- infile
- outfile
- The input and output files, respectively.
If you do not specify outfile, objcopy creates a
temporary file and destructively renames the result with
the name of infile.
- -I bfdname
- --input-target=bfdname
- Consider the source file's object format to be bfdname, rather than
attempting to deduce it. See Target Selection, for more information.
- -O bfdname
- --output-target=bfdname
- Write the output file using the object format bfdname.
See Target Selection, for more information.
- -F bfdname
- --target=bfdname
- Use bfdname as the object format for both the input and the output
file; i.e., simply transfer data from source to destination with no
translation. See Target Selection, for more information.
- -B bfdarch
- --binary-architecture=bfdarch
- Useful when transforming a architecture-less input file into an object file.
In this case the output architecture can be set to bfdarch. This
option will be ignored if the input file has a known bfdarch. You
can access this binary data inside a program by referencing the special
symbols that are created by the conversion process. These symbols are
called _binary_objfile_start, _binary_objfile_end and
_binary_objfile_size. e.g. you can transform a picture file into
an object file and then access it in your code using these symbols.
- -j sectionpattern
- --only-section=sectionpattern
- Copy only the indicated sections from the input file to the output file.
This option may be given more than once. Note that using this option
inappropriately may make the output file unusable. Wildcard
characters are accepted in sectionpattern.
If the first character of sectionpattern is the exclamation
point (!) then matching sections will not be copied, even if earlier
use of --only-section on the same command line would
otherwise copy it. For example:
--only-section=.text.* --only-section=!.text.foo
will copy all sectinos maching '.text.*' but not the section
'.text.foo'.
- -R sectionpattern
- --remove-section=sectionpattern
- Remove any section matching sectionpattern from the output file.
This option may be given more than once. Note that using this option
inappropriately may make the output file unusable. Wildcard
characters are accepted in sectionpattern. Using both the
-j and -R options together results in undefined
behaviour.
If the first character of sectionpattern is the exclamation
point (!) then matching sections will not be removed even if an
earlier use of --remove-section on the same command line
would otherwise remove it. For example:
--remove-section=.text.* --remove-section=!.text.foo
will remove all sections matching the pattern '.text.*', but will not
remove the section '.text.foo'.
- --remove-relocations=sectionpattern
- Remove non-dynamic relocations from the output file for any section
matching sectionpattern. This option may be given more than
once. Note that using this option inappropriately may make the output
file unusable, and attempting to remove a dynamic relocation section
such as ‘.rela.plt’ from an executable or shared library with
--remove-relocations=.plt will not work. Wildcard characters
are accepted in sectionpattern.
For example:
--remove-relocations=.text.*
will remove the relocations for all sections matching the pattern
'.text.*'.
If the first character of sectionpattern is the exclamation
point (!) then matching sections will not have their relocation
removed even if an earlier use of --remove-relocations on the
same command line would otherwise cause the relocations to be removed.
For example:
--remove-relocations=.text.* --remove-relocations=!.text.foo
will remove all relocations for sections matching the pattern
'.text.*', but will not remove relocations for the section
'.text.foo'.
- -S
- --strip-all
- Do not copy relocation and symbol information from the source file.
- -g
- --strip-debug
- Do not copy debugging symbols or sections from the source file.
- --strip-unneeded
- Strip all symbols that are not needed for relocation processing.
- -K symbolname
- --keep-symbol=symbolname
- When stripping symbols, keep symbol symbolname even if it would
normally be stripped. This option may be given more than once.
- -N symbolname
- --strip-symbol=symbolname
- Do not copy symbol symbolname from the source file. This option
may be given more than once.
- --strip-unneeded-symbol=symbolname
- Do not copy symbol symbolname from the source file unless it is needed
by a relocation. This option may be given more than once.
- -G symbolname
- --keep-global-symbol=symbolname
- Keep only symbol symbolname global. Make all other symbols local
to the file, so that they are not visible externally. This option may
be given more than once. Note: this option cannot be used in
conjunction with the --globalize-symbol or
--globalize-symbols options.
- --localize-hidden
- In an ELF object, mark all symbols that have hidden or internal visibility
as local. This option applies on top of symbol-specific localization options
such as -L.
- -L symbolname
- --localize-symbol=symbolname
- Convert a global or weak symbol called symbolname into a local
symbol, so that it is not visible externally. This option may be
given more than once. Note - unique symbols are not converted.
- -W symbolname
- --weaken-symbol=symbolname
- Make symbol symbolname weak. This option may be given more than once.
