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1.1 root 1: .\" Copyright (c) 1987 Regents of the University of California.
2: .\" All rights reserved.
3: .\"
4: .\" This code is derived from software contributed to Berkeley by
5: .\" Symmetric Computer Systems.
6: .\"
7: .\" Redistribution and use in source and binary forms are permitted
8: .\" provided that the above copyright notice and this paragraph are
9: .\" duplicated in all such forms and that any documentation,
10: .\" advertising materials, and other materials related to such
11: .\" distribution and use acknowledge that the software was developed
12: .\" by the University of California, Berkeley. The name of the
13: .\" University may not be used to endorse or promote products derived
14: .\" from this software without specific prior written permission.
15: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16: .\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17: .\" WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18: .\"
19: .\" @(#)disklabel.5 6.4 (Berkeley) 7/9/88
20: .\"
21: .TH DISKLABEL 5 "July 9, 1988"
22: .UC 7
23: .SH NAME
24: disklabel \- disk pack label
25: .SH SYNOPSIS
26: .B #include <sys/disklabel.h>
27: .SH DESCRIPTION
28: Each disk or disk pack on a system may contain a disk label
29: which provides detailed information
30: about the geometry of the disk and the partitions into which the disk
31: is divided.
32: It should be initialized when the disk is formatted,
33: and may be changed later with the
34: .IR disklabel (8)
35: program.
36: This information is used by the system disk driver and by the bootstrap
37: program to determine how to program the drive
38: and where to find the filesystems on the disk partitions.
39: Additional information is used by the filesystem in order
40: to use the disk most efficiently and to locate important filesystem information.
41: The description of each partition contains an identifier for the partition
42: type (standard filesystem, swap area, etc.).
43: The filesystem updates the in-core copy of the label if it contains
44: incomplete information about the filesystem.
45: .PP
46: The label is located in sector number
47: .I LABELSECTOR
48: of the drive, usually sector 0 where it may be found
49: without any information about the disk geometry.
50: It is at an offset
51: .I LABELOFFSET
52: from the beginning of the sector, to allow room for the initial bootstrap.
53: The disk sector containing the label is normally made read-only
54: so that it is not accidentally overwritten by pack-to-pack copies
55: or swap operations;
56: the DIOCWLABEL
57: .IR ioctl ,
58: which is done as needed by the
59: .IR disklabel (8)
60: program.
61: .PP
62: A copy of the in-core label for a disk can be obtained with the DIOCGDINFO
63: .IR ioctl ;
64: this works with a file descriptor for a block or character (``raw'') device
65: for any partition of the disk.
66: The in-core copy of the label is set by the DIOCSDINFO
67: .IR ioctl .
68: The offset of a partition cannot generally be changed while it is open,
69: nor can it be made smaller while it is open.
70: One exception is that any change is allowed if no label was found
71: on the disk, and the driver was able to construct only a skeletal label
72: without partition information.
73: Finally, the DIOCWDINFO
74: .I ioctl
75: operation sets the in-core label and then updates the on-disk label;
76: there must be an existing label on the disk for this operation to succeed.
77: Thus, the initial label for a disk or disk pack must be installed
78: by writing to the raw disk.
79: All of these operations are normally done using
80: .IR disklabel (8).
81: .PP
82: The format of the disk label, as specified in
83: .RI < sys/disklabel.h >,
84: is
85: .nf
86: .DT
87: /*
88: * Disk description table, see disktab(5)
89: */
90: #define DISKTAB "/etc/disktab"
91:
92: /*
93: * Each disk has a label which includes information about the hardware
94: * disk geometry, filesystem partitions, and drive specific information.
95: * The label is in block 0 or 1, possibly offset from the beginning
96: * to leave room for a bootstrap, etc.
97: */
98: .ta \w'#define 'u +\w'MAXPARTITIONS 'u +\w'((u_long) 0x82564557) 'u
99: #define LABELSECTOR 0 /* sector containing label */
100: #define LABELOFFSET 64 /* offset of label in sector */
101: #define DISKMAGIC ((u_long) 0x82564557) /* The disk magic number */
102: #ifndef MAXPARTITIONS
103: #define MAXPARTITIONS 8
104: #endif
105:
106:
107: .ta \w'struct 'u +\w'u_long 'u +\w'd_packname[16] 'u
108: #ifndef LOCORE
109: struct disklabel {
110: u_long d_magic; /* the magic number */
111: short d_type; /* drive type */
112: short d_subtype; /* controller/d_type specific */
113: char d_typename[16]; /* type name, e.g. "eagle" */
114: /*
115: * d_packname contains the pack identifier and is returned when
116: * the disklabel is read off the disk or in-core copy.
117: * d_boot0 and d_boot1 are the (optional) names of the
118: * primary (block 0) and secondary (block 1-15) bootstraps
119: * as found in /usr/mdec. These are returned when using
120: * getdiskbyname(3) to retrieve the values from /etc/disktab.
