1.\" $OpenBSD: disklabel.5,v 1.11 2001/08/12 12:03:01 heko Exp $ 2.\" $NetBSD: disklabel.5,v 1.3 1995/03/18 14:54:36 cgd Exp $ 3.\" 4.\" Copyright (c) 1987, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" Symmetric Computer Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93 39.\" 40.Dd August 6, 2001 41.Dt DISKLABEL 5 42.Os 43.Sh NAME 44.Nm disklabel 45.Nd disk pack label 46.Sh SYNOPSIS 47.Fd #include <sys/disklabel.h> 48.Sh DESCRIPTION 49Each disk or disk pack on a system may contain a disk label 50which provides detailed information 51about the geometry of the disk and the partitions into which the disk 52is divided. 53It should be initialized when the disk is formatted, 54and may be changed later with the 55.Xr disklabel 8 56program. 57This information is used by the system disk driver and by the bootstrap 58program to determine how to program the drive 59and where to find the filesystems on the disk partitions. 60Additional information is used by the filesystem in order 61to use the disk most efficiently and to locate important filesystem information. 62The description of each partition contains an identifier for the partition 63type (standard filesystem, swap area, etc.). 64The filesystem updates the in-core copy of the label if it contains 65incomplete information about the filesystem. 66.Pp 67The label is located in sector number 68.Dv LABELSECTOR 69of the drive, usually sector 0 where it may be found 70without any information about the disk geometry. 71It is at an offset 72.Dv LABELOFFSET 73from the beginning of the sector, to allow room for the initial bootstrap. 74The disk sector containing the label is normally made read-only 75so that it is not accidentally overwritten by pack-to-pack copies 76or swap operations; 77the 78.Dv DIOCWLABEL 79.Xr ioctl 2 , 80which is done as needed by the 81.Xr disklabel 82program, allows modification of the label sector. 83.Pp 84A copy of the in-core label for a disk can be obtained with the 85.Dv DIOCGDINFO 86.Xr ioctl ; 87this works with a file descriptor for a block or character 88.Pq Dq raw 89device for any partition of the disk. 90The in-core copy of the label is set by the 91.Dv DIOCSDINFO 92.Xr ioctl . 93The offset of a partition cannot generally be changed while it is open, 94nor can it be made smaller while it is open. 95One exception is that any change is allowed if no label was found 96on the disk, and the driver was able to construct only a skeletal label 97without partition information. 98The 99.Dv DIOCWDINFO 100.Xr ioctl 101operation sets the in-core label and then updates the on-disk label; 102there must be an existing label on the disk for this operation to succeed. 103Thus, the initial label for a disk or disk pack must be installed 104by writing to the raw disk. 105The 106.Dv DIOCGPDINFO 107.Xr ioctl 108operation gets the default label for a disk. This simulates the case 109where there is no physical label on the disk itself and can be used to 110see the label the kernel would construct in that case. 111The 112.Dv DIOCRLDINFO 113.Xr ioctl 114operation causes the kernel to update its copy of label based on the 115physical label on the disk. It can be used when the on-disk version 116of the label was changed directly or, if there is no physical label, 117to update the kernel's skeletal label if some variable affecting label 118generation has changed (e.g. the fdisk partition table). 