.\" Copyright (c) 1987, 1991, 1993
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.\" This code is derived from software contributed to Berkeley by
.\" Symmetric Computer Systems.
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.\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93
.\" $FreeBSD$
.\"
.Dd June 5, 1993
.Dt DISKLABEL 5
.Os
.Sh NAME
.Nm disklabel
.Nd disk pack label
.Sh SYNOPSIS
.In sys/disklabel.h
.Sh DESCRIPTION
Each disk or disk pack on a system may contain a disk label
which provides detailed information
about the geometry of the disk and the partitions into which the disk
is divided.
It should be initialized when the disk is formatted,
and may be changed later with the
.Xr disklabel 8
program.
This information is used by the system disk driver and by the bootstrap
program to determine how to program the drive
and where to find the file systems on the disk partitions.
Additional information is used by the file system in order
to use the disk most efficiently and to locate important file system information.
The description of each partition contains an identifier for the partition
type (standard file system, swap area, etc.).
The file system updates the in-core copy of the label if it contains
incomplete information about the file system.
.Pp
The label is located in sector number
.Dv LABELSECTOR
of the drive, usually sector 0 where it may be found
without any information about the disk geometry.
It is at an offset
.Dv LABELOFFSET
from the beginning of the sector, to allow room for the initial bootstrap.
The disk sector containing the label is normally made read-only
so that it is not accidentally overwritten by pack-to-pack copies
or swap operations;
the
.Dv DIOCWLABEL
.Xr ioctl 2 ,
which is done as needed by the
.Xr disklabel 8
program.
.Pp
A copy of the in-core label for a disk can be obtained with the
.Dv DIOCGDINFO
.Xr ioctl 2 ;
this works with a file descriptor for a block or character (``raw'') device
for any partition of the disk.
The in-core copy of the label is set by the
.Dv DIOCSDINFO
.Xr ioctl 2 .
The offset of a partition cannot generally be changed while it is open,
nor can it be made smaller while it is open.
One exception is that any change is allowed if no label was found
on the disk, and the driver was able to construct only a skeletal label
without partition information.
Finally, the
.Dv DIOCWDINFO
.Xr ioctl 2
operation sets the in-core label and then updates the on-disk label;
there must be an existing label on the disk for this operation to succeed.
Thus, the initial label for a disk or disk pack must be installed
by writing to the raw disk.
All of these operations are normally done using
.Xr disklabel 8 .
.Pp
The format of the disk label, as specified in
.In sys/disklabel.h ,
is
.Bd -literal
#ifndef _SYS_DISKLABEL_H_
#define _SYS_DISKLABEL_H_
#ifndef _KERNEL
#include <sys/types.h>
#endif
#include <sys/ioccom.h>
/*
* Disk description table, see disktab(5)
*/
#define _PATH_DISKTAB "/etc/disktab"
#define DISKTAB "/etc/disktab" /* deprecated */
/*
* Each disk has a label which includes information about the hardware
* disk geometry, file system partitions, and drive specific information.
* The label is in block 0 or 1, possibly offset from the beginning
* to leave room for a bootstrap, etc.
*/
/* XXX these should be defined per controller (or drive) elsewhere, not here! */
#ifdef __i386__
#define LABELSECTOR 1 /* sector containing label */
#define LABELOFFSET 0 /* offset of label in sector */
#endif
#ifdef __alpha__
#define LABELSECTOR 0
#define LABELOFFSET 64
#endif
#ifndef LABELSECTOR
#define LABELSECTOR 0 /* sector containing label */
#endif
#ifndef LABELOFFSET
#define LABELOFFSET 64 /* offset of label in sector */
#endif
#define DISKMAGIC ((u_int32_t)0x82564557) /* The disk magic number */
#ifndef MAXPARTITIONS
#define MAXPARTITIONS 8
#endif
#define LABEL_PART 2 /* partition containing label */
#define RAW_PART 2 /* partition containing whole disk */
#define SWAP_PART 1 /* partition normally containing swap */
#ifndef LOCORE
struct disklabel {
u_int32_t d_magic; /* the magic number */
u_int16_t d_type; /* drive type */
u_int16_t d_subtype; /* controller/d_type specific */
char d_typename[16]; /* type name, e.g. "eagle" */
char d_packname[16]; /* pack identifier */
/* disk geometry: */
u_int32_t d_secsize; /* # of bytes per sector */
u_int32_t d_nsectors; /* # of data sectors per track */
u_int32_t d_ntracks; /* # of tracks per cylinder */
u_int32_t d_ncylinders; /* # of data cylinders per unit */
u_int32_t d_secpercyl; /* # of data sectors per cylinder */
u_int32_t d_secperunit; /* # of data sectors per unit */
/*
* Spares (bad sector replacements) below are not counted in
* d_nsectors or d_secpercyl. Spare sectors are assumed to
* be physical sectors which occupy space at the end of each
* track and/or cylinder.
