1llvm-objcopy - object copying and editing tool 2============================================== 3 4.. program:: llvm-objcopy 5 6SYNOPSIS 7-------- 8 9:program:`llvm-objcopy` [*options*] *input* [*output*] 10 11DESCRIPTION 12----------- 13 14:program:`llvm-objcopy` is a tool to copy and manipulate objects. In basic 15usage, it makes a semantic copy of the input to the output. If any options are 16specified, the output may be modified along the way, e.g. by removing sections. 17 18If no output file is specified, the input file is modified in-place. If "-" is 19specified for the input file, the input is read from the program's standard 20input stream. If "-" is specified for the output file, the output is written to 21the standard output stream of the program. 22 23If the input is an archive, any requested operations will be applied to each 24archive member individually. 25 26The tool is still in active development, but in most scenarios it works as a 27drop-in replacement for GNU's :program:`objcopy`. 28 29GENERIC AND CROSS-PLATFORM OPTIONS 30---------------------------------- 31 32The following options are either agnostic of the file format, or apply to 33multiple file formats. 34 35.. option:: --add-gnu-debuglink <debug-file> 36 37 Add a .gnu_debuglink section for ``<debug-file>`` to the output. 38 39.. option:: --add-section <section=file> 40 41 Add a section named ``<section>`` with the contents of ``<file>`` to the 42 output. For ELF objects the section will be of type `SHT_NOTE`, if the name 43 starts with ".note". Otherwise, it will have type `SHT_PROGBITS`. Can be 44 specified multiple times to add multiple sections. 45 46 For MachO objects, ``<section>`` must be formatted as 47 ``<segment name>,<section name>``. 48 49.. option:: --binary-architecture <arch>, -B 50 51 Ignored for compatibility. 52 53.. option:: --disable-deterministic-archives, -U 54 55 Use real values for UIDs, GIDs and timestamps when updating archive member 56 headers. 57 58.. option:: --discard-all, -x 59 60 Remove most local symbols from the output. Different file formats may limit 61 this to a subset of the local symbols. For example, file and section symbols in 62 ELF objects will not be discarded. Additionally, remove all debug sections. 63 64.. option:: --dump-section <section>=<file> 65 66 Dump the contents of section ``<section>`` into the file ``<file>``. Can be 67 specified multiple times to dump multiple sections to different files. 68 ``<file>`` is unrelated to the input and output files provided to 69 :program:`llvm-objcopy` and as such the normal copying and editing 70 operations will still be performed. No operations are performed on the sections 71 prior to dumping them. 72 73 For MachO objects, ``<section>`` must be formatted as 74 ``<segment name>,<section name>``. 75 76.. option:: --enable-deterministic-archives, -D 77 78 Enable deterministic mode when copying archives, i.e. use 0 for archive member 79 header UIDs, GIDs and timestamp fields. On by default. 80 81.. option:: --help, -h 82 83 Print a summary of command line options. 84 85.. option:: --only-keep-debug 86 87 Produce a debug file as the output that only preserves contents of sections 88 useful for debugging purposes. 89 90 For ELF objects, this removes the contents of `SHF_ALLOC` sections that are not 91 `SHT_NOTE` by making them `SHT_NOBITS` and shrinking the program headers where 92 possible. 93 94.. option:: --only-section <section>, -j 95 96 Remove all sections from the output, except for sections named ``<section>``. 97 Can be specified multiple times to keep multiple sections. 98 99 For MachO objects, ``<section>`` must be formatted as 100 ``<segment name>,<section name>``. 101 102.. option:: --redefine-sym <old>=<new> 103 104 Rename symbols called ``<old>`` to ``<new>`` in the output. Can be specified 105 multiple times to rename multiple symbols. 106 107.. option:: --redefine-syms <filename> 108 109 Rename symbols in the output as described in the file ``<filename>``. In the 110 file, each line represents a single symbol to rename, with the old name and new 111 name separated by whitespace. Leading and trailing whitespace is ignored, as is 112 anything following a '#'. Can be specified multiple times to read names from 113 multiple files. 