119All of these operations are normally done using 120.Xr disklabel . 121.Pp 122The format of the disk label, as specified in 123.Pa sys/disklabel.h , 124is 125.Bd -literal 126/* 127 * Disk description table, see disktab(5) 128 */ 129#define DISKTAB "/etc/disktab" 130 131/* 132 * Each disk has a label which includes information about the hardware 133 * disk geometry, filesystem partitions, and drive specific information. 134 * The label is in block 0 or 1, possibly offset from the beginning 135 * to leave room for a bootstrap, etc. 136 */ 137 138#ifndef LABELSECTOR 139#define LABELSECTOR 0 /* sector containing label */ 140#endif 141 142#ifndef LABELOFFSET 143#define LABELOFFSET 64 /* offset of label in sector */ 144#endif 145 146#define DISKMAGIC ((u_int32_t)0x82564557) /* disk magic number */ 147 148#ifndef LOCORE 149struct disklabel { 150 u_int32_t d_magic; /* the magic number */ 151 u_int16_t d_type; /* drive type */ 152 u_int16_t d_subtype; /* controller/d_type specific */ 153 char d_typename[16]; /* type name, e.g., "eagle" */ 154 /* 155 * d_packname contains the pack identifier and is returned when 156 * the disklabel is read off the disk or in-core copy. 157 * d_boot0 and d_boot1 are the (optional) names of the 158 * primary (block 0) and secondary (block 1-15) bootstraps 159 * as found in /usr/mdec. These are returned when using 160 * getdiskbyname(3) to retrieve the values from /etc/disktab. 161 */ 162 union { 163 char un_d_packname[16]; /* pack identifier */ 164 struct { 165 char *un_d_boot0; /* primary bootstrap name */ 166 char *un_d_boot1; /* secondary bootstrap name */ 167 } un_b; 168 } d_un; 169#define d_packname d_un.un_d_packname 170#define d_boot0 d_un.un_b.un_d_boot0 171#define d_boot1 d_un.un_b.un_d_boot1 172 173 /* disk geometry: */ 174 u_int32_t d_secsize; /* # of bytes per sector */ 175 u_int32_t d_nsectors; /* # of data sectors per track */ 176 u_int32_t d_ntracks; /* # of tracks per cylinder */ 177 u_int32_t d_ncylinders; /* # of data cylinders per unit */ 178 u_int32_t d_secpercyl; /* # of data sectors per cylinder */ 179 u_int32_t d_secperunit; /* # of data sectors per unit */ 180 /* 181 * Spares (bad sector replacements) below 182 * are not counted in d_nsectors or d_secpercyl. 183 * Spare sectors are assumed to be physical sectors 184 * which occupy space at the end of each track and/or cylinder. 185 */ 186 u_int16_t d_sparespertrack; /* # of spare sects per track */ 187 u_int16_t d_sparespercyl; /* # of spare sects per cylinder */ 188 /* 189 * Alternate cylinders include maintenance, replacement, 190 * configuration description areas, etc. 191 */ 192 u_int32_t d_acylinders; /* # of alt. cylinders per unit */ 193 194 /* hardware characteristics: */ 195 /* 196 * d_interleave, d_trackskew and d_cylskew describe perturbations 197 * in the media format used to compensate for a slow controller. 198 * Interleave is physical sector interleave, set up by the 199 * formatter or controller when formatting. When interleaving is 200 * in use, logically adjacent sectors are not physically 201 * contiguous, but instead are separated by some number of sectors. 202 * It is specified as the ratio of physical sectors traversed 203 * per logical sector. Thus an interleave of 1:1 implies 204 * contiguous layout, while 2:1 implies that logical sector 0 is 205 * separated by one sector from logical sector 1. 