385 lines
13 KiB
Groff
385 lines
13 KiB
Groff
.\" Copyright (c) 1987, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Symmetric Computer Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93
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.\"
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.Dd June 5, 1993
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.Dt DISKLABEL 5
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.Os
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.Sh NAME
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.Nm disklabel
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.Nd disk pack label
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.Sh SYNOPSIS
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.Fd #include <sys/disklabel.h>
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.Sh DESCRIPTION
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Each disk or disk pack on a system may contain a disk label
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which provides detailed information
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about the geometry of the disk and the partitions into which the disk
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is divided.
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It should be initialized when the disk is formatted,
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and may be changed later with the
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.Xr disklabel 8
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program.
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This information is used by the system disk driver and by the bootstrap
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program to determine how to program the drive
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and where to find the filesystems on the disk partitions.
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Additional information is used by the filesystem in order
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to use the disk most efficiently and to locate important filesystem information.
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The description of each partition contains an identifier for the partition
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type (standard filesystem, swap area, etc.).
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The filesystem updates the in-core copy of the label if it contains
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incomplete information about the filesystem.
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.Pp
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The label is located in sector number
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.Dv LABELSECTOR
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of the drive, usually sector 0 where it may be found
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without any information about the disk geometry.
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It is at an offset
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.Dv LABELOFFSET
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from the beginning of the sector, to allow room for the initial bootstrap.
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The disk sector containing the label is normally made read-only
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so that it is not accidentally overwritten by pack-to-pack copies
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or swap operations;
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the
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.Dv DIOCWLABEL
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.Xr ioctl 2 ,
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which is done as needed by the
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.Xr disklabel
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program.
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.Pp
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A copy of the in-core label for a disk can be obtained with the
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.Dv DIOCGDINFO
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.Xr ioctl ;
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this works with a file descriptor for a block or character (``raw'') device
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for any partition of the disk.
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The in-core copy of the label is set by the
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.Dv DIOCSDINFO
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.Xr ioctl .
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The offset of a partition cannot generally be changed while it is open,
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nor can it be made smaller while it is open.
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One exception is that any change is allowed if no label was found
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on the disk, and the driver was able to construct only a skeletal label
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without partition information.
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Finally, the
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.Dv DIOCWDINFO
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.Xr ioctl
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operation sets the in-core label and then updates the on-disk label;
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there must be an existing label on the disk for this operation to succeed.
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Thus, the initial label for a disk or disk pack must be installed
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by writing to the raw disk.
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All of these operations are normally done using
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.Xr disklabel .
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.Pp
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The format of the disk label, as specified in
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.Aw Pa sys/disklabel.h ,
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is
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.Bd -literal
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/*
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* Disk description table, see disktab(5)
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*/
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#define DISKTAB "/etc/disktab"
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/*
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* Each disk has a label which includes information about the hardware
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* disk geometry, filesystem partitions, and drive specific information.
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* The label is in block 0 or 1, possibly offset from the beginning
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* to leave room for a bootstrap, etc.
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*/
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#ifndef LABELSECTOR
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#define LABELSECTOR 0 /* sector containing label */
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#endif
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#ifndef LABELOFFSET
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#define LABELOFFSET 64 /* offset of label in sector */
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#endif
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#define DISKMAGIC ((u_long) 0x82564557) /* The disk magic number */
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#ifndef MAXPARTITIONS
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#define MAXPARTITIONS 8
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#endif
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#ifndef LOCORE
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struct disklabel {
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u_long d_magic; /* the magic number */
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short d_type; /* drive type */
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short d_subtype; /* controller/d_type specific */
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char d_typename[16]; /* type name, e.g. "eagle" */
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/*
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* d_packname contains the pack identifier and is returned when
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* the disklabel is read off the disk or in-core copy.
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* d_boot0 and d_boot1 are the (optional) names of the
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* primary (block 0) and secondary (block 1-15) bootstraps
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* as found in /usr/mdec. These are returned when using
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* getdiskbyname(3)
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to retrieve the values from /etc/disktab.
