1 /* 2 * Copyright (c) International Business Machines Corp., 2006 3 * 4 * SPDX-License-Identifier: GPL-2.0+ 5 * 6 * Authors: Artem Bityutskiy (Битюцкий Артём) 7 * Thomas Gleixner 8 * Frank Haverkamp 9 * Oliver Lohmann 10 * Andreas Arnez 11 */ 12 13 /* 14 * This file defines the layout of UBI headers and all the other UBI on-flash 15 * data structures. 16 */ 17 18 #ifndef __UBI_MEDIA_H__ 19 #define __UBI_MEDIA_H__ 20 21 #include <asm/byteorder.h> 22 23 /* The version of UBI images supported by this implementation */ 24 #define UBI_VERSION 1 25 26 /* The highest erase counter value supported by this implementation */ 27 #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF 28 29 /* The initial CRC32 value used when calculating CRC checksums */ 30 #define UBI_CRC32_INIT 0xFFFFFFFFU 31 32 /* Erase counter header magic number (ASCII "UBI#") */ 33 #define UBI_EC_HDR_MAGIC 0x55424923 34 /* Volume identifier header magic number (ASCII "UBI!") */ 35 #define UBI_VID_HDR_MAGIC 0x55424921 36 37 /* 38 * Volume type constants used in the volume identifier header. 39 * 40 * @UBI_VID_DYNAMIC: dynamic volume 41 * @UBI_VID_STATIC: static volume 42 */ 43 enum { 44 UBI_VID_DYNAMIC = 1, 45 UBI_VID_STATIC = 2 46 }; 47 48 /* 49 * Volume flags used in the volume table record. 50 * 51 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume 52 * 53 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume 54 * table. UBI automatically re-sizes the volume which has this flag and makes 55 * the volume to be of largest possible size. This means that if after the 56 * initialization UBI finds out that there are available physical eraseblocks 57 * present on the device, it automatically appends all of them to the volume 58 * (the physical eraseblocks reserved for bad eraseblocks handling and other 59 * reserved physical eraseblocks are not taken). So, if there is a volume with 60 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical 61 * eraseblocks will be zero after UBI is loaded, because all of them will be 62 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared 63 * after the volume had been initialized. 64 * 65 * The auto-resize feature is useful for device production purposes. For 66 * example, different NAND flash chips may have different amount of initial bad 67 * eraseblocks, depending of particular chip instance. Manufacturers of NAND 68 * chips usually guarantee that the amount of initial bad eraseblocks does not 69 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be 70 * flashed to the end devices in production, he does not know the exact amount 71 * of good physical eraseblocks the NAND chip on the device will have, but this 72 * number is required to calculate the volume sized and put them to the volume 73 * table of the UBI image. In this case, one of the volumes (e.g., the one 74 * which will store the root file system) is marked as "auto-resizable", and 75 * UBI will adjust its size on the first boot if needed. 76 * 77 * Note, first UBI reserves some amount of physical eraseblocks for bad 78 * eraseblock handling, and then re-sizes the volume, not vice-versa. This 79 * means that the pool of reserved physical eraseblocks will always be present. 80 */ 81 enum { 82 UBI_VTBL_AUTORESIZE_FLG = 0x01, 83 }; 84 85 /* 86 * Compatibility constants used by internal volumes. 87 * 88 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written 89 * to the flash 90 * @UBI_COMPAT_RO: attach this device in read-only mode 91 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its 92 * physical eraseblocks, don't allow the wear-leveling unit to move them 93 * @UBI_COMPAT_REJECT: reject this UBI image 94 */ 95 enum { 96 UBI_COMPAT_DELETE = 1, 97 UBI_COMPAT_RO = 2, 98 UBI_COMPAT_PRESERVE = 4, 99 UBI_COMPAT_REJECT = 5 100 }; 101 102 /* Sizes of UBI headers */ 103 #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr) 104 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr) 105 106 /* Sizes of UBI headers without the ending CRC */ 107 #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32)) 108 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32)) 109 110 /** 111 * struct ubi_ec_hdr - UBI erase counter header. 112 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC) 113 * @version: version of UBI implementation which is supposed to accept this 114 * UBI image 115 * @padding1: reserved for future, zeroes 116 * @ec: the erase counter 117 * @vid_hdr_offset: where the VID header starts 118 * @data_offset: where the user data start 119 * @padding2: reserved for future, zeroes 120 * @hdr_crc: erase counter header CRC checksum 121 * 122 * The erase counter header takes 64 bytes and has a plenty of unused space for 123 * future usage. The unused fields are zeroed. The @version field is used to 124 * indicate the version of UBI implementation which is supposed to be able to 125 * work with this UBI image. If @version is greater then the current UBI 126 * version, the image is rejected. This may be useful in future if something 127 * is changed radically. This field is duplicated in the volume identifier 128 * header. 129 * 130 * The @vid_hdr_offset and @data_offset fields contain the offset of the the 131 * volume identifier header and user data, relative to the beginning of the 132 * physical eraseblock. These values have to be the same for all physical 133 * eraseblocks. 