1.\" $NetBSD: disklabel.5,v 1.31 2022/08/28 10:48:16 hgutch Exp $ 2.\" 3.\" Copyright (c) 1987, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Symmetric Computer Systems. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93 34.\" 35.Dd September 11, 2016 36.Dt DISKLABEL 5 37.Os 38.Sh NAME 39.Nm disklabel 40.Nd disk pack label 41.Sh SYNOPSIS 42.In sys/disklabel.h 43.Sh DESCRIPTION 44Each disk or disk pack on a system may contain a disk label 45which provides detailed information 46about the geometry of the disk and the partitions into which the disk 47is divided. 48It should be initialized when the disk is formatted, 49and may be changed later with the 50.Xr disklabel 8 51program. 52This information is used by the system disk driver and by the bootstrap 53program to determine how to program the drive 54and where to find the file systems on the disk partitions. 55Additional information is used by the file system in order 56to use the disk most efficiently and to locate important file system information. 57The description of each partition contains an identifier for the partition 58type (standard file system, swap area, etc.). 59The file system updates the in-core copy of the label if it contains 60incomplete information about the file system. 61.Pp 62The label is located in the sector number returned by the 63.Xr getlabelsector 3 64function, usually sector 0 where it may be found 65without any information about the disk geometry. 66It is at an offset (specified by the 67.Xr getlabeloffset 3 68function) 69from the beginning of the sector, to allow room for the initial bootstrap. 70The disk sector containing the label is normally made read-only 71so that it is not accidentally overwritten by pack-to-pack copies 72or swap operations; 73the 74.Dv DIOCWLABEL 75.Xr ioctl 2 , 76which is done as needed by the 77.Xr disklabel 8 78program. 79.Pp 80A copy of the in-core label for a disk can be obtained with the 81.Dv DIOCGDINFO 82.Xr ioctl 2 ; 83this works with a file descriptor for a block or character (``raw'') device 84for any partition of the disk. 85The in-core copy of the label is set by the 86.Dv DIOCSDINFO 87.Xr ioctl 2 . 88The offset of a partition cannot generally be changed while it is open, 89nor can it be made smaller while it is open. 90One exception is that any change is allowed if no label was found 91on the disk, and the driver was able to construct only a skeletal label 92without partition information. 93Finally, the 94.Dv DIOCWDINFO 95.Xr ioctl 2 96operation sets the in-core label and then updates the on-disk label; 97there must be an existing label on the disk for this operation to succeed. 98Thus, the initial label for a disk or disk pack must be installed 99by writing to the raw disk. 100All of these operations are normally done using 101.Xr disklabel 8 . 102.Pp 103The format of the disk label, as specified in 104.Pa sys/disklabel.h , 105is 106.Bd -literal 107/* 108 * Disk description table, see disktab(5) 109 */ 110#define _PATH_DISKTAB "/etc/disktab" 111 112/* 113 * Each disk has a label which includes information about the hardware 114 * disk geometry, file system partitions, and drive specific information. 115 * The location of the label, as well as the number of partitions the 116 * label can describe and the number of the "whole disk" (raw) 117 * partition are machine dependent. 118 */ 119#include <machine/disklabel.h> 120 121/* 122 * The absolute maximum number of disk partitions allowed. 123 * This is the maximum value of MAXPARTITIONS for which 'struct disklabel' 124 * is <= DEV_BSIZE bytes long. If MAXPARTITIONS is greater than this, beware. 