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