121: */
122: #if defined(KERNEL) || defined(STANDALONE)
123: char d_packname[16]; /* pack identifier */
124: #else
125: .ta \w'struct 'u +\w'struct 'u +\w'struct { 'u +\w'un_d_packname[16] 'u
126: union {
127: char un_d_packname[16]; /* pack identifier */
128: struct {
129: char *un_d_boot0; /* primary bootstrap name */
130: char *un_d_boot1; /* secondary bootstrap name */
131: } un_b;
132: } d_un;
133: .ta \w'#define 'u +\w'd_packname 'u
134: #define d_packname d_un.un_d_packname
135: #define d_boot0 d_un.un_b.un_d_boot0
136: #define d_boot1 d_un.un_b.un_d_boot1
137: #endif /* ! KERNEL or STANDALONE */
138: .ta \w'struct 'u +\w'u_short 'u +\w'd_d_drivedata[NDDATA] 'u
139: /* disk geometry: */
140: u_long d_secsize; /* # of bytes per sector */
141: u_long d_nsectors; /* # of data sectors per track */
142: u_long d_ntracks; /* # of tracks per cylinder */
143: u_long d_ncylinders; /* # of data cylinders per unit */
144: u_long d_secpercyl; /* # of data sectors per cylinder */
145: u_long d_secperunit; /* # of data sectors per unit */
146: /*
147: * Spares (bad sector replacements) below
148: * are not counted in d_nsectors or d_secpercyl.
149: * Spare sectors are assumed to be physical sectors
150: * which occupy space at the end of each track and/or cylinder.
151: */
152: u_short d_sparespertrack; /* # of spare sectors per track */
153: u_short d_sparespercyl; /* # of spare sectors per cylinder */
154: /*
155: * Alternate cylinders include maintenance, replacement,
156: * configuration description areas, etc.
157: */
158: u_long d_acylinders; /* # of alt. cylinders per unit */
159:
160: /* hardware characteristics: */
161: /*
162: * d_interleave, d_trackskew and d_cylskew describe perturbations
163: * in the media format used to compensate for a slow controller.
164: * Interleave is physical sector interleave, set up by the formatter
165: * or controller when formatting. When interleaving is in use,
166: * logically adjacent sectors are not physically contiguous,
167: * but instead are separated by some number of sectors.
168: * It is specified as the ratio of physical sectors traversed
169: * per logical sector. Thus an interleave of 1:1 implies contiguous
170: * layout, while 2:1 implies that logical sector 0 is separated
171: * by one sector from logical sector 1.
172: * d_trackskew is the offset of sector 0 on track N
173: * relative to sector 0 on track N-1 on the same cylinder.
174: * Finally, d_cylskew is the offset of sector 0 on cylinder N
175: * relative to sector 0 on cylinder N-1.
176: */
177: u_short d_rpm; /* rotational speed */
178: u_short d_interleave; /* hardware sector interleave */
179: u_short d_trackskew; /* sector 0 skew, per track */
180: u_short d_cylskew; /* sector 0 skew, per cylinder */
181: u_long d_headswitch; /* head switch time, usec */
182: u_long d_trkseek; /* track-to-track seek, usec */
183: u_long d_flags; /* generic flags */
184: #define NDDATA 5
185: u_long d_drivedata[NDDATA]; /* drive-type specific information */
186: #define NSPARE 5
187: u_long d_spare[NSPARE]; /* reserved for future use */
188: u_long d_magic2; /* the magic number (again) */
189: u_short d_checksum; /* xor of data incl. partitions */
190:
191: /* filesystem and partition information: */
192: u_short d_npartitions; /* number of partitions in following */
193: u_long d_bbsize; /* size of boot area at sn0, bytes */
194: u_long d_sbsize; /* max size of fs superblock, bytes */
195: struct partition { /* the partition table */
196: .ta \w'struct 'u +\w'struct 'u +\w'u_short 'u +\w'd_d_drivedata[NDDATA] 'u
197: u_long p_size; /* number of sectors in partition */
198: u_long p_offset; /* starting sector */
199: u_long p_fsize; /* filesystem basic fragment size */
200: u_char p_fstype; /* filesystem type, see below */
201: u_char p_frag; /* filesystem fragments per block */
202: u_short p_cpg; /* filesystem cylinders per group */
203: .ta \w'struct 'u +\w'u_short 'u +\w'd_d_drivedata[NDDATA] 'u
204: } d_partitions[MAXPARTITIONS]; /* actually may be more */
205: };
206:
207: /* d_type values: */
208: .ta \w'#define 'u +\w'DTYPE_FLOPPY 'u +\w'0x10 'u
209: #define DTYPE_SMD 1 /* SMD, XSMD; VAX hp/up */
210: #define DTYPE_MSCP 2 /* MSCP */
211: #define DTYPE_DEC 3 /* other DEC (rk, rl) */
212: #define DTYPE_SCSI 4 /* SCSI */
213: #define DTYPE_ESDI 5 /* ESDI interface */
214: #define DTYPE_ST506 6 /* ST506 etc. */
215: #define DTYPE_FLOPPY 10 /* floppy */
216:
217: #ifdef DKTYPENAMES
218: static char *dktypenames[] = {
219: "unknown",
220: "SMD",
221: "MSCP",
222: "old DEC",
223: "SCSI",
224: "ESDI",
225: "type 6",
226: "type 7",
227: "type 8",
228: "type 9",
229: "floppy",
230: 0
231: };
232: #define DKMAXTYPES (sizeof(dktypenames) / sizeof(dktypenames[0]) - 1)
233: #endif
234:
235: /*
236: * Filesystem type and version.
