1 /* SPDX-License-Identifier: GPL-2.0+ */
3 * Copyright (c) International Business Machines Corp., 2006
5 * Authors: Artem Bityutskiy (Битюцкий Артём)
13 * This file defines the layout of UBI headers and all the other UBI on-flash
17 #ifndef __UBI_MEDIA_H__
18 #define __UBI_MEDIA_H__
20 #include <asm/byteorder.h>
22 /* The version of UBI images supported by this implementation */
25 /* The highest erase counter value supported by this implementation */
26 #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
28 /* The initial CRC32 value used when calculating CRC checksums */
29 #define UBI_CRC32_INIT 0xFFFFFFFFU
31 /* Erase counter header magic number (ASCII "UBI#") */
32 #define UBI_EC_HDR_MAGIC 0x55424923
33 /* Volume identifier header magic number (ASCII "UBI!") */
34 #define UBI_VID_HDR_MAGIC 0x55424921
37 * Volume type constants used in the volume identifier header.
39 * @UBI_VID_DYNAMIC: dynamic volume
40 * @UBI_VID_STATIC: static volume
48 * Volume flags used in the volume table record.
50 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
51 * @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
52 * open time. Should only be set on volumes that
53 * are used by upper layers doing this kind of
54 * check. Main use-case for this flag is
57 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
58 * table. UBI automatically re-sizes the volume which has this flag and makes
59 * the volume to be of largest possible size. This means that if after the
60 * initialization UBI finds out that there are available physical eraseblocks
61 * present on the device, it automatically appends all of them to the volume
62 * (the physical eraseblocks reserved for bad eraseblocks handling and other
63 * reserved physical eraseblocks are not taken). So, if there is a volume with
64 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
65 * eraseblocks will be zero after UBI is loaded, because all of them will be
66 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
67 * after the volume had been initialized.
69 * The auto-resize feature is useful for device production purposes. For
70 * example, different NAND flash chips may have different amount of initial bad
71 * eraseblocks, depending of particular chip instance. Manufacturers of NAND
72 * chips usually guarantee that the amount of initial bad eraseblocks does not
73 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
74 * flashed to the end devices in production, he does not know the exact amount
75 * of good physical eraseblocks the NAND chip on the device will have, but this
76 * number is required to calculate the volume sized and put them to the volume
77 * table of the UBI image. In this case, one of the volumes (e.g., the one
78 * which will store the root file system) is marked as "auto-resizable", and
79 * UBI will adjust its size on the first boot if needed.
81 * Note, first UBI reserves some amount of physical eraseblocks for bad
82 * eraseblock handling, and then re-sizes the volume, not vice-versa. This
83 * means that the pool of reserved physical eraseblocks will always be present.
86 UBI_VTBL_AUTORESIZE_FLG = 0x01,
87 UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02,
91 * Compatibility constants used by internal volumes.
93 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
95 * @UBI_COMPAT_RO: attach this device in read-only mode
96 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
97 * physical eraseblocks, don't allow the wear-leveling
98 * sub-system to move them
99 * @UBI_COMPAT_REJECT: reject this UBI image
102 UBI_COMPAT_DELETE = 1,
104 UBI_COMPAT_PRESERVE = 4,
105 UBI_COMPAT_REJECT = 5
108 /* Sizes of UBI headers */
109 #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr)
110 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
112 /* Sizes of UBI headers without the ending CRC */
113 #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32))
114 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
117 * struct ubi_ec_hdr - UBI erase counter header.
118 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
119 * @version: version of UBI implementation which is supposed to accept this
121 * @padding1: reserved for future, zeroes
122 * @ec: the erase counter
123 * @vid_hdr_offset: where the VID header starts
124 * @data_offset: where the user data start
125 * @image_seq: image sequence number
126 * @padding2: reserved for future, zeroes
127 * @hdr_crc: erase counter header CRC checksum
129 * The erase counter header takes 64 bytes and has a plenty of unused space for
130 * future usage. The unused fields are zeroed. The @version field is used to
131 * indicate the version of UBI implementation which is supposed to be able to
132 * work with this UBI image. If @version is greater than the current UBI
133 * version, the image is rejected. This may be useful in future if something
134 * is changed radically. This field is duplicated in the volume identifier
137 * The @vid_hdr_offset and @data_offset fields contain the offset of the the
138 * volume identifier header and user data, relative to the beginning of the
139 * physical eraseblock. These values have to be the same for all physical
142 * The @image_seq field is used to validate a UBI image that has been prepared
143 * for a UBI device. The @image_seq value can be any value, but it must be the
144 * same on all eraseblocks. UBI will ensure that all new erase counter headers
145 * also contain this value, and will check the value when attaching the flash.