114 115.. option:: --regex 116 117 If specified, symbol and section names specified by other switches are treated 118 as extended POSIX regular expression patterns. 119 120.. option:: --remove-section <section>, -R 121 122 Remove the specified section from the output. Can be specified multiple times 123 to remove multiple sections simultaneously. 124 125 For MachO objects, ``<section>`` must be formatted as 126 ``<segment name>,<section name>``. 127 128.. option:: --set-section-alignment <section>=<align> 129 130 Set the alignment of section ``<section>`` to ``<align>``. Can be specified 131 multiple times to update multiple sections. 132 133.. option:: --set-section-flags <section>=<flag>[,<flag>,...] 134 135 Set section properties in the output of section ``<section>`` based on the 136 specified ``<flag>`` values. Can be specified multiple times to update multiple 137 sections. 138 139 Supported flag names are `alloc`, `load`, `noload`, `readonly`, `exclude`, 140 `debug`, `code`, `data`, `rom`, `share`, `contents`, `merge` and `strings`. Not 141 all flags are meaningful for all object file formats. 142 143 For ELF objects, the flags have the following effects: 144 145 - `alloc` = add the `SHF_ALLOC` flag. 146 - `load` = if the section has `SHT_NOBITS` type, mark it as a `SHT_PROGBITS` 147 section. 148 - `readonly` = if this flag is not specified, add the `SHF_WRITE` flag. 149 - `exclude` = add the `SHF_EXCLUDE` flag. 150 - `code` = add the `SHF_EXECINSTR` flag. 151 - `merge` = add the `SHF_MERGE` flag. 152 - `strings` = add the `SHF_STRINGS` flag. 153 - `contents` = if the section has `SHT_NOBITS` type, mark it as a `SHT_PROGBITS` 154 section. 155 156 For COFF objects, the flags have the following effects: 157 158 - `alloc` = add the `IMAGE_SCN_CNT_UNINITIALIZED_DATA` and `IMAGE_SCN_MEM_READ` 159 flags, unless the `load` flag is specified. 160 - `noload` = add the `IMAGE_SCN_LNK_REMOVE` and `IMAGE_SCN_MEM_READ` flags. 161 - `readonly` = if this flag is not specified, add the `IMAGE_SCN_MEM_WRITE` 162 flag. 163 - `exclude` = add the `IMAGE_SCN_LNK_REMOVE` and `IMAGE_SCN_MEM_READ` flags. 164 - `debug` = add the `IMAGE_SCN_CNT_INITIALIZED_DATA`, 165 `IMAGE_SCN_MEM_DISCARDABLE` and `IMAGE_SCN_MEM_READ` flags. 166 - `code` = add the `IMAGE_SCN_CNT_CODE`, `IMAGE_SCN_MEM_EXECUTE` and 167 `IMAGE_SCN_MEM_READ` flags. 168 - `data` = add the `IMAGE_SCN_CNT_INITIALIZED_DATA` and `IMAGE_SCN_MEM_READ` 169 flags. 170 - `share` = add the `IMAGE_SCN_MEM_SHARED` and `IMAGE_SCN_MEM_READ` flags. 171 172.. option:: --strip-all-gnu 173 174 Remove all symbols, debug sections and relocations from the output. This option 175 is equivalent to GNU :program:`objcopy`'s ``--strip-all`` switch. 176 177.. option:: --strip-all, -S 178 179 For ELF objects, remove from the output all symbols and non-alloc sections not 180 within segments, except for .gnu.warning, .ARM.attribute sections and the 181 section name table. 182 183 For COFF and Mach-O objects, remove all symbols, debug sections, and 184 relocations from the output. 185 186.. option:: --strip-debug, -g 187 188 Remove all debug sections from the output. 189 190.. option:: --strip-symbol <symbol>, -N 191 192 Remove all symbols named ``<symbol>`` from the output. Can be specified 193 multiple times to remove multiple symbols. 194 195.. option:: --strip-symbols <filename> 196 197 Remove all symbols whose names appear in the file ``<filename>``, from the 198 output. In the file, each line represents a single symbol name, with leading 199 and trailing whitespace ignored, as is anything following a '#'. Can be 200 specified multiple times to read names from multiple files. 201 202.. option:: --strip-unneeded-symbol <symbol> 203 204 Remove from the output all symbols named ``<symbol>`` that are local or 205 undefined and are not required by any relocation. 206 207.. option:: --strip-unneeded-symbols <filename> 208 209 Remove all symbols whose names appear in the file ``<filename>``, from the 210 output, if they are local or undefined and are not required by any relocation. 211 In the file, each line represents a single symbol name, with leading and 212 trailing whitespace ignored, as is anything following a '#'. Can be specified 213 multiple times to read names from multiple files. 214 215.. option:: --strip-unneeded 216 217 Remove from the output all local or undefined symbols that are not required by 218 relocations. Also remove all debug sections. 