*/
u_int16_t d_sparespertrack; /* # of spare sectors per track */
u_int16_t d_sparespercyl; /* # of spare sectors per cylinder */
/*
* Alternate cylinders include maintenance, replacement, configuration
* description areas, etc.
*/
u_int32_t d_acylinders; /* # of alt. cylinders per unit */
/* hardware characteristics: */
/*
* d_interleave, d_trackskew and d_cylskew describe perturbations
* in the media format used to compensate for a slow controller.
* Interleave is physical sector interleave, set up by the
* formatter or controller when formatting. When interleaving is
* in use, logically adjacent sectors are not physically
* contiguous, but instead are separated by some number of
* sectors. It is specified as the ratio of physical sectors
* traversed per logical sector. Thus an interleave of 1:1
* implies contiguous layout, while 2:1 implies that logical
* sector 0 is separated by one sector from logical sector 1.
* d_trackskew is the offset of sector 0 on track N relative to
* sector 0 on track N-1 on the same cylinder. Finally, d_cylskew
* is the offset of sector 0 on cylinder N relative to sector 0
* on cylinder N-1.
*/
u_int16_t d_rpm; /* rotational speed */
u_int16_t d_interleave; /* hardware sector interleave */
u_int16_t d_trackskew; /* sector 0 skew, per track */
u_int16_t d_cylskew; /* sector 0 skew, per cylinder */
u_int32_t d_headswitch; /* head switch time, usec */
u_int32_t d_trkseek; /* track-to-track seek, usec */
u_int32_t d_flags; /* generic flags */
#define NDDATA 5
u_int32_t d_drivedata[NDDATA]; /* drive-type specific information */
#define NSPARE 5
u_int32_t d_spare[NSPARE]; /* reserved for future use */
u_int32_t d_magic2; /* the magic number (again) */
u_int16_t d_checksum; /* xor of data incl. partitions */
/* file system and partition information: */
u_int16_t d_npartitions; /* number of partitions in following */
u_int32_t d_bbsize; /* size of boot area at sn0, bytes */
u_int32_t d_sbsize; /* max size of fs superblock, bytes */
struct partition { /* the partition table */
u_int32_t p_size; /* number of sectors in partition */
u_int32_t p_offset; /* starting sector */
u_int32_t p_fsize; /* file system basic fragment size */
u_int8_t p_fstype; /* file system type, see below */
u_int8_t p_frag; /* file system fragments per block */
union {
u_int16_t cpg; /* UFS: FS cylinders per group */
u_int16_t sgs; /* LFS: FS segment shift */
} __partition_u1;
#define p_cpg __partition_u1.cpg
#define p_sgs __partition_u1.sgs
} d_partitions[MAXPARTITIONS]; /* actually may be more */
};
#else /* LOCORE */
/*
* offsets for asm boot files.
*/
.set d_secsize,40
.set d_nsectors,44
.set d_ntracks,48
.set d_ncylinders,52
.set d_secpercyl,56
.set d_secperunit,60
.set d_end_,276 /* size of disk label */
#endif /* LOCORE */
/* d_type values: */
#define DTYPE_SMD 1 /* SMD, XSMD; VAX hp/up */
#define DTYPE_MSCP 2 /* MSCP */
#define DTYPE_DEC 3 /* other DEC (rk, rl) */
#define DTYPE_SCSI 4 /* SCSI */
#define DTYPE_ESDI 5 /* ESDI interface */
#define DTYPE_ST506 6 /* ST506 etc. */
#define DTYPE_HPIB 7 /* CS/80 on HP-IB */
#define DTYPE_HPFL 8 /* HP Fiber-link */
#define DTYPE_FLOPPY 10 /* floppy */
#define DTYPE_CCD 11 /* concatenated disk */
#define DTYPE_VINUM 12 /* vinum volume */
#define DTYPE_DOC2K 13 /* Msys DiskOnChip */
#if defined(PC98) && !defined(PC98_ATCOMPAT)
#define DSTYPE_SEC256 0x80 /* physical sector size=256 */
#endif
#ifdef DKTYPENAMES
static char *dktypenames[] = {
"unknown",
"SMD",
"MSCP",
"old DEC",
"SCSI",
"ESDI",
"ST506",
"HP-IB",
"HP-FL",
"type 9",
"floppy",
"CCD",
"Vinum",
"DOC2K",
NULL
};
#define DKMAXTYPES (sizeof(dktypenames) / sizeof(dktypenames[0]) - 1)
#endif
/*
* File system type and version.