146 * One way to make use of @image_seq is to increase its value by one every time
147 * an image is flashed over an existing image, then, if the flashing does not
148 * complete, UBI will detect the error when attaching the media.
154 __be64 ec; /* Warning: the current limit is 31-bit anyway! */
155 __be32 vid_hdr_offset;
163 * struct ubi_vid_hdr - on-flash UBI volume identifier header.
164 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
165 * @version: UBI implementation version which is supposed to accept this UBI
166 * image (%UBI_VERSION)
167 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
168 * @copy_flag: if this logical eraseblock was copied from another physical
169 * eraseblock (for wear-leveling reasons)
170 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
171 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
172 * @vol_id: ID of this volume
173 * @lnum: logical eraseblock number
174 * @padding1: reserved for future, zeroes
175 * @data_size: how many bytes of data this logical eraseblock contains
176 * @used_ebs: total number of used logical eraseblocks in this volume
177 * @data_pad: how many bytes at the end of this physical eraseblock are not
179 * @data_crc: CRC checksum of the data stored in this logical eraseblock
180 * @padding2: reserved for future, zeroes
181 * @sqnum: sequence number
182 * @padding3: reserved for future, zeroes
183 * @hdr_crc: volume identifier header CRC checksum
185 * The @sqnum is the value of the global sequence counter at the time when this
186 * VID header was created. The global sequence counter is incremented each time
187 * UBI writes a new VID header to the flash, i.e. when it maps a logical
188 * eraseblock to a new physical eraseblock. The global sequence counter is an
189 * unsigned 64-bit integer and we assume it never overflows. The @sqnum
190 * (sequence number) is used to distinguish between older and newer versions of
191 * logical eraseblocks.
193 * There are 2 situations when there may be more than one physical eraseblock
194 * corresponding to the same logical eraseblock, i.e., having the same @vol_id
195 * and @lnum values in the volume identifier header. Suppose we have a logical
196 * eraseblock L and it is mapped to the physical eraseblock P.
198 * 1. Because UBI may erase physical eraseblocks asynchronously, the following
199 * situation is possible: L is asynchronously erased, so P is scheduled for
200 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
201 * so P1 is written to, then an unclean reboot happens. Result - there are 2
202 * physical eraseblocks P and P1 corresponding to the same logical eraseblock
203 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
206 * 2. From time to time UBI moves logical eraseblocks to other physical
207 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
208 * to P1, and an unclean reboot happens before P is physically erased, there
209 * are two physical eraseblocks P and P1 corresponding to L and UBI has to
210 * select one of them when the flash is attached. The @sqnum field says which
211 * PEB is the original (obviously P will have lower @sqnum) and the copy. But
212 * it is not enough to select the physical eraseblock with the higher sequence
213 * number, because the unclean reboot could have happen in the middle of the
214 * copying process, so the data in P is corrupted. It is also not enough to
215 * just select the physical eraseblock with lower sequence number, because the
216 * data there may be old (consider a case if more data was added to P1 after
217 * the copying). Moreover, the unclean reboot may happen when the erasure of P
218 * was just started, so it result in unstable P, which is "mostly" OK, but
219 * still has unstable bits.
221 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
222 * copy. UBI also calculates data CRC when the data is moved and stores it at
223 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
224 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
225 * examined. If it is cleared, the situation* is simple and the newer one is
226 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
227 * checksum is correct, this physical eraseblock is selected (P1). Otherwise
228 * the older one (P) is selected.
