Thanks for your help & support!!
I've made this , and I have just one more problem that is:
I've made a new ser-sim.c file, actually It seems like ser-pipe.c but with
empty functions for open/close and a _initialize.... function which is a copy
from _initialize_ser_pipe() but that use the new empty sim_open() and
sim_close.
I've made the gdb to obtain a ser-sim.o file.
I've changed the configure.in file to add this file where the other ser-**
are. I ran configure , and I've obtained no ser-sim.o entry in the Makefile,
where the other ser-*.o are. Not yet in init.c.
But, when I've changed manually Makefile and added the ser-sim.o file where
the other files are, I've got the desired init.c file , with the
_initialize_ser_sim() function in its code.
What should I do to make this clean from configure??