%Warning-DEFPARAM: t/t_lint_defparam.v:9: Suggest replace defparam assignment with Verilog 2001 #(.P(...etc...))
   defparam sub.P = 2;
                  ^
                   ... Use "/* verilator lint_off DEFPARAM */" and lint_on around source to disable this message.
%Error: Exiting due to
