LLVM-OBJCOPY(1) LLVM LLVM-OBJCOPY(1)
NAME
llvm-objcopy - object copying and editing tool
SYNOPSIS
llvm-objcopy [options] input [output]
DESCRIPTION
llvm-objcopy is a tool to copy and manipulate objects. In basic usage,
it makes a semantic copy of the input to the output. If any options are
specified, the output may be modified along the way, e.g. by removing
sections.
If no output file is specified, the input file is modified in-place. If
“-” is specified for the input file, the input is read from the pro-
gram’s standard input stream. If “-” is specified for the output file,
the output is written to the standard output stream of the program.
If the input is an archive, any requested operations will be applied to
each archive member individually.
The tool is still in active development, but in most scenarios it works
as a drop-in replacement for GNU’s objcopy.
GENERIC AND CROSS-PLATFORM OPTIONS
The following options are either agnostic of the file format, or apply
to multiple file formats.
--add-gnu-debuglink <debug-file>
Add a .gnu_debuglink section for <debug-file> to the output.
--add-section <section=file>
Add a section named <section> with the contents of <file> to the
output. For ELF objects the section will be of type SHT_NOTE, if
the name starts with “.note”. Otherwise, it will have type
SHT_PROGBITS. Can be specified multiple times to add multiple
sections.
For MachO objects, <section> must be formatted as <segment
name>,<section name>.
--binary-architecture <arch>, -B
Ignored for compatibility.
--disable-deterministic-archives, -U
Use real values for UIDs, GIDs and timestamps when updating ar-
chive member headers.
--discard-all, -x
Remove most local symbols from the output. Different file for-
mats may limit this to a subset of the local symbols. For exam-
ple, file and section symbols in ELF objects will not be dis-
carded. Additionally, remove all debug sections.
--dump-section <section>=<file>
Dump the contents of section <section> into the file <file>. Can
be specified multiple times to dump multiple sections to differ-
ent files. <file> is unrelated to the input and output files
provided to llvm-objcopy and as such the normal copying and
editing operations will still be performed. No operations are
performed on the sections prior to dumping them.
For MachO objects, <section> must be formatted as <segment
name>,<section name>.
--enable-deterministic-archives, -D
Enable deterministic mode when copying archives, i.e. use 0 for
archive member header UIDs, GIDs and timestamp fields. On by de-
fault.
--help, -h
Print a summary of command line options.
--only-keep-debug
Produce a debug file as the output that only preserves contents
of sections useful for debugging purposes.
For ELF objects, this removes the contents of SHF_ALLOC sections
that are not SHT_NOTE by making them SHT_NOBITS and shrinking
the program headers where possible.
--only-section <section>, -j
Remove all sections from the output, except for sections named
<section>. Can be specified multiple times to keep multiple
sections.
For MachO objects, <section> must be formatted as <segment
name>,<section name>.
--redefine-sym <old>=<new>
Rename symbols called <old> to <new> in the output. Can be spec-
ified multiple times to rename multiple symbols.
--redefine-syms <filename>
Rename symbols in the output as described in the file <file-
name>. In the file, each line represents a single symbol to re-
name, with the old name and new name separated by whitespace.
Leading and trailing whitespace is ignored, as is anything fol-
lowing a ‘#’. Can be specified multiple times to read names from
multiple files.
--regex
If specified, symbol and section names specified by other
switches are treated as extended POSIX regular expression pat-
terns.
--remove-section <section>, -R
Remove the specified section from the output. Can be specified
multiple times to remove multiple sections simultaneously.
For MachO objects, <section> must be formatted as <segment
name>,<section name>.
--set-section-alignment <section>=<align>
Set the alignment of section <section> to <align>. Can be speci-
fied multiple times to update multiple sections.
--set-section-flags <section>=<flag>[,<flag>,...]
Set section properties in the output of section <section> based
on the specified <flag> values. Can be specified multiple times
to update multiple sections.
Supported flag names are alloc, load, noload, readonly, exclude,
debug, code, data, rom, share, contents, merge and strings. Not
all flags are meaningful for all object file formats.
For ELF objects, the flags have the following effects:
• alloc = add the SHF_ALLOC flag.
• load = if the section has SHT_NOBITS type, mark it as a
SHT_PROGBITS section.
• readonly = if this flag is not specified, add the SHF_WRITE
flag.
• exclude = add the SHF_EXCLUDE flag.
