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1 .\" $NetBSD: disklabel.5,v 1.26 2005/09/21 14:51:20 tsutsui Exp $
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33 .\" @(#)disklabel.5.5 8.1 (Berkeley) 6/5/93
34 .\"
35 .Dd February 24, 2006
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
44 Each disk or disk pack on a system may contain a disk label
45 which provides detailed information
46 about the geometry of the disk and the partitions into which the disk
47 is divided.
48 It should be initialized when the disk is formatted,
49 and may be changed later with the
50 .Xr disklabel 8
51 program.
52 This information is used by the system disk driver and by the bootstrap
53 program to determine how to program the drive
54 and where to find the file systems on the disk partitions.
55 Additional information is used by the file system in order
56 to use the disk most efficiently and to locate important file system information.
57 The description of each partition contains an identifier for the partition
58 type (standard file system, swap area, etc.).
59 The file system updates the in-core copy of the label if it contains
60 incomplete information about the file system.
61 .Pp
62 The label is located in the sector number returned by the
63 .Xr getlabelsector 3
64 function, usually sector 0 where it may be found
65 without any information about the disk geometry.
66 It is at an offset (specified by the
67 .Xr getlabeloffset 3
68 function)
69 from the beginning of the sector, to allow room for the initial bootstrap.
70 The disk sector containing the label is normally made read-only
71 so that it is not accidentally overwritten by pack-to-pack copies
72 or swap operations;
73 the
74 .Dv DIOCWLABEL
75 .Xr ioctl 2 ,
76 which is done as needed by the
77 .Xr disklabel 8
78 program.
79 .Pp
80 A copy of the in-core label for a disk can be obtained with the
81 .Dv DIOCGDINFO
82 .Xr ioctl 2 ;
83 this works with a file descriptor for a block or character (``raw'') device
84 for any partition of the disk.
85 The in-core copy of the label is set by the
86 .Dv DIOCSDINFO
87 .Xr ioctl 2 .
88 The offset of a partition cannot generally be changed while it is open,
89 nor can it be made smaller while it is open.
90 One exception is that any change is allowed if no label was found
91 on the disk, and the driver was able to construct only a skeletal label
92 without partition information.
93 Finally, the
94 .Dv DIOCWDINFO
95 .Xr ioctl 2
96 operation sets the in-core label and then updates the on-disk label;
97 there must be an existing label on the disk for this operation to succeed.
98 Thus, the initial label for a disk or disk pack must be installed
99 by writing to the raw disk.
100 All of these operations are normally done using
101 .Xr disklabel 8 .
102 .Pp
103 The format of the disk label, as specified in
104 .Pa sys/disklabel.h ,
105 is
106 .Bd -literal
107 /*
108 * Disk description table, see disktab(5)
109 */
110 #define _PATH_DISKTAB "/etc/disktab"
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 \*[Lt]machine/disklabel.h\*[Gt]
121 /*
122 * The absolute maximum number of disk partitions allowed.
123 * This is the maximum value of MAXPARTITIONS for which 'struct disklabel'
124 * is \*[Le] DEV_BSIZE bytes long. If MAXPARTITIONS is greater than this, beware.
125 */
126 #define MAXMAXPARTITIONS 22
127 #if MAXPARTITIONS \*[Gt] MAXMAXPARTITIONS
128 #warning beware: MAXPARTITIONS bigger than MAXMAXPARTITIONS
129 #endif
132 #define DISKMAGIC ((u_int32_t)0x82564557) /* The disk magic number */
134 #ifndef _LOCORE
135 struct 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" */
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
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 */
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 */
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 */
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 */
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 */
264 #ifdef DKTYPENAMES
265 static 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
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 */
321 #ifdef FSTYPENAMES
322 static 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
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 */
361 /*
362 * Drive data for SMD.
363 */
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]
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 */
377 /*
378 * Drive data for SCSI.
379 */
380 #define d_blind d_drivedata[0]
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 */
388 struct format_op {
389 char *df_buf;
390 int df_count; /* value-result */
391 daddr_t df_startblk;
392 int df_reg[8]; /* result */
393 };
395 /*
396 * Structure used internally to retrieve information about a partition
397 * on a disk.
398 */
399 struct partinfo {
400 struct disklabel *disklab;
401 struct partition *part;
402 };
403 .Ed
404 .Pp
405 Disk specific ioctls are defined in
406 .Pa sys/dkio.h .
407 .Pp
408 .Bd -literal
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 */
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)
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 */
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 */
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