In reply to verif_learner:
uvm_config_db::get() will get the value for field_name in inst_name, using component cntxt as the starting search point.
In the example below， cnxt is this and inst_name is empty “”， this keyword refers to the component’s current instance. so get（）will loop up fld_name setting by using the component’s current instance as the starting point. If fld_name setting is found, get its setting to my_val.
uvm_config_db#(int)::get(this,"","fld_name", my_val);
In the example below, get() will search fld_name setting by using top.module_a.instance_a as the starting point.
uvm_config_db#(int)::get("top",".module_a.instance_a","fld_name", my_val);