Adding a dummy system call

Hi Everyone, I am trying to learn the linux kernel via the book Linux Kernel Development 3rd edition by Robert Love, and in it he advises to use the macro _syscallX to allow access to user added syscalls not wrapped by glibc functions. In my attempt to add a system call this macro failed me and after a little man page perusal I noticed _syscallX is obselete. Is it considered a better practice to declare the asmlinkage int sys_X(..) declaration myself instead of using this obsolete macro? Or did syscall(2) replace it? And if it was replaced does anyone have a reference they could point me for adding system calls in kernel 3.10 or similar? thank you in advance!