dkio(4) 						     Kernel Interfaces Manual							   dkio(4)

Name
       dkio - 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 partitions, a or c.

		       If  the a or c partition is not mounted, only the partition table in the driver is modified.  This temporarily modifies the
		       partition table of the disk.  The modifications 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  primary
		       superblock are modified.  This permanently modifies the partition table of the disk.  This is not recommended.  To change a
		       partition table permanently, use the command.

       DIOCDGTPT       Indicates to the driver to store the default information 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 structdevget.

       DKIOCACC        This code is defined in It is currently unused.

Restrictions
       These restrictions apply when using the DIOCSETPT ioctl code:

       o   You must have superuser privileges.

       o   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.

       o   You cannot change the offset of the a partition.

Examples
       This example shows how to use the DIOGETPT ioctl code to print the length and offset of the a partition of an RZ23 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/rz0a",0)) < 0 ) {
		 printf("Unable to open device
");
		 exit(2);
	    }

	    /* Get the partition information */

	    if ( ioctl(fd,DIOCGETPT,&arg) < 0 )
		 printf("Error in ioctl
");

	    printf("Length		Offset
");

	    for ( i = 0; i <= 7; i++ ) {
		 printf("%d		%d
",arg.pt_part[i].pi_nblocks,
			     arg.pt_part[i].pi_blkoff );
	    }
       }

Files
See Also
       rz(4), disktab(5), fstab(5), chpt(8), diskpart(8), fsck(8), MAKEDEV(8), mkfs(8), tunefs(8)

								       RISC								   dkio(4)