230 * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
231 * Internal volumes are not seen from outside and are used for various internal
232 * UBI purposes. In this implementation there is only one internal volume - the
233 * layout volume. Internal volumes are the main mechanism of UBI extensions.
234 * For example, in future one may introduce a journal internal volume. Internal
235 * volumes have their own reserved range of IDs.
237 * The @compat field is only used for internal volumes and contains the "degree
238 * of their compatibility". It is always zero for user volumes. This field
239 * provides a mechanism to introduce UBI extensions and to be still compatible
240 * with older UBI binaries. For example, if someone introduced a journal in
241 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
242 * journal volume. And in this case, older UBI binaries, which know nothing
243 * about the journal volume, would just delete this volume and work perfectly
244 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
245 * - it just ignores the Ext3fs journal.
247 * The @data_crc field contains the CRC checksum of the contents of the logical
248 * eraseblock if this is a static volume. In case of dynamic volumes, it does
249 * not contain the CRC checksum as a rule. The only exception is when the
250 * data of the physical eraseblock was moved by the wear-leveling sub-system,
251 * then the wear-leveling sub-system calculates the data CRC and stores it in
252 * the @data_crc field. And of course, the @copy_flag is %in this case.
254 * The @data_size field is used only for static volumes because UBI has to know
255 * how many bytes of data are stored in this eraseblock. For dynamic volumes,
256 * this field usually contains zero. The only exception is when the data of the
257 * physical eraseblock was moved to another physical eraseblock for
258 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
259 * contents and uses both @data_crc and @data_size fields. In this case, the
260 * @data_size field contains data size.
262 * The @used_ebs field is used only for static volumes and indicates how many
263 * eraseblocks the data of the volume takes. For dynamic volumes this field is
264 * not used and always contains zero.
266 * The @data_pad is calculated when volumes are created using the alignment
267 * parameter. So, effectively, the @data_pad field reduces the size of logical
268 * eraseblocks of this volume. This is very handy when one uses block-oriented
269 * software (say, cramfs) on top of the UBI volume.
290 /* Internal UBI volumes count */
291 #define UBI_INT_VOL_COUNT 1
294 * Starting ID of internal volumes: 0x7fffefff.
295 * There is reserved room for 4096 internal volumes.
297 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
299 /* The layout volume contains the volume table */
301 #define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START
302 #define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC
303 #define UBI_LAYOUT_VOLUME_ALIGN 1
304 #define UBI_LAYOUT_VOLUME_EBS 2
305 #define UBI_LAYOUT_VOLUME_NAME "layout volume"
306 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
308 /* The maximum number of volumes per one UBI device */
309 #define UBI_MAX_VOLUMES 128
311 /* The maximum volume name length */
312 #define UBI_VOL_NAME_MAX 127
314 /* Size of the volume table record */
315 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
317 /* Size of the volume table record without the ending CRC */
318 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
321 * struct ubi_vtbl_record - a record in the volume table.
322 * @reserved_pebs: how many physical eraseblocks are reserved for this volume
323 * @alignment: volume alignment
324 * @data_pad: how many bytes are unused at the end of the each physical
325 * eraseblock to satisfy the requested alignment
326 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
327 * @upd_marker: if volume update was started but not finished
328 * @name_len: volume name length
329 * @name: the volume name
330 * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
331 * @padding: reserved, zeroes
332 * @crc: a CRC32 checksum of the record
334 * The volume table records are stored in the volume table, which is stored in
335 * the layout volume. The layout volume consists of 2 logical eraseblock, each
336 * of which contains a copy of the volume table (i.e., the volume table is
337 * duplicated). The volume table is an array of &struct ubi_vtbl_record
338 * objects indexed by the volume ID.
340 * If the size of the logical eraseblock is large enough to fit
341 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
342 * records. Otherwise, it contains as many records as it can fit (i.e., size of
343 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
345 * The @upd_marker flag is used to implement volume update. It is set to %1
346 * before update and set to %0 after the update. So if the update operation was
347 * interrupted, UBI knows that the volume is corrupted.
