Abruptly killing a sequence results in UVM_ERROR

[sounderkumar]

In the body of a virtual sequence I have a sequence running inside fork join, which is then killed by disabling the thread, like so:

 

virtual task body();

....    

    fork:seq_thread

        `uvm_do_on(my_seq, my_seqr)

    join

    @(negedge reset_b );

    disable seq_thread;

...

...

endtask;

 

 

On doing this, we get the following error from the sequencer:

 

[sEQREQZMB] The task responsible for requesting a wait_for_grant on sequencer 'uvm_test_top.env.my_seqr' for sequence 'uvm_test_top.env.soc_v_sequencer.my_vseq.my_seq' has been killed, to avoid a deadlock the sequence will be removed from the arbitration queues.

 

What can I do in my virtual sequence to cleanly kill 'my_seq' when reset_b is asserted ? 

 

[tudor.timi]

There's a stop_sequences() method in uvm_sequencer that you can use. Just call that after the disable. If you need finer control (just stopping one sequence because you have other running in parallel that has to still run) you can call seq.kill() after the disable.

[uwes]

hi,

 

"cold" killing a sequence by terminating the thread via fork/join/disable or process::kill very likely hangs the sequence-sequencer-driver interaction and a couple of handshakes. In the good case all you get is a message like the one you show. in the bad case it will render the sequencer in-operational. If you really need to terminate a sequence from the outside then .stop_sequences() and seq.kill(). But also keep in mind that one eventually has to perform add actions like resetting registers semaphores, resetting the driver etc otherwise you did just a reset of one part of your env and the rest is still in flight (for instance if you terminate a sequence which currently executes an item on the driver you need todo something with the driver otherwise the sequencer-driver handshake is out of sync.

 

 

/uwe