using always@* | meaning and drawbacks

Question

can you say what is the meaning of that

• always @ *

Is there any possible side effects after using that statement ?

Answer 1

It's just a shortcut for listing all of the wires that the always block depends on. Those wires are the "sensitivity list". One advantage of using it is that synthesized code is unlikely to care what you put in the sensitivity list (other than posedge and negedge) because the wires will be "physically" connected together. A simulator might rely on the list to choose which events should cause the block to execute. If you change the block and forget to update the list your simulation might diverge from the actual synthesized behavior.