dump FSDB波形

在使用脚本dump FSDB波形的时候，遇到以下问题：

脚本如下：
initial begin
$fsdbDumpfile("./cosim.fsdb");
$fsdbDumpvars(0, top);
$fsdbDumpon;
#Length
$fsdbDumpoff;
$display("cosim success");
$finish;
end

运行脚本后遇到编译器报出以下ERROR：

$fsdbDumpfile("./cosim.fsdb");
ncsim: *E,MSSYSTF (./top_cosim.src,41|16): User Defined system task or function registered during elaboration and used within the simulation has not been registered during simulation.
$fsdbDumpvars(0, top);
ncsim: *E,MSSYSTF (./top_cosim.src,42|16): User Defined system task or function registered during elaboration and used within the simulation has not been registered during simulation.
$fsdbDumpon;
ncsim: *E,MSSYSTF (./top_cosim.src,43|14): User Defined system task or function registered during elaboration and used within the simulation has not been registered during simulation.
$fsdbDumpoff;
ncsim: *E,MSSYSTF (./top_cosim.src,45|15): User Defined system task or function registered during elaboration and used within the simulation has not been registered during simulation.

原因是没有正确Link PLI

解决办法：

1.在cshell中vcs工具的环境变量中设置：

      setenv LD_LIBRARY_PATH $Novas_HOME/share/PLI/ius8.2_vhpi/Linux/boot

2.在脚本中添加以下语句：

      ncverilog +loadpli1=/tools/synopsys/Verdi-xxx/share/PLI/IUS/LINUX64/boot/debpli.so:debpli_boot  （亲测可用）

      ncverilog -loadpli1 debpli:novas_pli_boot +access+rw -f run.f （没有尝试过）