devio - device information interface
#include <sys/ioctl.h> #include <sys/devgetinfo.h>
#include <sys/devio.h>
The devio interface obtains status, device attributes, and
other information by polling the controlling device
driver. There are three ioctl requests associated with
this interface: DEVIOCGET, DEVGETINFO and DEVGETGEOM.
The file <sys/devgetinfo.h> contains the structures and
definitions needed by the DEVGETINFO ioctl request; the
file <sys/devio.h> contains the structures and definitions
needed by the DEVIOCGET and DEVGETGEOM ioctl requests.
The DEVGETINFO and DEVIOCGET ioctl requests are used to
obtain generic device information by polling the underlying
device driver. DEVGETINFO is used by disk and tape
device drivers; DEVIOCGET is used by other kernel subsystems.
For DEVIOCGET, the devget structure is the basic structured
used by this request. The devget structure has the
following definition:
/* 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 rctlr_num; /* Remote controller number
*/
short slave_num; /* Plug or line number
*/
char dev_name[DEV_SIZE]; /* Device mnemonic
*/
short unit_num; /* 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
*/ };
For DEVGETINFO, the device_info_t union is the top-level
definition of the information returned to the
device_info_t union is the top-level definition of the
information returned to the DEVGETINFO ioctl request. It
has the following definition:
typedef union device_info {
int version; /* version number */
v1_device_info_t v1; /* bus and device information */
uchar_t pad[1024]; /* unused */
} device_info_t;
The v1_device_info_t structure contains all the information
returned to the user data buffer by the DEVGETINFO
ioctl command. This structure is contained within the
device_info_t structure so that the same interface can be
used for various versions of the data structure. It has
the following definition:
typedef struct v1_device_info {
int version; /* version number
*/
short category; /* device type, i.e.,
disk */
short bus; /* bus type
*/
char interface[DEV_STRING_SIZE]; /* interface type,
i.e., HSC40 */
char device[DEV_STRING_SIZE]; /* device description
*/
char dev_name[DEV_STRING_SIZE]; /* device name
*/
ulong_t soft_count; /* number of soft
errors */
ulong_t hard_count; /* number of hard
errors */
v1_devtype_info_t devinfo; /* device-type information
*/
v1_bustype_info_t businfo; /* bus-type information
*/
uchar_t private[DEV_PRIVATE_LEN]; /* driver-specific
*/ } v1_device_info_t;
The v1_bustype_info_t structure returns information about
the bus type. It has the following definition:
typedef struct v1_bustype_info {
int adpt_num; /* controller chip relative to current
adaptor */
int nexus_num; /* slot that the adaptor is using
*/
int bus_num; /* logical bus number for the adaptor
*/
int ctlr_num; /* system-wide instance number of the
adaptor */
int rctlr_num; /* remote ID for the adaptor
*/
int slave_num; /* number of the device relative to the
controlling hardware
*/
int unit_num; /* system-wide number of this device
*/
int pad0; /* unused
*/
union { v1_scsi_bus_info_t scsi; /* SCSI-specific
*/ uchar_t busdata[DEV_BUS_LEN];
/* bus-specific */
} bus; } v1_bustype_info_t;
The v1_devtype_info_t union returns device-specific information.