* Used to interpret other file system-specific
* per-partition information.
*/
#define FS_UNUSED 0 /* unused */
#define FS_SWAP 1 /* swap */
#define FS_V6 2 /* Sixth Edition */
#define FS_V7 3 /* Seventh Edition */
#define FS_SYSV 4 /* System V */
#define FS_V71K 5 /* V7 with 1K blocks (4.1, 2.9) */
#define FS_V8 6 /* Eighth Edition, 4K blocks */
#define FS_BSDFFS 7 /* 4.2BSD fast file system */
#define FS_MSDOS 8 /* MSDOS file system */
#define FS_BSDLFS 9 /* 4.4BSD log-structured file system */
#define FS_OTHER 10 /* in use, but unknown/unsupported */
#define FS_HPFS 11 /* OS/2 high-performance file system */
#define FS_ISO9660 12 /* ISO 9660, normally CD-ROM */
#define FS_BOOT 13 /* partition contains bootstrap */
#define FS_VINUM 14 /* Vinum drive */
#ifdef DKTYPENAMES
static char *fstypenames[] = {
"unused",
"swap",
"Version 6",
"Version 7",
"System V",
"4.1BSD",
"Eighth Edition",
"4.2BSD",
"MSDOS",
"4.4LFS",
"unknown",
"HPFS",
"ISO9660",
"boot",
"vinum",
NULL
};
#define FSMAXTYPES (sizeof(fstypenames) / sizeof(fstypenames[0]) - 1)
#endif
/*
* flags shared by various drives:
*/
#define D_REMOVABLE 0x01 /* removable media */
#define D_ECC 0x02 /* supports ECC */
#define D_BADSECT 0x04 /* supports bad sector forw. */
#define D_RAMDISK 0x08 /* disk emulator */
#define D_CHAIN 0x10 /* can do back-back transfers */
/*
* Drive data for SMD.
*/
#define d_smdflags d_drivedata[0]
#define D_SSE 0x1 /* supports skip sectoring */
#define d_mindist d_drivedata[1]
#define d_maxdist d_drivedata[2]
#define d_sdist d_drivedata[3]
/*
* Drive data for ST506.
*/
#define d_precompcyl d_drivedata[0]
#define d_gap3 d_drivedata[1] /* used only when formatting */
/*
* Drive data for SCSI.
*/
#define d_blind d_drivedata[0]
#ifndef LOCORE
/*
* Structure used to perform a format or other raw operation, returning
* data and/or register values. Register identification and format
* are device- and driver-dependent.
*/
struct format_op {
char *df_buf;
int df_count; /* value-result */
daddr_t df_startblk;
int df_reg[8]; /* result */
};
/*
* Structure used internally to retrieve information about a partition
* on a disk.
