llvm-objcopy - object copying and editing tool
llvm-objcopy [options] input
[output]
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 program’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.
The following options are either agnostic of the file format, or
apply to multiple file formats.
- --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>.
- --discard-all,
-x
- Remove most local symbols from the output. Different file formats may
limit this to a subset of the local symbols. For example, file and section
symbols in ELF objects will not be discarded. 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 different 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>.
- --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 specified multiple times to rename multiple symbols.
- --redefine-syms
<filename>
- Rename symbols in the output as described in the file
<filename>. In the file, each line represents a single symbol
to rename, with the old name and new name separated by whitespace. Leading
and trailing whitespace is ignored, as is anything following 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 patterns.
- --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-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
IMAGE_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
IMAGE_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,
IMAGE_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
IMAGE_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 output. 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-alloc 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-symbol
<symbol>, -N
- Remove all symbols named <symbol> from the output. Can be
specified 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 symbol 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-symbols
<filename>
- Remove all symbols whose names appear in the file <filename>,
from the output, if they are local or undefined and are not required by
any relocation. In the file, each line represents a single symbol 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
- 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 characters |
.* |
? |
Any single character |
. |
\ |
Escape the next character |
\ |
[a-z] |
Character class |
[a-z] |
[!a-z], [^a-z] |
Negated character class |
[^a-z] |
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>.
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
symbol.
Additionally, the following flags are accepted but ignored:
debug, 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
invalid section references. Any invalid sh_link fields will be set to
zero.
- Remove all sections that are not DWARF .dwo sections from the output.
- Extract the main partition from the output.
- 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 symbols.
- --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 specified
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-objcopy will attempt to determine the format
automatically.
- --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 single
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 multiple
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.
- --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-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
specified 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 specified multiple
times to read names from multiple files.
- --weaken
- Mark all defined global symbols as weak in the output.
- --keep-undefined
- Keep undefined symbols, even if they would otherwise be stripped.
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.
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 symbols _binary_<file_name>_start,
_binary_<file_name>_end, and
_binary_<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.
llvm-objcopy exits with a non-zero exit code if there is an
error. Otherwise, it exits with code 0.
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 ignored and llvm-objcopy will
attempt to guess the input format.
Maintained by the LLVM Team (https://llvm.org/).