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-symbol-prefix <prefix> 121 122Remove ``<prefix>`` from the start of every symbol name. No-op for symbols that do 123not start with ``<prefix>``. 124 125.. option:: --remove-section <section>, -R 126 127 Remove the specified section from the output. Can be specified multiple times 128 to remove multiple sections simultaneously. 129 130 For MachO objects, ``<section>`` must be formatted as 131 ``<segment name>,<section name>``. 132 133.. option:: --set-section-alignment <section>=<align> 134 135 Set the alignment of section ``<section>`` to ``<align>``. Can be specified 136 multiple times to update multiple sections. 137 138.. option:: --set-section-flags <section>=<flag>[,<flag>,...] 139 140 Set section properties in the output of section ``<section>`` based on the 141 specified ``<flag>`` values. Can be specified multiple times to update multiple 142 sections. 143 144 Supported flag names are `alloc`, `load`, `noload`, `readonly`, `exclude`, 145 `debug`, `code`, `data`, `rom`, `share`, `contents`, `merge`, `strings`, and 146 `large`. Not all flags are meaningful for all object file formats or target 147 architectures. 148 149 For ELF objects, the flags have the following effects: 150 151 - `alloc` = add the `SHF_ALLOC` flag. 152 - `load` = if the section has `SHT_NOBITS` type, mark it as a `SHT_PROGBITS` 153 section. 154 - `readonly` = if this flag is not specified, add the `SHF_WRITE` flag. 155 - `exclude` = add the `SHF_EXCLUDE` flag. 156 - `code` = add the `SHF_EXECINSTR` flag. 157 - `merge` = add the `SHF_MERGE` flag. 158 - `strings` = add the `SHF_STRINGS` flag. 159 - `contents` = if the section has `SHT_NOBITS` type, mark it as a `SHT_PROGBITS` 160 section. 161 - `large` = add the `SHF_X86_64_LARGE` on x86_64; rejected if the target 162 architecture is not x86_64. 163 164 For COFF objects, the flags have the following effects: 165 166 - `alloc` = add the `IMAGE_SCN_CNT_UNINITIALIZED_DATA` and `IMAGE_SCN_MEM_READ` 167 flags, unless the `load` flag is specified. 168 - `noload` = add the `IMAGE_SCN_LNK_REMOVE` and `IMAGE_SCN_MEM_READ` flags. 169 - `readonly` = if this flag is not specified, add the `IMAGE_SCN_MEM_WRITE` 170 flag. 171 - `exclude` = add the `IMAGE_SCN_LNK_REMOVE` and `IMAGE_SCN_MEM_READ` flags. 172 - `debug` = add the `IMAGE_SCN_CNT_INITIALIZED_DATA`, 173 `IMAGE_SCN_MEM_DISCARDABLE` and `IMAGE_SCN_MEM_READ` flags. 174 - `code` = add the `IMAGE_SCN_CNT_CODE`, `IMAGE_SCN_MEM_EXECUTE` and 175 `IMAGE_SCN_MEM_READ` flags. 176 - `data` = add the `IMAGE_SCN_CNT_INITIALIZED_DATA` and `IMAGE_SCN_MEM_READ` 177 flags. 178 - `share` = add the `IMAGE_SCN_MEM_SHARED` and `IMAGE_SCN_MEM_READ` flags. 179 180.. option:: --strip-all-gnu 181 182 Remove all symbols, debug sections and relocations from the output. This option 183 is equivalent to GNU :program:`objcopy`'s ``--strip-all`` switch. 184 185.. option:: --strip-all, -S 186 187 For ELF objects, remove from the output all symbols and non-alloc sections not 188 within segments, except for .gnu.warning, .ARM.attribute sections and the 189 section name table. 190 191 For COFF and Mach-O objects, remove all symbols, debug sections, and 192 relocations from the output. 193 194.. option:: --strip-debug, -g 195 196 Remove all debug sections from the output. 197 198.. option:: --strip-symbol <symbol>, -N 199 200 Remove all symbols named ``<symbol>`` from the output. Can be specified 201 multiple times to remove multiple symbols. 202 203.. option:: --strip-symbols <filename> 204 205 Remove all symbols whose names appear in the file ``<filename>``, from the 206 output. In the file, each line represents a single symbol name, with leading 207 and trailing whitespace ignored, as is anything following a '#'. Can be 208 specified multiple times to read names from multiple files. 209 210.. option:: --strip-unneeded-symbol <symbol> 211 212 Remove from the output all symbols named ``<symbol>`` that are local or 213 undefined and are not required by any relocation. 