134 */ 135 struct ubi_ec_hdr { 136 __be32 magic; 137 __u8 version; 138 __u8 padding1[3]; 139 __be64 ec; /* Warning: the current limit is 31-bit anyway! */ 140 __be32 vid_hdr_offset; 141 __be32 data_offset; 142 __u8 padding2[36]; 143 __be32 hdr_crc; 144 } __attribute__ ((packed)); 145 146 /** 147 * struct ubi_vid_hdr - on-flash UBI volume identifier header. 148 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC) 149 * @version: UBI implementation version which is supposed to accept this UBI 150 * image (%UBI_VERSION) 151 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC) 152 * @copy_flag: if this logical eraseblock was copied from another physical 153 * eraseblock (for wear-leveling reasons) 154 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE, 155 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT) 156 * @vol_id: ID of this volume 157 * @lnum: logical eraseblock number 158 * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be 159 * removed, kept only for not breaking older UBI users) 160 * @data_size: how many bytes of data this logical eraseblock contains 161 * @used_ebs: total number of used logical eraseblocks in this volume 162 * @data_pad: how many bytes at the end of this physical eraseblock are not 163 * used 164 * @data_crc: CRC checksum of the data stored in this logical eraseblock 165 * @padding1: reserved for future, zeroes 166 * @sqnum: sequence number 167 * @padding2: reserved for future, zeroes 168 * @hdr_crc: volume identifier header CRC checksum 169 * 170 * The @sqnum is the value of the global sequence counter at the time when this 171 * VID header was created. The global sequence counter is incremented each time 172 * UBI writes a new VID header to the flash, i.e. when it maps a logical 173 * eraseblock to a new physical eraseblock. The global sequence counter is an 174 * unsigned 64-bit integer and we assume it never overflows. The @sqnum 175 * (sequence number) is used to distinguish between older and newer versions of 176 * logical eraseblocks. 177 * 178 * There are 2 situations when there may be more then one physical eraseblock 179 * corresponding to the same logical eraseblock, i.e., having the same @vol_id 180 * and @lnum values in the volume identifier header. Suppose we have a logical 181 * eraseblock L and it is mapped to the physical eraseblock P. 182 * 183 * 1. Because UBI may erase physical eraseblocks asynchronously, the following 184 * situation is possible: L is asynchronously erased, so P is scheduled for 185 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1, 186 * so P1 is written to, then an unclean reboot happens. Result - there are 2 187 * physical eraseblocks P and P1 corresponding to the same logical eraseblock 188 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the 189 * flash. 190 * 191 * 2. From time to time UBI moves logical eraseblocks to other physical 192 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P 193 * to P1, and an unclean reboot happens before P is physically erased, there 194 * are two physical eraseblocks P and P1 corresponding to L and UBI has to 195 * select one of them when the flash is attached. The @sqnum field says which 196 * PEB is the original (obviously P will have lower @sqnum) and the copy. But 197 * it is not enough to select the physical eraseblock with the higher sequence 198 * number, because the unclean reboot could have happen in the middle of the 199 * copying process, so the data in P is corrupted. It is also not enough to 200 * just select the physical eraseblock with lower sequence number, because the 201 * data there may be old (consider a case if more data was added to P1 after 202 * the copying). Moreover, the unclean reboot may happen when the erasure of P 203 * was just started, so it result in unstable P, which is "mostly" OK, but 204 * still has unstable bits. 205 * 206 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a 207 * copy. UBI also calculates data CRC when the data is moved and stores it at 208 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical 209 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is 210 * examined. If it is cleared, the situation* is simple and the newer one is 211 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC 212 * checksum is correct, this physical eraseblock is selected (P1). Otherwise 213 * the older one (P) is selected. 214 * 215 * Note, there is an obsolete @leb_ver field which was used instead of @sqnum 216 * in the past. But it is not used anymore and we keep it in order to be able 217 * to deal with old UBI images. It will be removed at some point. 218 * 219 * There are 2 sorts of volumes in UBI: user volumes and internal volumes. 220 * Internal volumes are not seen from outside and are used for various internal 221 * UBI purposes. In this implementation there is only one internal volume - the 222 * layout volume. Internal volumes are the main mechanism of UBI extensions. 223 * For example, in future one may introduce a journal internal volume. Internal 224 * volumes have their own reserved range of IDs. 225 * 226 * The @compat field is only used for internal volumes and contains the "degree 227 * of their compatibility". It is always zero for user volumes. This field 228 * provides a mechanism to introduce UBI extensions and to be still compatible 229 * with older UBI binaries. For example, if someone introduced a journal in 230 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the 231 * journal volume. And in this case, older UBI binaries, which know nothing 232 * about the journal volume, would just delete this volume and work perfectly 233 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image 234 * - it just ignores the Ext3fs journal. 