- --globalize-symbol=symbolname
- Give symbol symbolname global scoping so that it is visible
outside of the file in which it is defined. This option may be given
more than once. Note: this option cannot be used in conjunction with
the -G or --keep-global-symbol options.
- -w
- --wildcard
- Permit regular expressions in symbolnames used in other command
line options. The question mark (?), asterisk (*), backslash (\) and
square brackets ([]) operators can be used anywhere in the symbol
name. If the first character of the symbol name is the exclamation
point (!) then the sense of the switch is reversed for that symbol.
For example:
-w -W !foo -W fo*
would cause objcopy to weaken all symbols that start with “fo”
except for the symbol “foo”.
- -x
- --discard-all
- Do not copy non-global symbols from the source file.
- -X
- --discard-locals
- Do not copy compiler-generated local symbols.
(These usually start with ‘L’ or ‘.’.)
- -b byte
- --byte=byte
- If interleaving has been enabled via the --interleave option
then start the range of bytes to keep at the byteth byte.
byte can be in the range from 0 to breadth-1, where
breadth is the value given by the --interleave option.
- -i [breadth]
- --interleave[=breadth]
- Only copy a range out of every breadth bytes. (Header data is
not affected). Select which byte in the range begins the copy with
the --byte option. Select the width of the range with the
--interleave-width option.
This option is useful for creating files to program rom. It is
typically used with an srec output target. Note that
objcopy will complain if you do not specify the
--byte option as well.
The default interleave breadth is 4, so with --byte set to 0,
objcopy would copy the first byte out of every four bytes
from the input to the output.
- --interleave-width=width
- When used with the --interleave option, copy width
bytes at a time. The start of the range of bytes to be copied is set
by the --byte option, and the extent of the range is set with
the --interleave option.
The default value for this option is 1. The value of width plus
the byte value set by the --byte option must not exceed
the interleave breadth set by the --interleave option.
This option can be used to create images for two 16-bit flashes interleaved
in a 32-bit bus by passing -b 0 -i 4 --interleave-width=2
and -b 2 -i 4 --interleave-width=2 to two objcopy
commands. If the input was '12345678' then the outputs would be
'1256' and '3478' respectively.
- -p
- --preserve-dates
- Set the access and modification dates of the output file to be the same
as those of the input file.
- -D
- --enable-deterministic-archives
- Operate in deterministic mode. When copying archive members
and writing the archive index, use zero for UIDs, GIDs, timestamps,
and use consistent file modes for all files.
If binutils was configured with
--enable-deterministic-archives, then this mode is on by default.
It can be disabled with the ‘-U’ option, below.
- -U
- --disable-deterministic-archives
- Do not operate in deterministic mode. This is the
inverse of the -D option, above: when copying archive members
and writing the archive index, use their actual UID, GID, timestamp,
and file mode values.
This is the default unless binutils was configured with
--enable-deterministic-archives.
- --debugging
- Convert debugging information, if possible. This is not the default
because only certain debugging formats are supported, and the
conversion process can be time consuming.
- --gap-fill val
- Fill gaps between sections with val. This operation applies to
the load address (LMA) of the sections. It is done by increasing
the size of the section with the lower address, and filling in the extra
space created with val.
- --pad-to address
- Pad the output file up to the load address address. This is
done by increasing the size of the last section. The extra space is
filled in with the value specified by --gap-fill (default zero).
- --set-start val
- Set the start address of the new file to val. Not all object file
formats support setting the start address.
- --change-start incr
- --adjust-start incr
- Change the start address by adding incr. Not all object file
formats support setting the start address.
- --change-addresses incr
- --adjust-vma incr
- Change the VMA and LMA addresses of all sections, as well as the start
address, by adding incr. Some object file formats do not permit
section addresses to be changed arbitrarily. Note that this does not
relocate the sections; if the program expects sections to be loaded at a
certain address, and this option is used to change the sections such
that they are loaded at a different address, the program may fail.
- --change-section-address sectionpattern{=,+,-}val
- --adjust-section-vma sectionpattern{=,+,-}val
- Set or change both the VMA address and the LMA address of any section
matching sectionpattern. If ‘=’ is used, the section
address is set to val. Otherwise, val is added to or
subtracted from the section address. See the comments under
--change-addresses, above. If sectionpattern does not
match any sections in the input file, a warning will be issued, unless
--no-change-warnings is used.
- --change-section-lma sectionpattern{=,+,-}val
- Set or change the LMA address of any sections matching
sectionpattern. The LMA address is the address where the
section will be loaded into memory at program load time. Normally
this is the same as the VMA address, which is the address of the
section at program run time, but on some systems, especially those
where a program is held in ROM, the two can be different. If ‘=’
is used, the section address is set to val. Otherwise,
val is added to or subtracted from the section address. See the
comments under --change-addresses, above. If
sectionpattern does not match any sections in the input file, a
warning will be issued, unless --no-change-warnings is used.