The contents of the v1_devtype_info_t union
depends on the device type, either disk, tape, or other
device type. The structure has the following definition:
typedef union v1_devtype_info{
v1_disk_dev_info_t disk; /* disk-specific status
*/
v1_tape_dev_info_t tape; /* tape-specific status
*/
v1_term_dev_info_t term; /* terminal-specific
status */
uchar_t devdata[DEV_TYPE_LEN]; /* other device-type
status */ } v1_devtype_info_t;
For disk devices, the v1_devtype_info_t union contains a
v1_disk_dev_info_t structure, defined as follows:
typedef struct v1_disk_dev_info {
ulong_t status; /* device status
*/
ulong_t capacity; /* number of blocks on the
device */
ulong_t blocksz; /* number of bytes per
block */
uchar_t class; /* disk class, such as
diskette */
uchar_t part_num; /* total number of partitions
*/
uchar_t raid_level /* RAID level of the device
*/
uchar_t pad0; /* unused
*/
ushort_t media_changes; /* number of media changes
(diskette) */
ushort_t pad1; /* unused
*/
union {
struct { uchar_t density_code; /* SCSI
density code */ uchar_t flags;
/* SCSI flags */
} scsi; uchar_t archdata[DEV_ARCH_LEN]; /*
architecture-specific */
} arch; } v1_disk_dev_info_t;
For tape devices, the v1_devtype_info_t union contains a
v1_tape_dev_info_t structure, defined as follows:
typedef struct v1_tape_dev_info {
uint_t media_status; /* current status of
the media */
uint_t unit_status; /* current status of
the unit */
long recordsz; /* record size, or 0
for
variable-sized
records */
long density_bpi; /* current density
setting */
long density_bpi_wrt; /* density used for
writes */
long position; /* number of records
written since
the last file mark
*/
long fm_cnt; /* number of file marks
since the
beginning of the
tape */
uchar_t class; /* tape device class
*/
uchar_t pad[7]; /* unused
*/
union {
struct { uint_t blocking_factor; /*
blocking factor */ uchar_t valid_flags;
/* valid flags */ uchar_t density_code;
/* density code */
uchar_t buffered_mode; /* buffered mode */
uchar_t speed; /* tape speed
*/ uchar_t compression_code; /* compression code
*/
} scsi; uchar_t archdata[DEV_ARCH_LEN]; /*
architecture-specific */
} arch; } v1_tape_dev_info_t;
The DEVGETGEOM ioctl request is used to obtain disk geometry
and attributes by polling the underlying device
driver. The ioctl fails on other types of drivers which do
not support DEVGETGEOM. The DEVGETGEOM may also 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:
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
*/
unsigned long sector_size; /* number of bytes per
sector */
unsigned long min_trans; /* minimum transer size
*/
unsigned long max_trans; /* maximum transfer size
*/
unsigned long prefer_trans; /* perferred transfer
size */
unsigned int headswitch; /* head switch time
*/
unsigned int trkseek; /* track-to-track seek
time */
unsigned int acylinders; /* alternate cylinders
per unit */
unsigned short rpm; /* rotational speed
*/
unsigned short interleave; /* hardware sector interleave
*/
unsigned short trackskew; /* sector 0 skew, per
track */
unsigned short sparespertrack; /* spare sectors per
track */
unsigned short sparespercyl; /* spare sectors per
cylinder */
unsigned short cylskew; /* sector 0 skew, per
cylinder */
} geom_info;
unsigned char pad[108]; /* 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 /etc/disktab . This ioctl is used by the creatediskbyname
subroutine to dynamically generate disktab
entries. This field contains the number of user accessible
blocks on the disk. The corresponding disktab field is
pc, which describes the size of the "c" partition. This
field contains the number of tracks per cylinder and corresponds
to the nt field of a disktab entry. This field
contains the number of sectors per track and corresponds
to the ns field of a disktab entry. This field contains
the number of cylinders on the disk and corresponds to the
nc field of a disktab entry. This field represents disk
attributes. This field specifies the number of bytes per
sector. This field specifies the minimum number of bytes
that can be transferred at one time. This field specifies
the maximum number of bytes that can be transferred at one
time. This field specifies the preferred number of bytes
in any single transfer. This field specifies the number
of microseconds the disk takes to switch heads. This
field specifies the number of microseconds the disk takes
to seek from track to track. This field specifies the
number of alternate cylinders that exist on the unit.
This field specifies the rotational speed of the disk.
This field specifies the hardware sector interleave. This
field specifies the sector 0 skew, per track. This field
specifies the number of spare sectors that exist on each
track. This field specifies the number of spare sectors
that exist on each cynlinder. This field specifies the
sector 0 skew, per cylinder. This field is not used to
store disk information. The pad element of the DEVGEOMST
is used to provide room for future expansion of the information
fields.
disktab(4)
devio(7)
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