235 * 236 * The @data_crc field contains the CRC checksum of the contents of the logical 237 * eraseblock if this is a static volume. In case of dynamic volumes, it does 238 * not contain the CRC checksum as a rule. The only exception is when the 239 * data of the physical eraseblock was moved by the wear-leveling unit, then 240 * the wear-leveling unit calculates the data CRC and stores it in the 241 * @data_crc field. And of course, the @copy_flag is %in this case. 242 * 243 * The @data_size field is used only for static volumes because UBI has to know 244 * how many bytes of data are stored in this eraseblock. For dynamic volumes, 245 * this field usually contains zero. The only exception is when the data of the 246 * physical eraseblock was moved to another physical eraseblock for 247 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the 248 * contents and uses both @data_crc and @data_size fields. In this case, the 249 * @data_size field contains data size. 250 * 251 * The @used_ebs field is used only for static volumes and indicates how many 252 * eraseblocks the data of the volume takes. For dynamic volumes this field is 253 * not used and always contains zero. 254 * 255 * The @data_pad is calculated when volumes are created using the alignment 256 * parameter. So, effectively, the @data_pad field reduces the size of logical 257 * eraseblocks of this volume. This is very handy when one uses block-oriented 258 * software (say, cramfs) on top of the UBI volume. 259 */ 260 struct ubi_vid_hdr { 261 __be32 magic; 262 __u8 version; 263 __u8 vol_type; 264 __u8 copy_flag; 265 __u8 compat; 266 __be32 vol_id; 267 __be32 lnum; 268 __be32 leb_ver; /* obsolete, to be removed, don't use */ 269 __be32 data_size; 270 __be32 used_ebs; 271 __be32 data_pad; 272 __be32 data_crc; 273 __u8 padding1[4]; 274 __be64 sqnum; 275 __u8 padding2[12]; 276 __be32 hdr_crc; 277 } __attribute__ ((packed)); 278 279 /* Internal UBI volumes count */ 280 #define UBI_INT_VOL_COUNT 1 281 282 /* 283 * Starting ID of internal volumes. There is reserved room for 4096 internal 284 * volumes. 285 */ 286 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096) 287 288 /* The layout volume contains the volume table */ 289 290 #define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START 291 #define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC 292 #define UBI_LAYOUT_VOLUME_ALIGN 1 293 #define UBI_LAYOUT_VOLUME_EBS 2 294 #define UBI_LAYOUT_VOLUME_NAME "layout volume" 295 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT 296 297 /* The maximum number of volumes per one UBI device */ 298 #define UBI_MAX_VOLUMES 128 299 300 /* The maximum volume name length */ 301 #define UBI_VOL_NAME_MAX 127 302 303 /* Size of the volume table record */ 304 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record) 305 306 /* Size of the volume table record without the ending CRC */ 307 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32)) 308 309 /** 310 * struct ubi_vtbl_record - a record in the volume table. 311 * @reserved_pebs: how many physical eraseblocks are reserved for this volume 312 * @alignment: volume alignment 313 * @data_pad: how many bytes are unused at the end of the each physical 314 * eraseblock to satisfy the requested alignment 315 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME) 316 * @upd_marker: if volume update was started but not finished 317 * @name_len: volume name length 318 * @name: the volume name 319 * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG) 320 * @padding: reserved, zeroes 321 * @crc: a CRC32 checksum of the record 322 * 323 * The volume table records are stored in the volume table, which is stored in 324 * the layout volume. The layout volume consists of 2 logical eraseblock, each 325 * of which contains a copy of the volume table (i.e., the volume table is 326 * duplicated). The volume table is an array of &struct ubi_vtbl_record 327 * objects indexed by the volume ID. 328 * 329 * If the size of the logical eraseblock is large enough to fit 330 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES 331 * records. Otherwise, it contains as many records as it can fit (i.e., size of 332 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)). 333 * 334 * The @upd_marker flag is used to implement volume update. It is set to %1 335 * before update and set to %0 after the update. So if the update operation was 336 * interrupted, UBI knows that the volume is corrupted. 337 * 338 * The @alignment field is specified when the volume is created and cannot be 339 * later changed. It may be useful, for example, when a block-oriented file 340 * system works on top of UBI. The @data_pad field is calculated using the 341 * logical eraseblock size and @alignment. The alignment must be multiple to the 342 * minimal flash I/O unit. If @alignment is 1, all the available space of 343 * the physical eraseblocks is used. 344 * 345 * Empty records contain all zeroes and the CRC checksum of those zeroes. 346 */ 347 struct ubi_vtbl_record { 348 __be32 reserved_pebs; 349 __be32 alignment; 350 __be32 data_pad; 351 __u8 vol_type; 352 __u8 upd_marker; 353 __be16 name_len; 354 __u8 name[UBI_VOL_NAME_MAX+1]; 355 __u8 flags; 356 __u8 padding[23]; 357 __be32 crc; 358 } __attribute__ ((packed)); 359 360 #endif /* !__UBI_MEDIA_H__ */ 361