Hi, Suppose I started a sequence on a sequencer in a test. And, if specific condition is met, the sequence kills itself. But when I try to start the sequence on the sequencer again, I get SEQ_NOT_DONE error. UVM_FATAL @ 0: uvm_test_top.env.agent.sequencer@@seq [SEQ_NOT_DONE] Sequence uvm_test_to…

In reply to Jung Ik Moon : I guess the way it codes indicates that killed() is never supposed to be called by sequence itself. If you wanna terminate sequence inside body() there’re many other ways also.

In reply to Jung Ik Moon : [image] EDA Playground Edit, save, simulate, synthesize SystemVerilog, Verilog, VHDL and other HDLs from your web browser.

In reply to Jung Ik Moon : You are trying to start the same sequence twice at the same time. This does not work. See the error message (fatal): UVM_FATAL @ 0: uvm_test_top.env.agent.sequencer@@seq [SEQ_NOT_DONE] Sequence uvm_test_top.env.agent.sequencer.seq already started

In reply to chr_sue : Thanks for the answer. But, as far as I understand, it’s okay to start the same sequence twice (sequentially) as long as its state is CREATED, STOPPED or FINISHED. For example, if I comment out ‘this.kill();’ from my example sequence, there will be no error. And that covers b…

In reply to Jung Ik Moon : This is very easy. Because calling the start method in the test is not blocking. The 2nd call does not wait until the first has been executed.

In reply to chr_sue : Not sure if that’s true. The 2nd call will not be executed until the 1st one is either finished or killed.

In reply to Jung Ik Moon : You are right. see here: [image] EDA Playground Edit, save, simulate, synthesize SystemVerilog, Verilog, VHDL and other HDLs from your web browser. But note the kill is in the test and not in the body task of your sequence.

In reply to chr_sue : Your example kills already finished sequence. Yeah, that’s not the important thing here. I understand what you were trying to say. I can kill the sequence in the test rather than in the sequence. I can also achieve the same by calling stop_sequences() of the sequencer. In …

In reply to Jung Ik Moon : if you dig a little bit deeper into source code you will see why. m_sequence_process is the process forked once you enter body() task. this.kill() will call m_kill() which will set m_sequence_state = UVM_STOPPED, and then you could restart your sequence again ideally. b…

In reply to Jeff_Li_90 : Thanks for the answer. I actually did get to the point where you mentioned. But I could not understand “why”. Maybe I should change my question this way: “Why doesn’t UVM guarantee that the sequence state change to STOPPED when the sequence kills itself? Or is this inte…

In reply to Jeff_Li_90 : Hmm… I see. Seems like sequence killing itself is not an intended way of using UVM. Thanks.

State of the sequence after it has been killed

UVM

Jung_Ik_Moon February 21, 2022, 8:13am 2

In reply to Jung Ik Moon: