calling $dumpvars() from a task

Question

Is there a way to call $dumpvars, $dumpon $dumpoff from the body() of a sequence ? It is possible from a module task. I need to control $dumpon $dumpoff so that the dump won't be too large An alternative way would be to turn on a bit top.dump_on in the sequence and wait on this bit in the testbench

EDIT:

I added a top level module :

  module dump ();

   bit stop=1'b0;

   task do_dump(string id);

     fork begin
        $display("DUMP START %s", id);
        $dumpfile($psprintf("dump_%s.vcd", id));  
        $dumpvars(1, hmr_top.i_hmr.REF_CLK_IN, 
                     hmr_top.i_hmr.RST_N, 
                     hmr_top.i_hmr.SER_CLK, 
                     hmr_top.i_hmr.VMKMODE, 
                     hmr_top.i_hmr.SERIN, 
                     hmr_top.i_hmr.SEROUT, 
                     hmr_top.i_hmr.REF_CLK_OUT);
        $dumpon;
        wait(stop);
        stop = 1'b0;
        $dumpoff;
        $display("DUMP END %s", id);
     end join_none
   endtask

  function stop_dump();
      stop = 1'b1;
  endfunction

endmodule // dump

But when I try to invoke a second dump I get this Error :

Warning-[TFX-DUMPVARCA] DumpVar called previously   As $dumpvars was called in previous time step, ignoring this call.$dumpfile    at time
#11551000   Please refer to section 18.1.2 in the IEEE Verilog Standard 1364-2001 for    details on $dumpvars.

any ideas ? Thx

Answer 1

Yes, you can call these system tasks from the body task in a UVM sequence. However, if the body task is called more than once in a simulation, you may get warnings for $dumpvar. According to the IEEE Std 1800-2012, Section 21.7.1.2 "Specifying variables to be dumped ($dumpvars)":

The $dumpvars task can be invoked as often as desired throughout the model (for example, within various blocks), but the execution of all the $dumpvars tasks shall be at the same simulation time.

Answer 2

You can certainly call $dumpon or $dumpoff from the body of a sequence, but if the sequence is defined in a package (as it should be), you will not be able to specify a specific hierarchical pathname to dump.