214 215.. option:: --strip-unneeded-symbols <filename> 216 217 Remove all symbols whose names appear in the file ``<filename>``, from the 218 output, if they are local or undefined and are not required by any relocation. 219 In the file, each line represents a single symbol name, with leading and 220 trailing whitespace ignored, as is anything following a '#'. Can be specified 221 multiple times to read names from multiple files. 222 223.. option:: --strip-unneeded 224 225 Remove from the output all local or undefined symbols that are not required by 226 relocations. Also remove all debug sections. 227 228.. option:: --update-section <name>=<file> 229 230 Replace the contents of the section ``<name>`` with contents from the file 231 ``<file>``. If the section ``<name>`` is part of a segment, the new contents 232 cannot be larger than the existing section. 233 234.. option:: --version, -V 235 236 Display the version of the :program:`llvm-objcopy` executable. 237 238.. option:: --wildcard, -w 239 240 Allow wildcard syntax for symbol-related flags. On by default for 241 section-related flags. Incompatible with --regex. 242 243 Wildcard syntax allows the following special symbols: 244 245 ====================== ========================= ================== 246 Character Meaning Equivalent 247 ====================== ========================= ================== 248 ``*`` Any number of characters ``.*`` 249 ``?`` Any single character ``.`` 250 ``\`` Escape the next character ``\`` 251 ``[a-z]`` Character class ``[a-z]`` 252 ``[!a-z]``, ``[^a-z]`` Negated character class ``[^a-z]`` 253 ====================== ========================= ================== 254 255 Additionally, starting a wildcard with '!' will prevent a match, even if 256 another flag matches. For example ``-w -N '*' -N '!x'`` will strip all symbols 257 except for ``x``. 258 259 The order of wildcards does not matter. For example, ``-w -N '*' -N '!x'`` is 260 the same as ``-w -N '!x' -N '*'``. 261 262.. option:: @<FILE> 263 264 Read command-line options and commands from response file `<FILE>`. 265 266ELF-SPECIFIC OPTIONS 267-------------------- 268 269The following options are implemented only for ELF objects. If used with other 270objects, :program:`llvm-objcopy` will either emit an error or silently ignore 271them. 272 273.. option:: --add-symbol <name>=[<section>:]<value>[,<flags>] 274 275 Add a new symbol called ``<name>`` to the output symbol table, in the section 276 named ``<section>``, with value ``<value>``. If ``<section>`` is not specified, 277 the symbol is added as an absolute symbol. The ``<flags>`` affect the symbol 278 properties. Accepted values are: 279 280 - `global` = the symbol will have global binding. 281 - `local` = the symbol will have local binding. 282 - `weak` = the symbol will have weak binding. 283 - `default` = the symbol will have default visibility. 284 - `hidden` = the symbol will have hidden visibility. 285 - `protected` = the symbol will have protected visibility. 286 - `file` = the symbol will be an `STT_FILE` symbol. 287 - `section` = the symbol will be an `STT_SECTION` symbol. 288 - `object` = the symbol will be an `STT_OBJECT` symbol. 289 - `function` = the symbol will be an `STT_FUNC` symbol. 290 - `indirect-function` = the symbol will be an `STT_GNU_IFUNC` symbol. 291 292 Additionally, the following flags are accepted but ignored: `debug`, 293 `constructor`, `warning`, `indirect`, `synthetic`, `unique-object`, `before`. 294 295 Can be specified multiple times to add multiple symbols. 296 297.. option:: --allow-broken-links 298 299 Allow :program:`llvm-objcopy` to remove sections even if it would leave invalid 300 section references. Any invalid sh_link fields will be set to zero. 301 302.. option:: --change-start <incr>, --adjust-start 303 304 Add ``<incr>`` to the program's start address. Can be specified multiple 305 times, in which case the values will be applied cumulatively. 