237: * Used to interpret other filesystem-specific
238: * per-partition information.
239: */
240: #define FS_UNUSED 0 /* unused */
241: #define FS_SWAP 1 /* swap */
242: #define FS_V6 2 /* Sixth Edition */
243: #define FS_V7 3 /* Seventh Edition */
244: #define FS_SYSV 4 /* System V */
245: #define FS_V71K 5 /* V7 with 1K blocks (4.1, 2.9) */
246: #define FS_V8 6 /* Eighth Edition, 4K blocks */
247: #define FS_BSDFFS 7 /* 4.2BSD fast file system */
248:
249: #ifdef DKTYPENAMES
250: static char *fstypenames[] = {
251: "unused",
252: "swap",
253: "Version 6",
254: "Version 7",
255: "System V",
256: "4.1BSD",
257: "Eighth Edition",
258: "4.2BSD",
259: 0
260: };
261: #define FSMAXTYPES (sizeof(fstypenames) / sizeof(fstypenames[0]) - 1)
262: #endif
263:
264: /*
265: * flags shared by various drives:
266: */
267: #define D_REMOVABLE 0x01 /* removable media */
268: #define D_ECC 0x02 /* supports ECC */
269: #define D_BADSECT 0x04 /* supports bad sector forw. */
270: #define D_RAMDISK 0x08 /* disk emulator */
271: #define D_CHAIN 0x10 /* can do back-back transfers */
272:
273: /*
274: * Drive data for SMD.
275: */
276: .ta \w'#define 'u +\w'DTYPE_FLOPPY 'u +\w'd_drivedata[1] 'u
277: #define d_smdflags d_drivedata[0]
278: #define D_SSE 0x1 /* supports skip sectoring */
279: #define d_mindist d_drivedata[1]
280: #define d_maxdist d_drivedata[2]
281: #define d_sdist d_drivedata[3]
282:
283: /*
284: * Drive data for ST506.
285: */
286: #define d_precompcyl d_drivedata[0]
287: #define d_gap3 d_drivedata[1] /* used only when formatting */
288:
289: #ifndef LOCORE
290: /*
291: * Structure used to perform a format
292: * or other raw operation, returning data
293: * and/or register values.
294: * Register identification and format
295: * are device- and driver-dependent.
296: */
297: .ta \w'struct 'u +\w'daddr_t 'u +\w'df_startblk 'u
298: struct format_op {
299: char *df_buf;
300: int df_count; /* value-result */
301: daddr_t df_startblk;
302: int df_reg[8]; /* result */
303: };
304:
305: /*
306: * Structure used internally to retrieve
307: * information about a partition on a disk.
308: */
309: struct partinfo {
310: struct disklabel *disklab;
311: struct partition *part;
312: };
313:
314: /*
315: * Disk-specific ioctls.
316: */
317: /* get and set disklabel; DIOCGPART used internally */
318: .ta \w'#define 'u +\w'DIOCSRETRIES 'u +\w'_IOW( d , 103, struct disklabel) 'u
319: #define DIOCGDINFO _IOR('d', 101, struct disklabel) /* get */
320: #define DIOCSDINFO _IOW('d', 102, struct disklabel) /* set */
321: #define DIOCWDINFO _IOW('d', 103, struct disklabel) /* set, update disk */
322: #define DIOCGPART _IOW('d', 104, struct partinfo) /* get partition */
323:
324: /* do format operation, read or write */
325: #define DIOCRFORMAT _IOWR('d', 105, struct format_op)
326: #define DIOCWFORMAT _IOWR('d', 106, struct format_op)
327:
328: #define DIOCSSTEP _IOW('d', 107, int) /* set step rate */
329: #define DIOCSRETRIES _IOW('d', 108, int) /* set # of retries */
330: #define DIOCWLABEL _IOW('d', 109, int) /* write en/disable label */
331:
332: #define DIOCSBAD _IOW('d', 110, struct dkbad) /* set kernel dkbad */
333:
334: #endif LOCORE
335: .SH "SEE ALSO"
336: disktab(5), disklabel(8)
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