125 */ 126#define MAXMAXPARTITIONS 22 127#if MAXPARTITIONS > MAXMAXPARTITIONS 128#warning beware: MAXPARTITIONS bigger than MAXMAXPARTITIONS 129#endif 130 131 132#define DISKMAGIC ((u_int32_t)0x82564557) /* The disk magic number */ 133 134#ifndef _LOCORE 135struct disklabel { 136 u_int32_t d_magic; /* the magic number */ 137 u_int16_t d_type; /* drive type */ 138 u_int16_t d_subtype; /* controller/d_type specific */ 139 char d_typename[16]; /* type name, e.g. "eagle" */ 140 141 /* 142 * d_packname contains the pack identifier and is returned when 143 * the disklabel is read off the disk or in-core copy. 144 * d_boot0 and d_boot1 are the (optional) names of the 145 * primary (block 0) and secondary (block 1-15) bootstraps 146 * as found in /usr/mdec. These are returned when using 147 * getdiskbyname(3) to retrieve the values from /etc/disktab. 148 */ 149 union { 150 char un_d_packname[16]; /* pack identifier */ 151 struct { 152 char *un_d_boot0; /* primary bootstrap name */ 153 char *un_d_boot1; /* secondary bootstrap name */ 154 } un_b; 155 } d_un; 156#define d_packname d_un.un_d_packname 157#define d_boot0 d_un.un_b.un_d_boot0 158#define d_boot1 d_un.un_b.un_d_boot1 159 160 /* disk geometry: */ 161 u_int32_t d_secsize; /* # of bytes per sector */ 162 u_int32_t d_nsectors; /* # of data sectors per track */ 163 u_int32_t d_ntracks; /* # of tracks per cylinder */ 164 u_int32_t d_ncylinders; /* # of data cylinders per unit */ 165 u_int32_t d_secpercyl; /* # of data sectors per cylinder */ 166 u_int32_t d_secperunit; /* # of data sectors per unit */ 167 168 /* 169 * Spares (bad sector replacements) below are not counted in 170 * d_nsectors or d_secpercyl. Spare sectors are assumed to 171 * be physical sectors which occupy space at the end of each 172 * track and/or cylinder. 173 */ 174 u_int16_t d_sparespertrack; /* # of spare sectors per track */ 175 u_int16_t d_sparespercyl; /* # of spare sectors per cylinder */ 176 /* 177 * Alternative cylinders include maintenance, replacement, 178 * configuration description areas, etc. 179 */ 180 u_int32_t d_acylinders; /* # of alt. cylinders per unit */ 181 182 /* hardware characteristics: */ 183 /* 184 * d_interleave, d_trackskew and d_cylskew describe perturbations 185 * in the media format used to compensate for a slow controller. 186 * Interleave is physical sector interleave, set up by the 187 * formatter or controller when formatting. When interleaving is 188 * in use, logically adjacent sectors are not physically 189 * contiguous, but instead are separated by some number of 190 * sectors. It is specified as the ratio of physical sectors 191 * traversed per logical sector. Thus an interleave of 1:1 192 * implies contiguous layout, while 2:1 implies that logical 193 * sector 0 is separated by one sector from logical sector 1. 194 * d_trackskew is the offset of sector 0 on track N relative to 195 * sector 0 on track N-1 on the same cylinder. Finally, d_cylskew 196 * is the offset of sector 0 on cylinder N relative to sector 0 197 * on cylinder N-1. 