(req);
	if (!req.randomize()) begin
	`uvm_fatal(get_name(), $sformatf("Randomization of %s failed", req.get_type_name()))
	end
	finish_item(req);
	endtask : body
	endclass : my_seq
	class my_seqr extends uvm_sequencer#(my_seq_item);
	`uvm_component_utils(my_seqr)
	function new (string name = "my_seqr", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	endclass : my_seqr
	class my_driver extends uvm_driver#(my_seq_item);
	`uvm_component_utils(my_driver)
	function new (string name = "my_driver", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	forever begin
	seq_item_port.get_next_item(req);
	drive(phase);
	seq_item_port.item_done();
	end
	endtask : run_phase
	task drive(uvm_phase phase);
	phase.raise_objection(this);
	#5;
	`uvm_info(get_name(), $sformatf("in drive method req:\n%s", req.convert2string()), UVM_LOW)
	//Dropping objection from driver after #105 timeunit
	fork
	begin
	#100;
	`uvm_info(get_name(), $sformatf("in drive, dropping objection"), UVM_LOW)
	phase.drop_objection(this);
	end
	join_none
	endtask : drive
	endclass : my_driver
	class my_agent extends uvm_agent;
	my_seqr seqr;
	my_driver drv;
	`uvm_component_utils(my_agent)
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	seqr = my_seqr :: type_id :: create ("seqr", this);
	drv = my_driver :: type_id :: create ("drv", this);
	endfunction : build_phase
	function void connect_phase (uvm_phase phase);
	super.connect_phase(phase);
	drv.seq_item_port.connect(seqr.seq_item_export);
	endfunction : connect_phase
	endclass : my_agent
	class my_test extends uvm_test;
	my_agent agent;
	`uvm_component_utils(my_test)
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	agent = my_agent :: type_id :: create ("agent", this);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	my_seq seq;
	fork
	begin
	#50; //Timer
	// After #50 timeunit wants to move to next phase (extract_phase)
	end
	join_none
	seq = my_seq :: type_id :: create("seq");
	phase.raise_objection(this);
	seq.start(agent.seqr);
	phase.drop_objection(this);
	endtask : run_phase
	function void extract_phase(uvm_phase phase);
	// Expecting to execute at timeunit #50, but executing at #105
	`uvm_info(get_name(), $sformatf("Executing extract_phase"), UVM_LOW)
	endfunction : extract_phase
	endclass : my_test
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule : top
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO objection_dropped_after_timeout.sv(67) @ 5: uvm_test_top.agent.drv [drv] in drive method req:
	// addr:0x82, data:0x5455120d
	// UVM_INFO objection_dropped_after_timeout.sv(73) @ 105: uvm_test_top.agent.drv [drv] in drive, dropping objection
	// UVM_INFO /opt/uvm-1.2/src/base/uvm_objection.svh(1270) @ 105: reporter [TEST_DONE] 'run' phase is ready to proceed to the 'extract' phase
	// UVM_INFO objection_dropped_after_timeout.sv(132) @ 105: uvm_test_top [uvm_test_top] Executing extract_phase

view raw objection_dropped_after_timeout.sv hosted with ❤ by GitHub

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To fulfill the requirement we need to any how drop the pending objection after #50 to move to next phase after #50.

We can do this by getting list of all uvm_components (through get_objector method of uvm_objection class) who raised objection and then we can manually drop the objection after #50 timeunit.

Let’s go through example.

