2010.01.02
It works! Boot system called Syscall-240. And I only had to do
  make depend
  make
  make bzImage

Replace the unused futex system call number 240 with my_syscall. I'll still
use the __NR_futex reference number, but replace the sys_ni_syscall with
my_syscall in entry.S.

The following modifications are needed to add the simplest system call with no 
parameters and no return value.

<asm/unistd.h>          No change needed, just use the __NR_futex number.
/usr/src/linux/arch/i386/kernel/entry.S    Replace call 240 with my_syscall 

Edit the Makefile to add a reference to the object file with the my_syscall
code definition in this directory. I did this in CORE_FILES

2010.01.02
This Nutt lab 5 is about adding system calls and requires re-compiling the
kernel.