dkio(4)dkio(4)Namedkio - disk interface
Syntax
#include <sys/fs.h>
#include <sys/ioctl.h>
Description
This section describes the ioctl (input/output controller) codes for
all disk drivers. The basic ioctl (input/output controller) format is:
#include <sys/fs.h>
#include <sys/ioctl.h>
ioctl(fildes, code, arg)
struct pt *arg;
The applicable codes are:
DIOCGETPT Indicates to the driver to store the information in the
current partition table in the address pointed to by
arg. The file descriptor must be opened on the raw
partitions, a or c.
DIOCGETPT does not change the partition table, but it
does provide access to the partition table information.
DIOCSETPT Indicates to the driver to modify the current partition
table with the information pointed to by arg.
The file descriptor must be opened on the raw parti‐
tions, a or c.
If the a or c partition is not mounted, only the parti‐
tion table in the driver is modified. This temporarily
modifies the partition table of the disk. The modifi‐
cations are overwritten with the default table when the
disk is turned off and on.
If the a or c partition is mounted, both the partition
table in the driver and the partition table in the pri‐
mary superblock are modified. This permanently modi‐
fies the partition table of the disk. This is not rec‐
ommended. To change a partition table permanently, use
the command.
DIOCDGTPT Indicates to the driver to store the default informa‐
tion of the current partition table in the address
pointed to by arg. The file descriptor must be opened
on the raw partitions, a or c.
DIOCGETPT does not change the partition table, but it
does provide access to the partition table information.
DKIOCGET Allows the user to receive generic disk information as
defined in struct devget.
DKIOCACC This code is defined in For an MSCP class disk, the
driver performs one of the following functions:
ACC_REVEC Forces revector of a specified disk block.
ACC_SCAN Scans an area of the disk reporting any
forced errors found and revectoring any
bad blocks found.
DKIOCEXCL This command is used to set and clear the exclusive
access attribute on controllers that provide multihost
support. In this case arg is an integer pointer. If
the value of arg is 0 the exclusive access attribute
will be cleared. If the value of arg is nonzero the
exclusive access attribute will be set. The exclusive
access attribute is set on a per-drive basis and can
not be used selectively on individual partitions.
Attempts to clear the exclusive attribute will fail if
the drive is not currently set exclusive access to the
issuing host or the underlying controller or driver
does not support multihost exclusive access. Attempts
to set the exclusive attribute will fail if the drive
is already exclusively associated with another host or
the underlying controller or driver does not support
multihost exclusive access.
Examples
This example shows how to use the DIOGETPT ioctl code to print the
length and offset of the a partition of an RA81 disk:
#include <sys/types.h>
#include <sys/param.h>
#include <sys/fs.h>
#include <sys/ioctl.h>
main()
{
struct pt arg;
int fd, i;
/* Open the "a" partition of the disk you want to see */
if ( (fd = open("/dev/rra0a",0)) < 0 ) {
printf("Unable to open device\n");
exit(2);
}
/* Get the partition information */
if ( ioctl(fd,DIOCGETPT,&arg) < 0 )
printf("Error in ioctl\n");
printf("Length\t\tOffset\n");
for ( i = 0; i <= 7; i++ ) {
printf("%d\t\t%d\n",arg.pt_part[i].pi_nblocks,
arg.pt_part[i].pi_blkoff );
}
}
Restrictions
These restrictions apply when using the DIOCSETPT ioctl code:
· You must have superuser privileges.
· You cannot shrink or change the offset of a partition with a file
system mounted on it or with an open file descriptor on the entire
partition.
· You cannot change the offset of the a partition.
· The exclusive access ioctl DKIOCEXCL is only supported on HSC ver‐
sion V5.00 or later.
FilesSee Alsohp(4), ra(4), rb(4), rd(4), rk(4), rl(4), rx(4), disktab(5), fstab(5),
chpt(8), diskpart(8), fsck(8), MAKEDEV(8), mkfs(8), tunefs(8)
VAX dkio(4)