306 307.. option:: --compress-debug-sections [<format>] 308 309 Compress DWARF debug sections in the output, using the specified format. 310 Supported formats are ``zlib`` and ``zstd``. Use ``zlib`` if ``<format>`` is omitted. 311 312.. option:: --compress-sections <section>=<format> 313 314 Compress or decompress sections matched by ``<section>`` using the specified 315 format. Supported formats are ``zlib`` and ``zstd``. Specify ``none`` for 316 decompression. When a section is matched by multiple options, the last one 317 wins. A wildcard ``<section>`` starting with '!' is disallowed. 318 Sections within a segment cannot be (de)compressed. 319 320.. option:: --decompress-debug-sections 321 322 Decompress any compressed DWARF debug sections in the output. 323 324.. option:: --discard-locals, -X 325 326 Remove local symbols starting with ".L" from the output. 327 328.. option:: --extract-dwo 329 330 Remove all sections that are not DWARF .dwo sections from the output. 331 332.. option:: --extract-main-partition 333 334 Extract the main partition from the output. 335 336.. option:: --extract-partition <name> 337 338 Extract the named partition from the output. 339 340.. option:: --gap-fill <value> 341 342 For binary outputs, fill the gaps between sections with ``<value>`` instead 343 of zero. The value must be an unsigned 8-bit integer. 344 345.. option:: --globalize-symbol <symbol> 346 347 Mark any defined symbols named ``<symbol>`` as global symbols in the output. 348 Can be specified multiple times to mark multiple symbols. 349 350.. option:: --globalize-symbols <filename> 351 352 Read a list of names from the file ``<filename>`` and mark defined symbols with 353 those names as global in the output. In the file, each line represents a single 354 symbol, with leading and trailing whitespace ignored, as is anything following 355 a '#'. Can be specified multiple times to read names from multiple files. 356 357.. option:: --input-target <format>, -I 358 359 Read the input as the specified format. See `SUPPORTED FORMATS`_ for a list of 360 valid ``<format>`` values. If unspecified, :program:`llvm-objcopy` will attempt 361 to determine the format automatically. 362 363.. option:: --keep-file-symbols 364 365 Keep symbols of type `STT_FILE`, even if they would otherwise be stripped. 366 367.. option:: --keep-global-symbol <symbol>, -G 368 369 Mark all symbols local in the output, except for symbols with the name 370 ``<symbol>``. Can be specified multiple times to ignore multiple symbols. 371 372.. option:: --keep-global-symbols <filename> 373 374 Mark all symbols local in the output, except for symbols named in the file 375 ``<filename>``. In the file, each line represents a single symbol, with leading 376 and trailing whitespace ignored, as is anything following a '#'. Can be 377 specified multiple times to read names from multiple files. 378 379.. option:: --keep-section <section> 380 381 When removing sections from the output, do not remove sections named 382 ``<section>``. Can be specified multiple times to keep multiple sections. 383 384.. option:: --keep-symbol <symbol>, -K 385 386 When removing symbols from the output, do not remove symbols named 387 ``<symbol>``. Can be specified multiple times to keep multiple symbols. 388 389.. option:: --keep-symbols <filename> 390 391 When removing symbols from the output do not remove symbols named in the file 392 ``<filename>``. In the file, each line represents a single symbol, with leading 393 and trailing whitespace ignored, as is anything following a '#'. Can be 394 specified multiple times to read names from multiple files. 395 396.. option:: --localize-hidden 397 398 Mark all symbols with hidden or internal visibility local in the output. 