198 */ 199 u_int16_t d_rpm; /* rotational speed */ 200 u_int16_t d_interleave; /* hardware sector interleave */ 201 u_int16_t d_trackskew; /* sector 0 skew, per track */ 202 u_int16_t d_cylskew; /* sector 0 skew, per cylinder */ 203 u_int32_t d_headswitch; /* head switch time, usec */ 204 u_int32_t d_trkseek; /* track-to-track seek, usec */ 205 u_int32_t d_flags; /* generic flags */ 206#define NDDATA 5 207 u_int32_t d_drivedata[NDDATA]; /* drive-type specific information */ 208#define NSPARE 5 209 u_int32_t d_spare[NSPARE]; /* reserved for future use */ 210 u_int32_t d_magic2; /* the magic number (again) */ 211 u_int16_t d_checksum; /* xor of data incl. partitions */ 212 213 /* file system and partition information: */ 214 u_int16_t d_npartitions; /* number of partitions in following */ 215 u_int32_t d_bbsize; /* size of boot area at sn0, bytes */ 216 u_int32_t d_sbsize; /* max size of fs superblock, bytes */ 217 struct partition { /* the partition table */ 218 u_int32_t p_size; /* number of sectors in partition */ 219 u_int32_t p_offset; /* starting sector */ 220 u_int32_t p_fsize; /* file system basic fragment size */ 221 u_int8_t p_fstype; /* file system type, see below */ 222 u_int8_t p_frag; /* file system fragments per block */ 223 union { 224 u_int16_t cpg; /* UFS: FS cylinders per group */ 225 u_int16_t sgs; /* LFS: FS segment shift */ 226 } __partition_u1; 227#define p_cpg __partition_u1.cpg 228#define p_sgs __partition_u1.sgs 229 } d_partitions[MAXPARTITIONS]; /* actually may be more */ 230}; 231#else /* _LOCORE */ 232 /* 233 * offsets for asm boot files. 234 */ 235 .set d_secsize,40 236 .set d_nsectors,44 237 .set d_ntracks,48 238 .set d_ncylinders,52 239 .set d_secpercyl,56 240 .set d_secperunit,60 241 .set d_end_,276 /* size of disk label */ 242#endif /* _LOCORE */ 243 244/* d_type values: */ 245#define DTYPE_SMD 1 /* SMD, XSMD; VAX hp/up */ 246#define DTYPE_MSCP 2 /* MSCP */ 247#define DTYPE_DEC 3 /* other DEC (rk, rl) */ 248#define DTYPE_SCSI 4 /* SCSI */ 249#define DTYPE_ESDI 5 /* ESDI interface */ 250#define DTYPE_ST506 6 /* ST506 etc. */ 251#define DTYPE_HPIB 7 /* CS/80 on HP-IB */ 252#define DTYPE_HPFL 8 /* HP Fiber-link */ 253#define DTYPE_FLOPPY 10 /* floppy */ 254#define DTYPE_CCD 11 /* concatenated disk device */ 255#define DTYPE_VND 12 /* vnode pseudo-disk */ 256#define DTYPE_ATAPI 13 /* ATAPI */ 257#define DTYPE_RAID 14 /* RAIDframe */ 258#define DTYPE_LD 15 /* logical disk */ 259#define DTYPE_JFS2 16 /* IBM JFS2 */ 260#define DTYPE_CGD 17 /* cryptographic pseudo-disk */ 261#define DTYPE_VINUM 18 /* vinum volume obsolete */ 262#define DTYPE_FLASH 19 /* flash memory device */ 263 264#ifdef DKTYPENAMES 265static const char *const dktypenames[] = { 266 "unknown", 267 "SMD", 268 "MSCP", 269 "old DEC", 270 "SCSI", 271 "ESDI", 272 "ST506", 273 "HP-IB", 274 "HP-FL", 275 "type 9", 276 "floppy", 277 "ccd", 278 "vnd", 279 "ATAPI", 280 "RAID", 281 "ld", 282 "jfs", 283 "cgd", 284 "obsolete vinum", 285 "flash", 286 NULL 287}; 288#define DKMAXTYPES (sizeof(dktypenames) / sizeof(dktypenames[0]) - 1) 289#endif 290 291/* 292 * Filesystem type and version. 293 * Used to interpret other file system-specific 294 * per-partition information. 295 */ 296#define FS_UNUSED 0 /* unused */ 297#define FS_SWAP 1 /* swap */ 298#define FS_V6 2 /* Sixth Edition */ 299#define FS_V7 3 /* Seventh Edition */ 300#define FS_SYSV 4 /* System V */ 301#define FS_V71K 5 /* V7 with 1K blocks (4.1, 2.9) */ 302#define FS_V8 6 /* Eighth Edition, 4K blocks */ 303#define FS_BSDFFS 7 /* 4.2BSD fast file system */ 304#define FS_MSDOS 8 /* MSDOS file system */ 305#define FS_BSDLFS 9 /* 4.4BSD log-structured file system */ 306#define FS_OTHER 10 /* in use, but unknown/unsupported */ 307#define FS_HPFS 11 /* OS/2 high-performance file system */ 308#define FS_ISO9660 12 /* ISO 9660, normally CD-ROM */ 309#define FS_BOOT 13 /* partition contains bootstrap */ 310#define FS_ADOS 14 /* AmigaDOS fast file system */ 311#define FS_HFS 15 /* Macintosh HFS */ 312#define FS_FILECORE 16 /* Acorn