Missing header file

Hello...

I am trying to build from source on a BeagleBone Black.  The configure process was successful.  But the make step is not sucessful.

After some time, I receive the following error:
rtapi/rtapi_io.h:39:12: fatal error: sys/io.h: No such file or directory

I can't find an io.h ...does anyone know where this should be?  The compiler directives in rtapi_io.h are looking for MODULE

#ifndef RTAPI_IO_H
#define RTAPI_IO_H

#define RTAPI_IO        // for disabling parts of header files

#include "config.h"        // build configuration
#include "rtapi.h"        // these functions

#ifdef MODULE
#  if LINUX_VERSION_CODE > KERNEL_VERSION(2,4,17)
#    include <asm/io.h>        /* inb(), outb() */
#  else
#    include <sys/io.h>        /* inb(), outb() */
#  endif
#else
#  include <sys/io.h>        /* inb(), outb() */
#endif


#ifdef RTAPI_IO

Does anyone have any experience with this issue?

Thanks,  Alan