• code = add the SHF_EXECINSTR flag.
• merge = add the SHF_MERGE flag.
• strings = add the SHF_STRINGS flag.
• contents = if the section has SHT_NOBITS type, mark it as a
SHT_PROGBITS section.
For COFF objects, the flags have the following effects:
• alloc = add the IMAGE_SCN_CNT_UNINITIALIZED_DATA and IM-
AGE_SCN_MEM_READ flags, unless the load flag is specified.
• noload = add the IMAGE_SCN_LNK_REMOVE and IMAGE_SCN_MEM_READ
flags.
• readonly = if this flag is not specified, add the IM-
AGE_SCN_MEM_WRITE flag.
• exclude = add the IMAGE_SCN_LNK_REMOVE and IMAGE_SCN_MEM_READ
flags.
• debug = add the IMAGE_SCN_CNT_INITIALIZED_DATA, IM-
AGE_SCN_MEM_DISCARDABLE and IMAGE_SCN_MEM_READ flags.
• code = add the IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE and
IMAGE_SCN_MEM_READ flags.
• data = add the IMAGE_SCN_CNT_INITIALIZED_DATA and IM-
AGE_SCN_MEM_READ flags.
• share = add the IMAGE_SCN_MEM_SHARED and IMAGE_SCN_MEM_READ
flags.
--strip-all-gnu
Remove all symbols, debug sections and relocations from the out-
put. This option is equivalent to GNU objcopy’s --strip-all
switch.
--strip-all, -S
For ELF objects, remove from the output all symbols and non-al-
loc sections not within segments, except for .gnu.warning,
.ARM.attribute sections and the section name table.
For COFF and Mach-O objects, remove all symbols, debug sections,
and relocations from the output.
--strip-debug, -g
Remove all debug sections from the output.
--strip-symbol <symbol>, -N
Remove all symbols named <symbol> from the output. Can be speci-
fied multiple times to remove multiple symbols.
--strip-symbols <filename>
Remove all symbols whose names appear in the file <filename>,
from the output. In the file, each line represents a single sym-
bol name, with leading and trailing whitespace ignored, as is
anything following a ‘#’. Can be specified multiple times to
read names from multiple files.
--strip-unneeded-symbol <symbol>
Remove from the output all symbols named <symbol> that are local
or undefined and are not required by any relocation.
--strip-unneeded-symbols <filename>
Remove all symbols whose names appear in the file <filename>,
from the output, if they are local or undefined and are not re-
quired by any relocation. In the file, each line represents a
single symbol name, with leading and trailing whitespace ig-
nored, as is anything following a ‘#’. Can be specified multiple
times to read names from multiple files.
--strip-unneeded
Remove from the output all local or undefined symbols that are
not required by relocations. Also remove all debug sections.
--update-section <name>=<file>
Replace the contents of the section <name> with contents from
the file <file>. If the section <name> is part of a segment, the
new contents cannot be larger than the existing section.
--version, -V
Display the version of the llvm-objcopy executable.
--wildcard, -w
Allow wildcard syntax for symbol-related flags. On by default
for section-related flags. Incompatible with –regex.
Wildcard syntax allows the following special symbols:
┌───────────────┬─────────────────────┬────────────┐
│Character │ Meaning │ Equivalent │
├───────────────┼─────────────────────┼────────────┤
│* │ Any number of char- │ .* │
│ │ acters │ │
├───────────────┼─────────────────────┼────────────┤
│? │ Any single charac- │ . │
│ │ ter │ │
├───────────────┼─────────────────────┼────────────┤
│\ │ Escape the next │ \ │
│ │ character │ │
├───────────────┼─────────────────────┼────────────┤
│[a-z] │ Character class │ [a-z] │
├───────────────┼─────────────────────┼────────────┤
│[!a-z], [^a-z] │ Negated character │ [^a-z] │
│ │ class │ │
└───────────────┴─────────────────────┴────────────┘
Additionally, starting a wildcard with ‘!’ will prevent a match,
even if another flag matches. For example -w -N '*' -N '!x' will
strip all symbols except for x.
The order of wildcards does not matter. For example, -w -N '*'
-N '!x' is the same as -w -N '!x' -N '*'.
@<FILE>
Read command-line options and commands from response file
<FILE>.
ELF-SPECIFIC OPTIONS
The following options are implemented only for ELF objects. If used
with other objects, llvm-objcopy will either emit an error or silently
ignore them.