399 400.. option:: --localize-symbol <symbol>, -L 401 402 Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the 403 output. Can be specified multiple times to mark multiple symbols as local. 404 405.. option:: --localize-symbols <filename> 406 407 Read a list of names from the file ``<filename>`` and mark defined non-common 408 symbols with those names as local in the output. In the file, each line 409 represents a single symbol, with leading and trailing whitespace ignored, as is 410 anything following a '#'. Can be specified multiple times to read names from 411 multiple files. 412 413.. option:: --new-symbol-visibility <visibility> 414 415 Specify the visibility of the symbols automatically created when using binary 416 input or :option:`--add-symbol`. Valid options are: 417 418 - `default` 419 - `hidden` 420 - `internal` 421 - `protected` 422 423 The default is `default`. 424 425.. option:: --output-target <format>, -O 426 427 Write the output as the specified format. See `SUPPORTED FORMATS`_ for a list 428 of valid ``<format>`` values. If unspecified, the output format is assumed to 429 be the same as the value specified for :option:`--input-target` or the input 430 file's format if that option is also unspecified. 431 432.. option:: --pad-to <address> 433 434 For binary outputs, pad the output to the load address ``<address>`` using a value 435 of zero or the value specified by :option:`--gap-fill`. 436 437.. option:: --prefix-alloc-sections <prefix> 438 439 Add ``<prefix>`` to the front of the names of all allocatable sections in the 440 output. 441 442.. option:: --prefix-symbols <prefix> 443 444 Add ``<prefix>`` to the front of every symbol name in the output. 445 446.. option:: --preserve-dates, -p 447 448 Preserve access and modification timestamps in the output. 449 450.. option:: --rename-section <old>=<new>[,<flag>,...] 451 452 Rename sections called ``<old>`` to ``<new>`` in the output, and apply any 453 specified ``<flag>`` values. See :option:`--set-section-flags` for a list of 454 supported flags. Can be specified multiple times to rename multiple sections. 455 456.. option:: --set-section-type <section>=<type> 457 458 Set the type of section ``<section>`` to the integer ``<type>``. Can be 459 specified multiple times to update multiple sections. 460 461.. option:: --set-start <addr> 462 463 Set the start address of the output to ``<addr>``. Overrides any previously 464 specified :option:`--change-start` or :option:`--adjust-start` options. 465 466.. option:: --set-symbol-visibility <symbol>=<visibility> 467 468 Change the visibility of a symbol to the specified value. 469 470.. option:: --set-symbols-visibility <filename>=<visibility> 471 472 Read a list of symbols from <filename> and change their visibility to the 473 specified value. Visibility values: default, internal, hidden, protected. 474 475.. option:: --skip-symbol <symbol> 476 477 Do not change the parameters of symbol ``<symbol>`` when executing other 478 options that can change the symbol's name, binding or visibility. 479 480.. option:: --skip-symbols <filename> 481 482 Do not change the parameters of symbols named in the file ``<filename>`` when 483 executing other options that can change the symbol's name, binding or 484 visibility. In the file, each line represents a single symbol, with leading 485 and trailing whitespace ignored, as is anything following a '#'. 486 Can be specified multiple times to read names from multiple files. 487 488.. option:: --split-dwo <dwo-file> 489 490 Equivalent to running :program:`llvm-objcopy` with :option:`--extract-dwo` and 491 ``<dwo-file>`` as the output file and no other options, and then with 492 :option:`--strip-dwo` on the input file. 493 494.. option:: --strip-dwo 495 496 Remove all DWARF .dwo sections from the output. 497 498.. option:: --strip-non-alloc 499 500 Remove from the output all non-allocatable sections that are not within 501 segments. 502 503.. option:: --strip-sections 504 505 Remove from the output all section headers and all section data not within 506 segments. Note that many tools will not be able to use an object without 507 section headers. 508 509.. option:: --target <format>, -F 510 511 Equivalent to :option:`--input-target` and :option:`--output-target` for the 512 specified format. See `SUPPORTED FORMATS`_ for a list of valid ``<format>`` 513 values. 514 515.. option:: --weaken-symbol <symbol>, -W 516 517 Mark global symbols named ``<symbol>`` as weak symbols in the output. Can 518 be specified multiple times to mark multiple symbols as weak. 519 520.. option:: --weaken-symbols <filename> 521 522 Read a list of names from the file ``<filename>`` and mark global symbols with 523 those names as weak in the output. In the file, each line represents a single 524 symbol, with leading and trailing whitespace ignored, as is anything following 525 a '#'. Can be specified multiple times to read names from multiple files. 526 527.. option:: --weaken 528 529 Mark all defined global symbols as weak in the output. 530 531MACH-O-SPECIFIC OPTIONS 532----------------------- 533 534.. option:: --keep-undefined 535 536 Keep undefined symbols, even if they would otherwise be stripped. 537 538COFF-SPECIFIC OPTIONS 539--------------------- 540 541.. option:: --subsystem <name>[:<version>] 542 543 Set the PE subsystem, and optionally subsystem version. 544 545SUPPORTED FORMATS 546----------------- 547 548The following values are currently supported by :program:`llvm-objcopy` for the 549:option:`--input-target`, :option:`--output-target`, and :option:`--target` 550options. For GNU :program:`objcopy` compatibility, the values are all bfdnames. 551 552- `binary` 553- `ihex` 554- `elf32-i386` 555- `elf32-x86-64` 556- `elf64-x86-64` 557- `elf32-iamcu` 558- `elf32-littlearm` 559- `elf64-aarch64` 560- `elf64-littleaarch64` 561- `elf32-littleriscv` 562- `elf64-littleriscv` 563- `elf32-powerpc` 564- `elf32-powerpcle` 565- `elf64-powerpc` 566- `elf64-powerpcle` 567- `elf32-bigmips` 568- `elf32-ntradbigmips` 569- `elf32-ntradlittlemips` 570- `elf32-tradbigmips` 571- `elf32-tradlittlemips` 572- `elf64-tradbigmips` 573- `elf64-tradlittlemips` 574- `elf32-sparc` 575- `elf32-sparcel` 576- `elf32-hexagon` 577- `elf32-loongarch` 578- `elf64-loongarch` 579- `elf64-s390` 580 581The following formats are suppoprted by :program:`llvm-objcopy` for the 582:option:`--output-target` only: 583 584- `srec` 585 586Additionally, all targets except `binary`, `ihex`, and `srec` can have 587`-freebsd` as a suffix. 588 589BINARY INPUT AND OUTPUT 590----------------------- 591 592If `binary` is used as the value for :option:`--input-target`, the input file 593will be embedded as a data section in an ELF relocatable object, with symbols 594``_binary_<file_name>_start``, ``_binary_<file_name>_end``, and 595``_binary_<file_name>_size`` representing the start, end and size of the data, 596where ``<file_name>`` is the path of the input file as specified on the command 597line with non-alphanumeric characters converted to ``_``. 598 599If `binary` is used as the value for :option:`--output-target`, the output file 600will be a raw binary file, containing the memory image of the input file. 601Symbols and relocation information will be discarded. The image will start at 602the address of the first loadable section in the output. 603 604EXIT STATUS 605----------- 606 607:program:`llvm-objcopy` exits with a non-zero exit code if there is an error. 608Otherwise, it exits with code 0. 609 610BUGS 611---- 612 613To report bugs, please visit <https://github.com/llvm/llvm-project/labels/tools:llvm-objcopy/strip/>. 614 615There is a known issue with :option:`--input-target` and :option:`--target` 616causing only ``binary`` and ``ihex`` formats to have any effect. Other values 617will be ignored and :program:`llvm-objcopy` will attempt to guess the input 618format. 619 620SEE ALSO 621-------- 622 623:manpage:`llvm-strip(1)` 624