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*/
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#if defined(KERNEL) || defined(STANDALONE)
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char d_packname[16]; /* pack identifier */
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#else
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union {
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char un_d_packname[16]; /* pack identifier */
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struct {
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char *un_d_boot0; /* primary bootstrap name */
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char *un_d_boot1; /* secondary bootstrap name */
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} un_b;
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} d_un;
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#define d_packname d_un.un_d_packname
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#define d_boot0 d_un.un_b.un_d_boot0
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#define d_boot1 d_un.un_b.un_d_boot1
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#endif /* ! KERNEL or STANDALONE */
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/* disk geometry: */
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u_long d_secsize; /* # of bytes per sector */
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u_long d_nsectors; /* # of data sectors per track */
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u_long d_ntracks; /* # of tracks per cylinder */
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u_long d_ncylinders; /* # of data cylinders per unit */
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u_long d_secpercyl; /* # of data sectors per cylinder */
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u_long d_secperunit; /* # of data sectors per unit */
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/*
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* Spares (bad sector replacements) below
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* are not counted in d_nsectors or d_secpercyl.
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* Spare sectors are assumed to be physical sectors
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* which occupy space at the end of each track and/or cylinder.
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*/
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u_short d_sparespertrack; /* # of spare sectors per track */
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u_short d_sparespercyl; /* # of spare sectors per cylinder */
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/*
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* Alternate cylinders include maintenance, replacement,
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* configuration description areas, etc.
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*/
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u_long d_acylinders; /* # of alt. cylinders per unit */
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/* hardware characteristics: */
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/*
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* d_interleave, d_trackskew and d_cylskew describe perturbations
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* in the media format used to compensate for a slow controller.
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* Interleave is physical sector interleave, set up by the formatter
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* or controller when formatting. When interleaving is in use,
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* logically adjacent sectors are not physically contiguous,
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* but instead are separated by some number of sectors.
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* It is specified as the ratio of physical sectors traversed
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* per logical sector. Thus an interleave of 1:1 implies contiguous
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* layout, while 2:1 implies that logical sector 0 is separated
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* by one sector from logical sector 1.
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* d_trackskew is the offset of sector 0 on track N
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* relative to sector 0 on track N-1 on the same cylinder.
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* Finally, d_cylskew is the offset of sector 0 on cylinder N
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* relative to sector 0 on cylinder N-1.
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*/
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u_short d_rpm; /* rotational speed */
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u_short d_interleave; /* hardware sector interleave */
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u_short d_trackskew; /* sector 0 skew, per track */
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u_short d_cylskew; /* sector 0 skew, per cylinder */
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u_long d_headswitch; /* head switch time, usec */
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u_long d_trkseek; /* track-to-track seek, usec */
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u_long d_flags; /* generic flags */
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#define NDDATA 5
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u_long d_drivedata[NDDATA]; /* drive-type specific information */
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#define NSPARE 5
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u_long d_spare[NSPARE]; /* reserved for future use */
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u_long d_magic2; /* the magic number (again) */
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u_short d_checksum; /* xor of data incl. partitions */
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/* filesystem and partition information: */
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u_short d_npartitions; /* number of partitions in following */
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u_long d_bbsize; /* size of boot area at sn0, bytes */
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u_long d_sbsize; /* max size of fs superblock, bytes */
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struct partition { /* the partition table */
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u_long p_size; /* number of sectors in partition */
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u_long p_offset; /* starting sector */
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u_long p_fsize; /* filesystem basic fragment size */
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u_char p_fstype; /* filesystem type, see below */
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u_char p_frag; /* filesystem fragments per block */
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union {
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u_short cpg; /* UFS: FS cylinders per group */
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u_short sgs; /* LFS: FS segment shift */
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} __partition_u1;
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#define p_cpg __partition_u1.cpg
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#define p_sgs __partition_u1.sgs
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u_short p_cpg; /* filesystem cylinders per group */
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} d_partitions[MAXPARTITIONS]; /* actually may be more */
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};
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/* d_type values: */
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#define DTYPE_SMD 1 /* SMD, XSMD; VAX hp/up */
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#define DTYPE_MSCP 2 /* MSCP */
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#define DTYPE_DEC 3 /* other DEC (rk, rl) */
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#define DTYPE_SCSI 4 /* SCSI */
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#define DTYPE_ESDI 5 /* ESDI interface */
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#define DTYPE_ST506 6 /* ST506 etc. */
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#define DTYPE_HPIB 7 /* CS/80 on HP-IB */
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#define DTYPE_HPFL 8 /* HP Fiber-link */
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#define DTYPE_FLOPPY 10 /* floppy */
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#ifdef DKTYPENAMES
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static char *dktypenames[] = {
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"unknown",
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"SMD",
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"MSCP",
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"old DEC",
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"SCSI",
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"ESDI",
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"ST506",
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"HP-IB",
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"HP-FL",
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"type 9",
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"floppy",
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0
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};
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#define DKMAXTYPES (sizeof(dktypenames) / sizeof(dktypenames[0]) - 1)
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#endif
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/*
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* Filesystem type and version.
