ultrix man page for devio

devio(4)						     Kernel Interfaces Manual							  devio(4)

Name
       devio - device information interface

Syntax
       #include <sys/ioctl.h>
       #include <sys/devio.h>

Description
       The  interface  obtains	status,  device  attributes,  and other information by polling the controlling device driver.  There are two ioctl
       requests associated with this interface: DEVIOCGET and DEVGETGEOM.

       The file contains the needed structure and definitions to use the DEVIOCGET and DEVGETGEOM ioctl requests.

       The DEVIOCGET ioctl request is used to obtain generic device information by polling the underlying device driver.   The	following  example
       shows the basic structure used by this request:
       /* Structure for DEVIOCGET ioctl - device get status command */

       struct devget  {
	  short   category;	       /* Category		     */
	  short   bus;		       /* Bus			     */
	  char	  interface[DEV_SIZE]; /* Interface (string)	     */
	  char	  device[DEV_SIZE];    /* Device (string)	     */
	  short   adpt_num;	       /* Adapter number	     */
	  short   nexus_num;	       /* Nexus or node on adapter # */
	  short   bus_num;	       /* Bus number		     */
	  short   ctlr_num;	       /* Controller number	     */
	  short   slave_num;	       /* Plug or line number	     */
	  char	  dev_name[DEV_SIZE];  /* ULTRIX device mnemonic     */
	  short   unit_num;	       /* ULTRIX device unit number  */
	  unsigned soft_count;	       /* Driver soft error count    */
	  unsigned hard_count;	       /* Driver hard error count    */
	  long	  stat; 	       /* Generic status mask	     */
	  long	  category_stat;       /* Category specific mask     */
       };

       The DEVGETGEOM ioctl request is used to obtain disk geometry and attributes by polling the underlying device driver.  This ioctl request is
       only supported on MSCP and SCSI disk drivers.  The ioctl fails on other types of drivers which do not support DEVGETGEOM.   The	ioctl  may
       fail if the device driver is unable to obtain geometry information.  This could happen if the disk media is removable and there is no media
       loaded in the drive.

       The following example shows the basic structure used by this request:
       /* Structure for DEVGETGEOM ioctl - disk geometry information */

       typedef union devgeom {
	 struct {
	    unsigned long  dev_size;   /* number of blocks in user area  */
	    unsigned short  ntracks;   /* number of tracks per cylinder  */
	    unsigned short  nsectors;  /* number of sectors per track	 */
	    unsigned short  ncylinders; /* total number of cylinders	 */
	    unsigned long   attributes; /* Device attributes		 */
	  } geom_info;
	  unsigned char       pad[124];  /* Allocate space for expansion */
       } DEVGEOMST;
       The following is a description of the fields of the DEVGEOMST data structure.  Many of the fields correspond to attributes that	are  often
       specified in the disk description file This ioctl is used by the subroutine to dynamically generate disktab entries.

       dev_size    This  field	contains the number of user accessible blocks on the disk.  The corresponding disktab field is which describes the
		   size of the "c" partition.

       ntracks	   This field contains the number of tracks per cylinder and corresponds to the field of a disktab entry.

       nsectors    This field contains the number of sectors per track and corresponds to the field of a disktab entry.

       ncylinders  This field contains the number of cylinders on the disk and corresponds to the field of a disktab entry.

       attributes  This field represents disk attributes.

       pad	   This field is not used to store disk information.  The pad element of the DEVGEOMST is used to provide room for  future  expan-
		   sion of the information fields.

Restrictions
       The DEVGETGEOM ioctl request is only supported on MSCP and SCSI disk drivers.

See Also
       creatediskbyname(3x), ra(4), rz(4), disktab(5)

																	  devio(4)