NBI is due for removal

src/arch/i386/image/nbi.c

 #include "etherboot.h"
 #include "errno.h"
 
+#warning "This file is obsolete"
+#if 0
+
 /** @file
  *
  * NBI image format.
 	.load	= nbi_load,
 	.boot	= nbi_boot,
 };
+
+#endif