-------------------------------------------------------------------------

	class my_seq_item extends uvm_sequence_item;
	rand bit [31:0] data;
	rand bit [7:0] addr;
	`uvm_object_utils_begin(my_seq_item)
	`uvm_field_int(addr, UVM_DEFAULT | UVM_HEX)
	`uvm_field_int(data, UVM_DEFAULT | UVM_HEX)
	`uvm_object_utils_end
	function new (string name = "my_seq_item");
	super.new(name);
	endfunction : new
	function string convert2string();
	convert2string = $sformatf("addr:0x%h, data:0x%h", addr, data);
	return convert2string;
	endfunction : convert2string
	endclass : my_seq_item
	class my_seq extends uvm_sequence#(my_seq_item);
	`uvm_object_utils(my_seq)
	function new (string name = "my_seq");
	super.new(name);
	endfunction : new
	task body();
	`uvm_create(req)
	start_item(req);
	if (!req.randomize()) begin
	`uvm_fatal(get_name(), $sformatf("Randomization of %s failed", req.get_type_name()))
	end
	finish_item(req);
	endtask : body
	endclass : my_seq
	class my_seqr extends uvm_sequencer#(my_seq_item);
	`uvm_component_utils(my_seqr)
	function new (string name = "my_seqr", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	endclass : my_seqr
	class my_driver extends uvm_driver#(my_seq_item);
	`uvm_component_utils(my_driver)
	function new (string name = "my_driver", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	forever begin
	seq_item_port.get_next_item(req);
	drive(phase);
	seq_item_port.item_done();
	end
	endtask : run_phase
	task drive(uvm_phase phase);
	phase.raise_objection(this);
	#5;
	`uvm_info(get_name(), $sformatf("in drive method req:\n%s", req.convert2string()), UVM_LOW)
	// Objection is not dropped
	//phase.drop_objection(this);
	endtask : drive
	endclass : my_driver
	class my_agent extends uvm_agent;
	my_seqr seqr;
	my_driver drv;
	`uvm_component_utils(my_agent)
	function new (string name = "my_agent", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	seqr = my_seqr :: type_id :: create ("seqr", this);
	drv = my_driver :: type_id :: create ("drv", this);
	endfunction : build_phase
	function void connect_phase (uvm_phase phase);
	super.connect_phase(phase);
	drv.seq_item_port.connect(seqr.seq_item_export);
	endfunction : connect_phase
	endclass : my_agent
	class my_test extends uvm_test;
	my_agent agent;
	`uvm_component_utils(my_test)
	function new (string name = "my_test", uvm_component parent = null);
	super.new(name, parent);
	endfunction : new
	function void build_phase(uvm_phase phase);
	super.build_phase(phase);
	agent = my_agent :: type_id :: create ("agent", this);
	endfunction : build_phase
	task run_phase(uvm_phase phase);
	my_seq seq;
	fork
	begin
	#50; //Timer
	drop_all_objection(phase);
	end
	join_none
	seq = my_seq :: type_id :: create("seq");
	phase.raise_objection(this);
	seq.start(agent.seqr);
	phase.drop_objection(this);
	endtask : run_phase
	function void drop_all_objection(uvm_phase phase);
	uvm_objection objection;
	uvm_object object_q[$];
	// Get objection handle for current phase
	objection = phase.get_objection();
	// Get list of the uvm_components which doesn't drop the objection
	objection.get_objectors(object_q);
	// Dropping all the objection from all the objectors
	foreach(object_q[i]) begin
	while (objection.get_objection_count(object_q[i]) > 0) begin
	`uvm_info(get_type_name(),$sformatf("Dropping objection:%0d for object:%s", i, object_q[i].get_full_name()), UVM_LOW)
	objection.drop_objection(object_q[i]);
	end
	end
	endfunction : drop_all_objection
	endclass : my_test
	module top();
	initial begin
	run_test("my_test");
	end
	endmodule : top
	//Output:
	// UVM_INFO @ 0: reporter [RNTST] Running test my_test...
	// UVM_INFO drop_all_objection.sv(67) @ 5: uvm_test_top.agent.drv [drv] in drive method req:
	// addr:0x82, data:0x5455120d
	// UVM_INFO drop_all_objection.sv(137) @ 50: uvm_test_top [my_test] Dropping objection:1 for object:uvm_test_top.agent.drv
	// UVM_INFO /opt/uvm-1.2/src/base/uvm_objection.svh(1270) @ 50: reporter [TEST_DONE] 'run' phase is ready to proceed to the 'extract' phase

view raw drop_all_objection.sv hosted with ❤ by GitHub

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Reference:

1) uvm_objection.svh file