206 * d_trackskew is the offset of sector 0 on track N 207 * relative to sector 0 on track N-1 on the same cylinder. 208 * Finally, d_cylskew is the offset of sector 0 on cylinder N 209 * relative to sector 0 on cylinder N-1. 210 */ 211 u_int16_t d_rpm; /* rotational speed */ 212 u_int16_t d_interleave; /* hardware sector interleave */ 213 u_int16_t d_trackskew; /* sector 0 skew, per track */ 214 u_int16_t d_cylskew; /* sector 0 skew, per cylinder */ 215 u_int32_t d_headswitch; /* head switch time, usec */ 216 u_int32_t d_trkseek; /* track-to-track seek, usec */ 217 u_int32_t d_flags; /* generic flags */ 218#define NDDATA 5 219 u_int32_t d_drivedata[NDDATA]; /* drive-type specific info */ 220#define NSPARE 5 221 u_int32_t d_spare[NSPARE];/* reserved for future use */ 222 u_int32_t d_magic2; /* the magic number (again) */ 223 u_int16_t d_checksum; /* xor of data incl. partitions */ 224 225 /* filesystem and partition information: */ 226 u_int16_t d_npartitions; /* # of partitions in following */ 227 u_int32_t d_bbsize; /* size of boot area at sn0, bytes */ 228 u_int32_t d_sbsize; /* max size of fs superblock, bytes */ 229 struct partition { /* the partition table */ 230 u_int32_t p_size; /* number of sectors in partition */ 231 u_int32_t p_offset; /* starting sector */ 232 u_int32_t p_fsize; /* filesystem basic frag size */ 233 u_int8_t p_fstype; /* filesystem type, see below */ 234 u_int8_t p_frag; /* filesystem frags per block */ 235 union { 236 u_int16_t cpg; /* UFS: FS cyls per group */ 237 u_int16_t sgs; /* LFS: FS segment shift */ 238 } __partition_u1; 239#define p_cpg __partition_u1.cpg 240#define p_sgs __partition_u1.sgs 241 } d_partitions[MAXPARTITIONS]; /* actually may be more, 242 * MAXPARTITIONS depends on the 243 * architecture, and typically 244 * varies between 8 and 16. 245 */ 246}; 247 248/* d_type values: */ 249#define DTYPE_SMD 1 /* SMD, XSMD; VAX hp/up */ 250#define DTYPE_MSCP 2 /* MSCP */ 251#define DTYPE_DEC 3 /* other DEC (rk, rl) */ 252#define DTYPE_SCSI 4 /* SCSI */ 253#define DTYPE_ESDI 5 /* ESDI interface */ 254#define DTYPE_ST506 6 /* ST506 etc. */ 255#define DTYPE_HPIB 7 /* CS/80 on HP-IB */ 256#define DTYPE_HPFL 8 /* HP Fiber-link */ 257#define DTYPE_FLOPPY 10 /* floppy */ 258#define DTYPE_CCD 11 /* concatenated disk device */ 259#define DTYPE_VND 12 /* vnode pseudo-disk */ 260#define DTYPE_ATAPI 13 /* ATAPI */ 261#define DTYPE_RAID 14 /* RAIDframe */ 262 263#ifdef DKTYPENAMES 264static char *dktypenames[] = { 265 "unknown", 266 "SMD", 267 "MSCP", 268 "old DEC", 269 "SCSI", 270 "ESDI", 271 "ST506", 272 "HP-IB", 273 "HP-FL", 274 "type 9", 275 "floppy", 276 "ccd", 277 "vnd", 278 "ATAPI", 279 "RAID", 280 NULL 281}; 282#define DKMAXTYPES (sizeof(dktypenames) / sizeof(dktypenames[0]) - 1) 283#endif 284 285/* 286 * Filesystem type and version. 287 * Used to interpret other filesystem-specific 288 * per-partition information. 