*/
struct partinfo {
struct disklabel *disklab;
struct partition *part;
};
/* DOS partition table -- located in boot block */
#if defined(PC98) && !defined(PC98_ATCOMPAT)
#define DOSBBSECTOR 0 /* DOS boot block relative sector number */
#define DOSLABELSECTOR 1 /* 0: 256b/s, 1: 512b/s */
#define DOSPARTOFF 0
#define NDOSPART 16
#define DOSPTYP_386BSD 0x94 /* 386BSD partition type */
#define MBR_PTYPE_FreeBSD 0x94 /* FreeBSD partition type */
struct dos_partition {
unsigned char dp_mid;
#define DOSMID_386BSD (0x14|0x80) /* 386bsd|bootable */
unsigned char dp_sid;
#define DOSSID_386BSD (0x44|0x80) /* 386bsd|active */
unsigned char dp_dum1;
unsigned char dp_dum2;
unsigned char dp_ipl_sct;
unsigned char dp_ipl_head;
unsigned short dp_ipl_cyl;
unsigned char dp_ssect; /* starting sector */
unsigned char dp_shd; /* starting head */
unsigned short dp_scyl; /* starting cylinder */
unsigned char dp_esect; /* end sector */
unsigned char dp_ehd; /* end head */
unsigned short dp_ecyl; /* end cylinder */
unsigned char dp_name[16];
};
#else /* IBMPC */
#define DOSBBSECTOR 0 /* DOS boot block relative sector number */
#define DOSPARTOFF 446
#define NDOSPART 4
#define DOSPTYP_386BSD 0xa5 /* 386BSD partition type */
struct dos_partition {
unsigned char dp_flag; /* bootstrap flags */
unsigned char dp_shd; /* starting head */
unsigned char dp_ssect; /* starting sector */
unsigned char dp_scyl; /* starting cylinder */
unsigned char dp_typ; /* partition type */
unsigned char dp_ehd; /* end head */
unsigned char dp_esect; /* end sector */
unsigned char dp_ecyl; /* end cylinder */
u_int32_t dp_start; /* absolute starting sector number */
u_int32_t dp_size; /* partition size in sectors */
};
#endif
#define DPSECT(s) ((s) & 0x3f) /* isolate relevant bits of sector */
#define DPCYL(c, s) ((c) + (((s) & 0xc0)<<2)) /* and those that are cylinder */
/*
* Disk-specific ioctls.
*/
/* get and set disklabel; DIOCGPART used internally */
#define DIOCGDINFO _IOR('d', 101, struct disklabel)/* get */
#define DIOCSDINFO _IOW('d', 102, struct disklabel)/* set */
#define DIOCWDINFO _IOW('d', 103, struct disklabel)/* set, update disk */
#define DIOCGPART _IOW('d', 104, struct partinfo) /* get partition */
#define DIOCWLABEL _IOW('d', 109, int) /* write en/disable label */
#ifdef _KERNEL
/*
* XXX encoding of disk minor numbers, should be elsewhere.
*
* See <sys/reboot.h> for a possibly better encoding.
*
* "cpio -H newc" can be used to back up device files with large minor
* numbers (but not ones >= 2^31). Old cpio formats and all tar formats
* don't have enough bits, and cpio and tar don't notice the lossage.
* There are also some sign extension bugs.
*/
/*
3 2 1 0
1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
_________________________________________________________________
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
-----------------------------------------------------------------
| TYPE |UNIT_2 | SLICE | MAJOR? | UNIT |PART |
-----------------------------------------------------------------
*/
#define dkmakeminor(unit, slice, part) \e
(((slice) << 16) | (((unit) & 0x1e0) << 16) | \e
(((unit) & 0x1f) << 3) | (part))
static __inline dev_t
dkmodpart(dev_t dev, int part)
{
return (makedev(major(dev), (minor(dev) & ~7) | part));
}
static __inline dev_t
dkmodslice(dev_t dev, int slice)
{
return (makedev(major(dev), (minor(dev) & ~0x1f0000) | (slice << 16)));
}
#define dkpart(dev) (minor(dev) & 7)
#define dkslice(dev) ((minor(dev) >> 16) & 0x1f)
#define dktype(dev) ((minor(dev) >> 25) & 0x7f)
static __inline u_int
dkunit(dev_t dev)
{
return (((minor(dev) >> 16) & 0x1e0) | ((minor(dev) >> 3) & 0x1f));
}
struct buf;
struct buf_queue_head;
int bounds_check_with_label(struct buf *bp, struct disklabel *lp,
int wlabel);
void diskerr(struct buf *bp, char *what, int pri, int blkdone,
struct disklabel *lp);
void disksort(struct buf *ap, struct buf *bp);
u_int dkcksum struct disklabel *lp);
char *readdisklabel(dev_t dev, struct disklabel *lp);
void bufqdisksort(struct buf_queue_head *ap, struct buf *bp);
int setdisklabel(struct disklabel *olp, struct disklabel *nlp,
u_long openmask);
int writedisklabel(dev_t dev, struct disklabel *lp);
#ifdef __alpha__
void alpha_fix_srm_checksum(struct buf *bp);
#endif
#endif /* _KERNEL */
#endif /* LOCORE */
#ifndef _KERNEL
__BEGIN_DECLS
struct disklabel *getdiskbyname(const char *);
__END_DECLS
#endif
#endif /* !_SYS_DISKLABEL_H_ */
.Ed
.Sh SEE ALSO
.Xr disktab 5 ,
.Xr disklabel 8
