struct cb_ops  {
		int		*cb_open)(dev_t *devp, int flag, int otyp, 
						cred_t *credp);
		int		(*cb_close)(dev_t dev, int flag, int otyp, 
						cred_t *credp);
		int		(*cb_strategy)(struct buf *bp);
		int		(*cb_print)(dev_t dev, char *str);
		int		(*cb_dump)(dev_t dev, caddr_t addr,daddr_t blkno, 
						int nblk);
		int		(*cb_read)(dev_t dev, struct uio *uiop, cred_t *credp);
		int		(*cb_write)(dev_t dev, struct uio *uiop, cred_t *credp);
		int		(*cb_ioctl)(dev_t dev, int cmd, int arg, int mode,
						cred_t *credp, int *rvalp);
		int		(*cb_devmap)(dev_t dev, dev_info_t *dip, 
						ddi_devmap_data_t *dvdp, ddi_devmap_cmd_t cmd, 
						off_t offset, unsigned int len, unsigned int prot, 
						cred_t *credp);
		int		(*cb_mmap)(dev_t dev, off_t off, int prot);
		int		(*cb_segmap)(dev_t dev, off_t off, struct as *asp, 
						caddr_t *addrp, off_t len, unsigned int prot, 
						unsigned int maxprot, unsigned int flags, 
						cred_t *credp);
		int		(*cb_chpoll)(dev_t dev, short events, int anyyet, 
						short *reventsp, struct pollhead **phpp);
		int		(*cb_prop_op)(dev_t dev, dev_info_t *dip, 
						ddi_prop_op_t prop_op, int mod_flags, char *name, 
						caddr_t valuep, int *length);

     struct streamtab *cb_str;		/* streams information */

		/*
		 * The cb_flag fields are here to tell the system a bit about 
		 * the device. The bit definitions are in <sys/conf.h>.
		 */
     int		cb_flag;					/* driver compatibility flag */
};