349 * The @alignment field is specified when the volume is created and cannot be
350 * later changed. It may be useful, for example, when a block-oriented file
351 * system works on top of UBI. The @data_pad field is calculated using the
352 * logical eraseblock size and @alignment. The alignment must be multiple to the
353 * minimal flash I/O unit. If @alignment is 1, all the available space of
354 * the physical eraseblocks is used.
356 * Empty records contain all zeroes and the CRC checksum of those zeroes.
358 struct ubi_vtbl_record {
359 __be32 reserved_pebs;
366 __u8 name[UBI_VOL_NAME_MAX+1];
368 char name[UBI_VOL_NAME_MAX+1];
375 /* UBI fastmap on-flash data structures */
377 #define UBI_FM_SB_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 1)
378 #define UBI_FM_DATA_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 2)
380 /* fastmap on-flash data structure format version */
381 #define UBI_FM_FMT_VERSION 1
383 #define UBI_FM_SB_MAGIC 0x7B11D69F
384 #define UBI_FM_HDR_MAGIC 0xD4B82EF7
385 #define UBI_FM_VHDR_MAGIC 0xFA370ED1
386 #define UBI_FM_POOL_MAGIC 0x67AF4D08
387 #define UBI_FM_EBA_MAGIC 0xf0c040a8
389 /* A fastmap supber block can be located between PEB 0 and
390 * UBI_FM_MAX_START */
391 #define UBI_FM_MAX_START 64
393 /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
394 #define UBI_FM_MAX_BLOCKS 32
396 /* 5% of the total number of PEBs have to be scanned while attaching
398 * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
399 * UBI_FM_MAX_POOL_SIZE */
400 #define UBI_FM_MIN_POOL_SIZE 8
401 #define UBI_FM_MAX_POOL_SIZE 256
404 * struct ubi_fm_sb - UBI fastmap super block
405 * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
406 * @version: format version of this fastmap
407 * @data_crc: CRC over the fastmap data
408 * @used_blocks: number of PEBs used by this fastmap
409 * @block_loc: an array containing the location of all PEBs of the fastmap
410 * @block_ec: the erase counter of each used PEB
411 * @sqnum: highest sequence number value at the time while taking the fastmap
420 __be32 block_loc[UBI_FM_MAX_BLOCKS];
421 __be32 block_ec[UBI_FM_MAX_BLOCKS];
427 * struct ubi_fm_hdr - header of the fastmap data set
428 * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
429 * @free_peb_count: number of free PEBs known by this fastmap
430 * @used_peb_count: number of used PEBs known by this fastmap
431 * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
432 * @bad_peb_count: number of bad PEBs known by this fastmap
433 * @erase_peb_count: number of bad PEBs which have to be erased
434 * @vol_count: number of UBI volumes known by this fastmap
438 __be32 free_peb_count;
439 __be32 used_peb_count;
440 __be32 scrub_peb_count;
441 __be32 bad_peb_count;
442 __be32 erase_peb_count;
447 /* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
450 * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
451 * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
452 * @size: current pool size
453 * @max_size: maximal pool size
454 * @pebs: an array containing the location of all PEBs in this pool
456 struct ubi_fm_scan_pool {
460 __be32 pebs[UBI_FM_MAX_POOL_SIZE];
464 /* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
467 * struct ubi_fm_ec - stores the erase counter of a PEB
469 * @ec: ec of this PEB
477 * struct ubi_fm_volhdr - Fastmap volume header
478 * it identifies the start of an eba table
479 * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
480 * @vol_id: volume id of the fastmapped volume
481 * @vol_type: type of the fastmapped volume
482 * @data_pad: data_pad value of the fastmapped volume
483 * @used_ebs: number of used LEBs within this volume
484 * @last_eb_bytes: number of bytes used in the last LEB
486 struct ubi_fm_volhdr {
493 __be32 last_eb_bytes;
497 /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
500 * struct ubi_fm_eba - denotes an association beween a PEB and LEB
501 * @magic: EBA table magic number
502 * @reserved_pebs: number of table entries
503 * @pnum: PEB number of LEB (LEB is the index)
507 __be32 reserved_pebs;
510 #endif /* !__UBI_MEDIA_H__ */