--add-symbol <name>=[<section>:]<value>[,<flags>]
Add a new symbol called <name> to the output symbol table, in
the section named <section>, with value <value>. If <section> is
not specified, the symbol is added as an absolute symbol. The
<flags> affect the symbol properties. Accepted values are:
• global = the symbol will have global binding.
• local = the symbol will have local binding.
• weak = the symbol will have weak binding.
• default = the symbol will have default visibility.
• hidden = the symbol will have hidden visibility.
• protected = the symbol will have protected visibility.
• file = the symbol will be an STT_FILE symbol.
• section = the symbol will be an STT_SECTION symbol.
• object = the symbol will be an STT_OBJECT symbol.
• function = the symbol will be an STT_FUNC symbol.
• indirect-function = the symbol will be an STT_GNU_IFUNC sym-
bol.
Additionally, the following flags are accepted but ignored: de-
bug, constructor, warning, indirect, synthetic, unique-object,
before.
Can be specified multiple times to add multiple symbols.
--allow-broken-links
Allow llvm-objcopy to remove sections even if it would leave in-
valid section references. Any invalid sh_link fields will be set
to zero.
--change-start <incr>, --adjust-start
Add <incr> to the program’s start address. Can be specified mul-
tiple times, in which case the values will be applied cumula-
tively.
--compress-debug-sections [<format>]
Compress DWARF debug sections in the output, using the specified
format. Supported formats are zlib and zstd. Use zlib if <for-
mat> is omitted.
--decompress-debug-sections
Decompress any compressed DWARF debug sections in the output.
--discard-locals, -X
Remove local symbols starting with “.L” from the output.
--extract-dwo
Remove all sections that are not DWARF .dwo sections from the
output.
--extract-main-partition
Extract the main partition from the output.
--extract-partition <name>
Extract the named partition from the output.
--globalize-symbol <symbol>
Mark any defined symbols named <symbol> as global symbols in the
output. Can be specified multiple times to mark multiple sym-
bols.
--globalize-symbols <filename>
Read a list of names from the file <filename> and mark defined
symbols with those names as global in the output. In the file,
each line represents a single symbol, with leading and trailing
whitespace ignored, as is anything following a ‘#’. Can be spec-
ified multiple times to read names from multiple files.
--input-target <format>, -I
Read the input as the specified format. See SUPPORTED FORMATS
for a list of valid <format> values. If unspecified, llvm-obj-
copy will attempt to determine the format automatically.
--keep-file-symbols
Keep symbols of type STT_FILE, even if they would otherwise be
stripped.
--keep-global-symbol <symbol>, -G
Make all symbols local in the output, except for symbols with
the name <symbol>. Can be specified multiple times to ignore
multiple symbols.
--keep-global-symbols <filename>
Make all symbols local in the output, except for symbols named
in the file <filename>. In the file, each line represents a sin-
gle symbol, with leading and trailing whitespace ignored, as is
anything following a ‘#’. Can be specified multiple times to
read names from multiple files.
--keep-section <section>
When removing sections from the output, do not remove sections
named <section>. Can be specified multiple times to keep multi-
ple sections.
--keep-symbol <symbol>, -K
When removing symbols from the output, do not remove symbols
named <symbol>. Can be specified multiple times to keep multiple
symbols.
--keep-symbols <filename>
When removing symbols from the output do not remove symbols
named in the file <filename>. In the file, each line represents
a single symbol, with leading and trailing whitespace ignored,
as is anything following a ‘#’. Can be specified multiple times
to read names from multiple files.
--localize-hidden
Make all symbols with hidden or internal visibility local in the
output.
--localize-symbol <symbol>, -L
Mark any defined non-common symbol named <symbol> as a local
symbol in the output. Can be specified multiple times to mark
multiple symbols as local.
--localize-symbols <filename>
Read a list of names from the file <filename> and mark defined
non-common symbols with those names as local in the output. In
the file, each line represents a single symbol, with leading and
trailing whitespace ignored, as is anything following a ‘#’. Can
be specified multiple times to read names from multiple files.
--new-symbol-visibility <visibility>
Specify the visibility of the symbols automatically created when
using binary input or --add-symbol. Valid options are:
• default
• hidden
• internal
• protected
The default is default.