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* Used to interpret other filesystem-specific
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* per-partition information.
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*/
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#define FS_UNUSED 0 /* unused */
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#define FS_SWAP 1 /* swap */
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#define FS_V6 2 /* Sixth Edition */
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#define FS_V7 3 /* Seventh Edition */
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#define FS_SYSV 4 /* System V */
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#define FS_V71K 5 /* V7 with 1K blocks (4.1, 2.9) */
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#define FS_V8 6 /* Eighth Edition, 4K blocks */
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#define FS_BSDFFS 7 /* 4.2BSD fast file system */
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#define FS_MSDOS 8 /* MSDOS file system */
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#define FS_BSDLFS 9 /* 4.4BSD log-structured file system */
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#define FS_OTHER 10 /* in use, but unknown/unsupported */
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#define FS_HPFS 11 /* OS/2 high-performance file system */
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#define FS_ISO9660 12 /* ISO 9660, normally CD-ROM */
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#define FS_BOOT 13 /* partition contains bootstrap */
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#ifdef DKTYPENAMES
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static char *fstypenames[] = {
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"unused",
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"swap",
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"Version 6",
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"Version 7",
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"System V",
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"4.1BSD",
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"Eighth Edition",
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"4.2BSD",
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"MSDOS",
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"4.4LFS",
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"unknown",
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"HPFS",
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"ISO9660",
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"boot",
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0
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};
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#define FSMAXTYPES (sizeof(fstypenames) / sizeof(fstypenames[0]) - 1)
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#endif
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/*
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* flags shared by various drives:
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*/
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#define D_REMOVABLE 0x01 /* removable media */
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#define D_ECC 0x02 /* supports ECC */
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#define D_BADSECT 0x04 /* supports bad sector forw. */
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#define D_RAMDISK 0x08 /* disk emulator */
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#define D_CHAIN 0x10 /* can do back-back transfers */
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/*
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* Drive data for SMD.
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*/
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#define d_smdflags d_drivedata[0]
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#define D_SSE 0x1 /* supports skip sectoring */
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#define d_mindist d_drivedata[1]
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#define d_maxdist d_drivedata[2]
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#define d_sdist d_drivedata[3]
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/*
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* Drive data for ST506.
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*/
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#define d_precompcyl d_drivedata[0]
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#define d_gap3 d_drivedata[1] /* used only when formatting */
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/*
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* Drive data for SCSI.
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*/
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#define d_blind d_drivedata[0]
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#ifndef LOCORE
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/*
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* Structure used to perform a format
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* or other raw operation, returning data
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* and/or register values.
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* Register identification and format
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* are device- and driver-dependent.
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*/
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struct format_op {
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char *df_buf;
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int df_count; /* value-result */
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daddr_t df_startblk;
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int df_reg[8]; /* result */
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};
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/*
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* Structure used internally to retrieve
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* information about a partition on a disk.
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*/
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struct partinfo {
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struct disklabel *disklab;
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struct partition *part;
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};
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/*
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* Disk-specific ioctls.
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*/
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/* get and set disklabel; DIOCGPART used internally */
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#define DIOCGDINFO _IOR('d', 101, struct disklabel) /* get */
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#define DIOCSDINFO _IOW('d', 102, struct disklabel) /* set */
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#define DIOCWDINFO _IOW('d', 103, struct disklabel) /* set, update disk */
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#define DIOCGPART _IOW('d', 104, struct partinfo) /* get partition */
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/* do format operation, read or write */
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#define DIOCRFORMAT _IOWR('d', 105, struct format_op)
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#define DIOCWFORMAT _IOWR('d', 106, struct format_op)
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#define DIOCSSTEP _IOW('d', 107, int) /* set step rate */
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#define DIOCSRETRIES _IOW('d', 108, int) /* set # of retries */
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#define DIOCWLABEL _IOW('d', 109, int) /* write en/disable label */
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#define DIOCSBAD _IOW('d', 110, struct dkbad) /* set kernel dkbad */
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#endif LOCORE
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.Ed
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.Sh SEE ALSO
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.Xr disktab 5 ,
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.Xr disklabel 8
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.Sh HISTORY
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