289 */ 290#define FS_UNUSED 0 /* unused */ 291#define FS_SWAP 1 /* swap */ 292#define FS_V6 2 /* Sixth Edition */ 293#define FS_V7 3 /* Seventh Edition */ 294#define FS_SYSV 4 /* System V */ 295#define FS_V71K 5 /* V7 with 1K blocks (4.1, 2.9) */ 296#define FS_V8 6 /* Eighth Edition, 4K blocks */ 297#define FS_BSDFFS 7 /* 4.2BSD fast file system */ 298#define FS_MSDOS 8 /* MSDOS file system */ 299#define FS_BSDLFS 9 /* 4.4BSD log-structured file system */ 300#define FS_OTHER 10 /* in use, but unknown/unsupported */ 301#define FS_HPFS 11 /* OS/2 high-performance file system */ 302#define FS_ISO9660 12 /* ISO 9660, normally CD-ROM */ 303#define FS_BOOT 13 /* partition contains bootstrap */ 304#define FS_ADOS 14 /* AmigaDOS fast file system */ 305#define FS_HFS 15 /* Macintosh HFS */ 306#define FS_ADFS 16 /* Acorn Disk Filing System */ 307#define FS_EXT2FS 17 /* ext2fs */ 308#define FS_CCD 18 /* ccd component */ 309#define FS_RAID 19 /* RAIDframe */ 310 311#ifdef DKTYPENAMES 312static char *fstypenames[] = { 313 "unused", 314 "swap", 315 "Version6", 316 "Version7", 317 "SystemV", 318 "4.1BSD", 319 "Eighth-Edition", 320 "4.2BSD", 321 "MSDOS", 322 "4.4LFS", 323 "unknown", 324 "HPFS", 325 "ISO9660", 326 "boot", 327 "ADOS", 328 "HFS", 329 "ADFS", 330 "ext2fs", 331 "ccd", 332 "RAID", 333 NULL 334}; 335#define FSMAXTYPES (sizeof(fstypenames) / sizeof(fstypenames[0]) - 1) 336#endif 337 338/* 339 * flags shared by various drives: 340 */ 341#define D_REMOVABLE 0x01 /* removable media */ 342#define D_ECC 0x02 /* supports ECC */ 343#define D_BADSECT 0x04 /* supports bad sector forw. */ 344#define D_RAMDISK 0x08 /* disk emulator */ 345#define D_CHAIN 0x10 /* can do back-back transfers */ 346 347/* 348 * Drive data for SMD. 349 */ 350 351#define d_smdflags d_drivedata[0] 352#define D_SSE 0x1 /* supports skip sectoring */ 353#define d_mindist d_drivedata[1] 354#define d_maxdist d_drivedata[2] 355#define d_sdist d_drivedata[3] 356 357/* 358 * Drive data for ST506. 359 */ 360#define d_precompcyl d_drivedata[0] 361#define d_gap3 d_drivedata[1] /* used only when formatting */ 362 363/* 364 * Drive data for SCSI. 365 */ 366#define d_blind d_drivedata[0] 367 368#ifndef LOCORE 369/* 370 * Structure used to perform a format 371 * or other raw operation, returning data 372 * and/or register values. 373 * Register identification and format 374 * are device- and driver-dependent. 375 */ 376struct format_op { 377 char *df_buf; 378 int df_count; /* value-result */ 379 daddr_t df_startblk; 380 int df_reg[8]; /* result */ 381}; 382 383/* 384 * Structure used internally to retrieve 385 * information about a partition on a disk. 386 */ 387struct partinfo { 388 struct disklabel *disklab; 389 struct partition *part; 390}; 391 392/* 393 * Disk-specific ioctls. 394 */ 395/* get and set disklabel; DIOCGPART used internally */ 396#define DIOCGDINFO _IOR('d', 101, struct disklabel) /* get */ 397#define DIOCSDINFO _IOW('d', 102, struct disklabel) /* set */ 398#define DIOCWDINFO _IOW('d', 103, struct disklabel) /* set, update disk */ 399#define DIOCGPART _IOW('d', 104, struct partinfo) /* get partition */ 400 401/* do format operation, read or write */ 402#define DIOCRFORMAT _IOWR('d', 105, struct format_op) 403#define DIOCWFORMAT _IOWR('d', 106, struct format_op) 404 405#define DIOCSSTEP _IOW('d', 107, int) /* set step rate */ 406#define DIOCSRETRIES _IOW('d', 108, int) /* set # of retries */ 407#define DIOCWLABEL _IOW('d', 109, int) /* write en/disable label */ 408 409#define DIOCSBAD _IOW('d', 110, struct dkbad) /* set kernel dkbad */ 410#define DIOCEJECT _IO('d', 112) /* eject disk */ 411#define DIOCLOCK _IOW('d', 113, int) /* lock/unlock pack */ 412 413#define DIOCGPDINFO _IOR('d', 114, struct disklabel)/* get physical */ 414#define DIOCRLDINFO _IO('d', 115) /* reload disklabel */ 415 416#endif /* LOCORE */ 417.Ed 418.Sh SEE ALSO 419.Xr disktab 5 , 420.Xr disklabel 8 421