Filecore Filing System */ 313#define FS_EX2FS 17 /* Linux Extended 2 file system */ 314#define FS_NTFS 18 /* Windows/NT file system */ 315#define FS_RAID 19 /* RAIDframe component */ 316#define FS_CCD 20 /* concatenated disk component */ 317#define FS_JFS2 21 /* IBM JFS2 */ 318#define FS_APPLEUFS 22 /* Apple UFS */ 319#define FS_VINUM 23 /* Vinum */ 320 321#ifdef FSTYPENAMES 322static const char *const fstypenames[] = { 323 "unused", 324 "swap", 325 "Version 6", 326 "Version 7", 327 "System V", 328 "4.1BSD", 329 "Eighth Edition", 330 "4.2BSD", 331 "MSDOS", 332 "4.4LFS", 333 "unknown", 334 "HPFS", 335 "ISO9660", 336 "boot", 337 "ADOS", 338 "HFS", 339 "FILECORE", 340 "Linux Ext2", 341 "NTFS", 342 "RAID", 343 "ccd", 344 "jfs", 345 "Apple UFS", 346 "obsolete vinum", 347 NULL 348}; 349#define FSMAXTYPES (sizeof(fstypenames) / sizeof(fstypenames[0]) - 1) 350#endif 351 352/* 353 * flags shared by various drives: 354 */ 355#define D_REMOVABLE 0x01 /* removable media */ 356#define D_ECC 0x02 /* supports ECC */ 357#define D_BADSECT 0x04 /* supports bad sector forw. */ 358#define D_RAMDISK 0x08 /* disk emulator */ 359#define D_CHAIN 0x10 /* can do back-back transfers */ 360 361/* 362 * Drive data for SMD. 363 */ 364 365#define d_smdflags d_drivedata[0] 366#define D_SSE 0x1 /* supports skip sectoring */ 367#define d_mindist d_drivedata[1] 368#define d_maxdist d_drivedata[2] 369#define d_sdist d_drivedata[3] 370 371/* 372 * Drive data for ST506. 373 */ 374#define d_precompcyl d_drivedata[0] 375#define d_gap3 d_drivedata[1] /* used only when formatting */ 376 377/* 378 * Drive data for SCSI. 379 */ 380#define d_blind d_drivedata[0] 381 382#ifndef _LOCORE 383/* 384 * Structure used to perform a format or other raw operation, 385 * returning data and/or register values. Register identification 386 * and format are device- and driver-dependent. 387 */ 388struct format_op { 389 char *df_buf; 390 int df_count; /* value-result */ 391 daddr_t df_startblk; 392 int df_reg[8]; /* result */ 393}; 394 395/* 396 * Structure used internally to retrieve information about a partition 397 * on a disk. 398 */ 399struct partinfo { 400 struct disklabel *disklab; 401 struct partition *part; 402}; 403.Ed 404.Pp 405Disk specific ioctls are defined in 406.Pa sys/dkio.h . 407.Bd -literal 408.Pp 409/* 410 * Disk-specific ioctls. 411 */ 412 /* get and set disklabel; DIOCGPART used internally */ 413#define DIOCGDINFO _IOR('d', 101, struct disklabel) /* get */ 414#define DIOCSDINFO _IOW('d', 102, struct disklabel) /* set */ 415#define DIOCWDINFO _IOW('d', 103, struct disklabel) /* set, update disk */ 416#define DIOCGPART _IOW('d', 104, struct partinfo) /* get partition */ 417 418 /* do format operation, read or write */ 419#define DIOCRFORMAT _IOWR('d', 105, struct format_op) 420#define DIOCWFORMAT _IOWR('d', 106, struct format_op) 421 422#define DIOCSSTEP _IOW('d', 107, int) /* set step rate */ 423#define DIOCSRETRIES _IOW('d', 108, int) /* set # of retries */ 424#define DIOCKLABEL _IOW('d', 119, int) /* keep/drop label on close? */ 425#define DIOCWLABEL _IOW('d', 109, int) /* write en/disable label */ 426 427#define DIOCSBAD _IOW('d', 110, struct dkbad) /* set kernel dkbad */ 428#define DIOCEJECT _IOW('d', 112, int) /* eject removable disk */ 429#define DIOCLOCK _IOW('d', 113, int) /* lock/unlock pack */ 430 431 /* get default label, clear label */ 432#define DIOCGDEFLABEL _IOR('d', 114, struct disklabel) 433#define DIOCCLRLABEL _IO('d', 115) 434.Ed 435.Sh SEE ALSO 436.Xr disktab 5 , 437.Xr disklabel 8 , 438.Xr dkctl 8 439.\" .Sh HISTORY 440