--output-target <format>, -O
Write the output as the specified format. See SUPPORTED FORMATS
for a list of valid <format> values. If unspecified, the output
format is assumed to be the same as the value specified for
--input-target or the input file’s format if that option is also
unspecified.
--prefix-alloc-sections <prefix>
Add <prefix> to the front of the names of all allocatable sec-
tions in the output.
--prefix-symbols <prefix>
Add <prefix> to the front of every symbol name in the output.
--preserve-dates, -p
Preserve access and modification timestamps in the output.
--rename-section <old>=<new>[,<flag>,...]
Rename sections called <old> to <new> in the output, and apply
any specified <flag> values. See --set-section-flags for a list
of supported flags. Can be specified multiple times to rename
multiple sections.
--set-section-type <section>=<type>
Set the type of section <section> to the integer <type>. Can be
specified multiple times to update multiple sections.
--set-start-addr <addr>
Set the start address of the output to <addr>. Overrides any
previously specified --change-start or --adjust-start options.
--split-dwo <dwo-file>
Equivalent to running llvm-objcopy with --extract-dwo and
<dwo-file> as the output file and no other options, and then
with --strip-dwo on the input file.
--strip-dwo
Remove all DWARF .dwo sections from the output.
--strip-non-alloc
Remove from the output all non-allocatable sections that are not
within segments.
--strip-sections
Remove from the output all section headers and all section data
not within segments. Note that many tools will not be able to
use an object without section headers.
--target <format>, -F
Equivalent to --input-target and --output-target for the speci-
fied format. See SUPPORTED FORMATS for a list of valid <format>
values.
--weaken-symbol <symbol>, -W
Mark any global symbol named <symbol> as a weak symbol in the
output. Can be specified multiple times to mark multiple symbols
as weak.
--weaken-symbols <filename>
Read a list of names from the file <filename> and mark global
symbols with those names as weak in the output. In the file,
each line represents a single symbol, with leading and trailing
whitespace ignored, as is anything following a ‘#’. Can be spec-
ified multiple times to read names from multiple files.
--weaken
Mark all defined global symbols as weak in the output.
MACH-O-SPECIFIC OPTIONS
--keep-undefined
Keep undefined symbols, even if they would otherwise be
stripped.
COFF-SPECIFIC OPTIONS
--subsystem <name>[:<version>]
Set the PE subsystem, and optionally subsystem version.
SUPPORTED FORMATS
The following values are currently supported by llvm-objcopy for the
--input-target, --output-target, and --target options. For GNU objcopy
compatibility, the values are all bfdnames.
• binary
• ihex
• elf32-i386
• elf32-x86-64
• elf64-x86-64
• elf32-iamcu
• elf32-littlearm
• elf64-aarch64
• elf64-littleaarch64
• elf32-littleriscv
• elf64-littleriscv
• elf32-powerpc
• elf32-powerpcle
• elf64-powerpc
• elf64-powerpcle
• elf32-bigmips
• elf32-ntradbigmips
• elf32-ntradlittlemips
• elf32-tradbigmips
• elf32-tradlittlemips
• elf64-tradbigmips
• elf64-tradlittlemips
• elf32-sparc
• elf32-sparcel
Additionally, all targets except binary and ihex can have -freebsd as a
suffix.
BINARY INPUT AND OUTPUT
If binary is used as the value for --input-target, the input file will
be embedded as a data section in an ELF relocatable object, with sym-
bols _binary_<file_name>_start, _binary_<file_name>_end, and _bi-
nary_<file_name>_size representing the start, end and size of the data,
where <file_name> is the path of the input file as specified on the
command line with non-alphanumeric characters converted to _.
If binary is used as the value for --output-target, the output file
will be a raw binary file, containing the memory image of the input
file. Symbols and relocation information will be discarded. The image
will start at the address of the first loadable section in the output.
EXIT STATUS
llvm-objcopy exits with a non-zero exit code if there is an error.
Otherwise, it exits with code 0.
BUGS
To report bugs, please visit <-
https://github.com/llvm/llvm-project/labels/tools:llvm-objcopy/strip/>.
There is a known issue with --input-target and --target causing only
binary and ihex formats to have any effect. Other values will be ig-
nored and llvm-objcopy will attempt to guess the input format.
SEE ALSO
llvm-strip(1)
AUTHOR
Maintained by the LLVM Team (https://llvm.org/).
COPYRIGHT
2003-2023, LLVM Project
15 2023-10-16 LLVM-OBJCOPY(1)
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