usr/src/sys/i386/include/dkio.h

/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)dkio.h      8.1 (Berkeley) %G%
 */

/*
 * Structures and definitions for disk io control commands
 *
 * THIS WHOLE AREA NEEDS MORE THOUGHT.  FOR NOW JUST IMPLEMENT
 * ENOUGH TO READ AND WRITE HEADERS ON MASSBUS DISKS.  EVENTUALLY
 * SHOULD BE ABLE TO DETERMINE DRIVE TYPE AND DO OTHER GOOD STUFF.
 */

/* disk io control commands */
#define DKIOCHDR        _IO(d, 1)       /* next I/O will read/write header */