219 220.. option:: --update-section <name>=<file> 221 222 Replace the contents of the section ``<name>`` with contents from the file 223 ``<file>``. If the section ``<name>`` is part of a segment, the new contents 224 cannot be larger than the existing section. 225 226.. option:: --version, -V 227 228 Display the version of the :program:`llvm-objcopy` executable. 229 230.. option:: --wildcard, -w 231 232 Allow wildcard syntax for symbol-related flags. On by default for 233 section-related flags. Incompatible with --regex. 234 235 Wildcard syntax allows the following special symbols: 236 237 ====================== ========================= ================== 238 Character Meaning Equivalent 239 ====================== ========================= ================== 240 ``*`` Any number of characters ``.*`` 241 ``?`` Any single character ``.`` 242 ``\`` Escape the next character ``\`` 243 ``[a-z]`` Character class ``[a-z]`` 244 ``[!a-z]``, ``[^a-z]`` Negated character class ``[^a-z]`` 245 ====================== ========================= ================== 246 247 Additionally, starting a wildcard with '!' will prevent a match, even if 248 another flag matches. For example ``-w -N '*' -N '!x'`` will strip all symbols 249 except for ``x``. 250 251 The order of wildcards does not matter. For example, ``-w -N '*' -N '!x'`` is 252 the same as ``-w -N '!x' -N '*'``. 253 254.. option:: @<FILE> 255 256 Read command-line options and commands from response file `<FILE>`. 257 258ELF-SPECIFIC OPTIONS 259-------------------- 260 261The following options are implemented only for ELF objects. If used with other 262objects, :program:`llvm-objcopy` will either emit an error or silently ignore 263them. 264 265.. option:: --add-symbol <name>=[<section>:]<value>[,<flags>] 266 267 Add a new symbol called ``<name>`` to the output symbol table, in the section 268 named ``<section>``, with value ``<value>``. If ``<section>`` is not specified, 269 the symbol is added as an absolute symbol. The ``<flags>`` affect the symbol 270 properties. Accepted values are: 271 272 - `global` = the symbol will have global binding. 273 - `local` = the symbol will have local binding. 274 - `weak` = the symbol will have weak binding. 275 - `default` = the symbol will have default visibility. 276 - `hidden` = the symbol will have hidden visibility. 277 - `protected` = the symbol will have protected visibility. 278 - `file` = the symbol will be an `STT_FILE` symbol. 279 - `section` = the symbol will be an `STT_SECTION` symbol. 280 - `object` = the symbol will be an `STT_OBJECT` symbol. 281 - `function` = the symbol will be an `STT_FUNC` symbol. 282 - `indirect-function` = the symbol will be an `STT_GNU_IFUNC` symbol. 283 284 Additionally, the following flags are accepted but ignored: `debug`, 285 `constructor`, `warning`, `indirect`, `synthetic`, `unique-object`, `before`. 286 287 Can be specified multiple times to add multiple symbols. 288 289.. option:: --allow-broken-links 290 291 Allow :program:`llvm-objcopy` to remove sections even if it would leave invalid 292 section references. Any invalid sh_link fields will be set to zero. 293 294.. option:: --change-start <incr>, --adjust-start 295 296 Add ``<incr>`` to the program's start address. Can be specified multiple 297 times, in which case the values will be applied cumulatively. 298 299.. option:: --compress-debug-sections [<format>] 300 301 Compress DWARF debug sections in the output, using the specified format. 302 Supported formats are ``zlib`` and ``zstd``. Use ``zlib`` if ``<format>`` is omitted. 303 304.. option:: --decompress-debug-sections 305 306 Decompress any compressed DWARF debug sections in the output. 307 308.. option:: --discard-locals, -X 309 310 Remove local symbols starting with ".L" from the output. 311 312.. option:: --extract-dwo 313 314 Remove all sections that are not DWARF .dwo sections from the output. 315 316.. option:: --extract-main-partition 317 318 Extract the main partition from the output. 319 320.. option:: --extract-partition <name> 321 322 Extract the named partition from the output. 323 324.. option:: --globalize-symbol <symbol> 325 326 Mark any defined symbols named ``<symbol>`` as global symbols in the output. 327 Can be specified multiple times to mark multiple symbols. 328 329.. option:: --globalize-symbols <filename> 330 331 Read a list of names from the file ``<filename>`` and mark defined symbols with 332 those names as global in the output. In the file, each line represents a single 333 symbol, with leading and trailing whitespace ignored, as is anything following 334 a '#'. Can be specified multiple times to read names from multiple files. 335 336.. option:: --input-target <format>, -I 337 338 Read the input as the specified format. See `SUPPORTED FORMATS`_ for a list of 339 valid ``<format>`` values. If unspecified, :program:`llvm-objcopy` will attempt 340 to determine the format automatically. 341 342.. option:: --keep-file-symbols 343 344 Keep symbols of type `STT_FILE`, even if they would otherwise be stripped. 345 346.. option:: --keep-global-symbol <symbol>, -G 347 348 Make all symbols local in the output, except for symbols with the name 349 ``<symbol>``. Can be specified multiple times to ignore multiple symbols. 350 351.. option:: --keep-global-symbols <filename> 352 353 Make all symbols local in the output, except for symbols named in the file 354 ``<filename>``. In the file, each line represents a single symbol, with leading 355 and trailing whitespace ignored, as is anything following a '#'. Can be 356 specified multiple times to read names from multiple files. 357 358.. option:: --keep-section <section> 359 360 When removing sections from the output, do not remove sections named 361 ``<section>``. Can be specified multiple times to keep multiple sections. 362 363.. option:: --keep-symbol <symbol>, -K 364 365 When removing symbols from the output, do not remove symbols named 366 ``<symbol>``. Can be specified multiple times to keep multiple symbols. 367 368.. option:: --keep-symbols <filename> 369 370 When removing symbols from the output do not remove symbols named in the file 371 ``<filename>``. In the file, each line represents a single symbol, with leading 372 and trailing whitespace ignored, as is anything following a '#'. Can be 373 specified multiple times to read names from multiple files. 374 375.. option:: --localize-hidden 376 377 Make all symbols with hidden or internal visibility local in the output. 378 379.. option:: --localize-symbol <symbol>, -L 380 381 Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the 382 output. Can be specified multiple times to mark multiple symbols as local. 383 384.. option:: --localize-symbols <filename> 385 386 Read a list of names from the file ``<filename>`` and mark defined non-common 387 symbols with those names as local in the output. In the file, each line 388 represents a single symbol, with leading and trailing whitespace ignored, as is 389 anything following a '#'. Can be specified multiple times to read names from 390 multiple files. 391 392.. option:: --new-symbol-visibility <visibility> 393 394 Specify the visibility of the symbols automatically created when using binary 395 input or :option:`--add-symbol`. Valid options are: 396 397 - `default` 398 - `hidden` 399 - `internal` 400 - `protected` 401 402 The default is `default`. 403 404.. option:: --output-target <format>, -O 405 406 Write the output as the specified format. See `SUPPORTED FORMATS`_ for a list 407 of valid ``<format>`` values. If unspecified, the output format is assumed to 408 be the same as the value specified for :option:`--input-target` or the input 409 file's format if that option is also unspecified. 410 411.. option:: --prefix-alloc-sections <prefix> 412 413 Add ``<prefix>`` to the front of the names of all allocatable sections in the 414 output. 415 416.. option:: --prefix-symbols <prefix> 417 418 Add ``<prefix>`` to the front of every symbol name in the output. 419 420.. option:: --preserve-dates, -p 421 422 Preserve access and modification timestamps in the output. 423 424.. option:: --rename-section <old>=<new>[,<flag>,...] 425 426 Rename sections called ``<old>`` to ``<new>`` in the output, and apply any 427 specified ``<flag>`` values. See :option:`--set-section-flags` for a list of 428 supported flags. Can be specified multiple times to rename multiple sections. 429 430.. option:: --set-section-type <section>=<type> 431 432 Set the type of section ``<section>`` to the integer ``<type>``. Can be 433 specified multiple times to update multiple sections. 434 435.. option:: --set-start-addr <addr> 436 437 Set the start address of the output to ``<addr>``. Overrides any previously 438 specified :option:`--change-start` or :option:`--adjust-start` options. 439 440.. option:: --split-dwo <dwo-file> 441 442 Equivalent to running :program:`llvm-objcopy` with :option:`--extract-dwo` and 443 ``<dwo-file>`` as the output file and no other options, and then with 444 :option:`--strip-dwo` on the input file. 445 446.. option:: --strip-dwo 447 448 Remove all DWARF .dwo sections from the output. 449 450.. option:: --strip-non-alloc 451 452 Remove from the output all non-allocatable sections that are not within 453 segments. 454 455.. option:: --strip-sections 456 457 Remove from the output all section headers and all section data not within 458 segments. Note that many tools will not be able to use an object without 459 section headers. 460 461.. option:: --target <format>, -F 462 463 Equivalent to :option:`--input-target` and :option:`--output-target` for the 464 specified format. See `SUPPORTED FORMATS`_ for a list of valid ``<format>`` 465 values. 466 467.. option:: --weaken-symbol <symbol>, -W 468 469 Mark any global symbol named ``<symbol>`` as a weak symbol in the output. Can 470 be specified multiple times to mark multiple symbols as weak. 471 472.. option:: --weaken-symbols <filename> 473 474 Read a list of names from the file ``<filename>`` and mark global symbols with 475 those names as weak in the output. In the file, each line represents a single 476 symbol, with leading and trailing whitespace ignored, as is anything following 477 a '#'. Can be specified multiple times to read names from multiple files. 478 479.. option:: --weaken 480 481 Mark all defined global symbols as weak in the output. 482 483MACH-O-SPECIFIC OPTIONS 484----------------------- 485 486.. option:: --keep-undefined 487 488 Keep undefined symbols, even if they would otherwise be stripped. 489 490COFF-SPECIFIC OPTIONS 491--------------------- 492 493.. option:: --subsystem <name>[:<version>] 494 495 Set the PE subsystem, and optionally subsystem version. 496 497SUPPORTED FORMATS 498----------------- 499 500The following values are currently supported by :program:`llvm-objcopy` for the 501:option:`--input-target`, :option:`--output-target`, and :option:`--target` 502options. For GNU :program:`objcopy` compatibility, the values are all bfdnames. 503 504- `binary` 505- `ihex` 506- `elf32-i386` 507- `elf32-x86-64` 508- `elf64-x86-64` 509- `elf32-iamcu` 510- `elf32-littlearm` 511- `elf64-aarch64` 512- `elf64-littleaarch64` 513- `elf32-littleriscv` 514- `elf64-littleriscv` 515- `elf32-powerpc` 516- `elf32-powerpcle` 517- `elf64-powerpc` 518- `elf64-powerpcle` 519- `elf32-bigmips` 520- `elf32-ntradbigmips` 521- `elf32-ntradlittlemips` 522- `elf32-tradbigmips` 523- `elf32-tradlittlemips` 524- `elf64-tradbigmips` 525- `elf64-tradlittlemips` 526- `elf32-sparc` 527- `elf32-sparcel` 528 529Additionally, all targets except `binary` and `ihex` can have `-freebsd` as a 530suffix. 531 532BINARY INPUT AND OUTPUT 533----------------------- 534 535If `binary` is used as the value for :option:`--input-target`, the input file 536will be embedded as a data section in an ELF relocatable object, with symbols 537``_binary_<file_name>_start``, ``_binary_<file_name>_end``, and 538``_binary_<file_name>_size`` representing the start, end and size of the data, 539where ``<file_name>`` is the path of the input file as specified on the command 540line with non-alphanumeric characters converted to ``_``. 541 542If `binary` is used as the value for :option:`--output-target`, the output file 543will be a raw binary file, containing the memory image of the input file. 544Symbols and relocation information will be discarded. The image will start at 545the address of the first loadable section in the output. 546 547EXIT STATUS 548----------- 549 550:program:`llvm-objcopy` exits with a non-zero exit code if there is an error. 551Otherwise, it exits with code 0. 552 553BUGS 554---- 555 556To report bugs, please visit <https://github.com/llvm/llvm-project/labels/tools:llvm-objcopy/strip/>. 557 558There is a known issue with :option:`--input-target` and :option:`--target` 559causing only ``binary`` and ``ihex`` formats to have any effect. Other values 560will be ignored and :program:`llvm-objcopy` will attempt to guess the input 561format. 562 563SEE ALSO 564-------- 565 566:manpage:`llvm-strip(1)` 567