- --change-section-vma sectionpattern{=,+,-}val
- Set or change the VMA address of any section matching
sectionpattern. The VMA address is the address where the
section will be located once the program has started executing.
Normally this is the same as the LMA address, which is the address
where the section will be loaded into memory, but on some systems,
especially those where a program is held in ROM, the two can be
different. If ‘=’ is used, the section address is set to
val. Otherwise, val is added to or subtracted from the
section address. See the comments under --change-addresses,
above. If sectionpattern does not match any sections in the
input file, a warning will be issued, unless
--no-change-warnings is used.
- --change-warnings
- --adjust-warnings
- If --change-section-address or --change-section-lma or
--change-section-vma is used, and the section pattern does not
match any sections, issue a warning. This is the default.
- --no-change-warnings
- --no-adjust-warnings
- Do not issue a warning if --change-section-address or
--adjust-section-lma or --adjust-section-vma is used, even
if the section pattern does not match any sections.
- --set-section-flags sectionpattern=flags
- Set the flags for any sections matching sectionpattern. The
flags argument is a comma separated string of flag names. The
recognized names are ‘alloc’, ‘contents’, ‘load’,
‘noload’, ‘readonly’, ‘code’, ‘data’, ‘rom’,
‘share’, and ‘debug’. You can set the ‘contents’ flag
for a section which does not have contents, but it is not meaningful
to clear the ‘contents’ flag of a section which does have
contents–just remove the section instead. Not all flags are
meaningful for all object file formats.
- --add-section sectionname=filename
- Add a new section named sectionname while copying the file. The
contents of the new section are taken from the file filename. The
size of the section will be the size of the file. This option only
works on file formats which can support sections with arbitrary names.
Note - it may be necessary to use the --set-section-flags
option to set the attributes of the newly created section.
- --dump-section sectionname=filename
- Place the contents of section named sectionname into the file
filename, overwriting any contents that may have been there
previously. This option is the inverse of --add-section.
This option is similar to the --only-section option except
that it does not create a formatted file, it just dumps the contents
as raw binary data, without applying any relocations. The option can
be specified more than once.
- --update-section sectionname=filename
- Replace the existing contents of a section named sectionname
with the contents of file filename. The size of the section
will be adjusted to the size of the file. The section flags for
sectionname will be unchanged. For ELF format files the section
to segment mapping will also remain unchanged, something which is not
possible using --remove-section followed by
--add-section. The option can be specified more than once.
Note - it is possible to use --rename-section and
--update-section to both update and rename a section from one
command line. In this case, pass the original section name to
--update-section, and the original and new section names to
--rename-section.
- --add-symbol name=[section:]value[,flags]
- Add a new symbol named name while copying the file. This option may be
specified multiple times. If the section is given, the symbol will be
associated with and relative to that section, otherwise it will be an ABS
symbol. Specifying an undefined section will result in a fatal error. There
is no check for the value, it will be taken as specified. Symbol flags can
be specified and not all flags will be meaningful for all object file
formats. By default, the symbol will be global. The special flag
'before=othersym' will insert the new symbol in front of the specified
othersym, otherwise the symbol(s) will be added at the end of the
symbol table in the order they appear.
- --rename-section oldname=newname[,flags]
- Rename a section from oldname to newname, optionally
changing the section's flags to flags in the process. This has
the advantage over using a linker script to perform the rename in that
the output stays as an object file and does not become a linked
executable.
This option is particularly helpful when the input format is binary,
since this will always create a section called .data. If for example,
you wanted instead to create a section called .rodata containing binary
data you could use the following command line to achieve it:
objcopy -I binary -O <output_format> -B <architecture> \
--rename-section .data=.rodata,alloc,load,readonly,data,contents \
<input_binary_file> <output_object_file>
- --long-section-names {enable,disable,keep}
- Controls the handling of long section names when processing
COFF
and PE-COFF object formats. The default behaviour, ‘keep’,
is to preserve long section names if any are present in the input file.
The ‘enable’ and ‘disable’ options forcibly enable or disable
the use of long section names in the output object; when ‘disable’
is in effect, any long section names in the input object will be truncated.
The ‘enable’ option will only emit long section names if any are
present in the inputs; this is mostly the same as ‘keep’, but it
is left undefined whether the ‘enable’ option might force the
creation of an empty string table in the output file.
- --change-leading-char
- Some object file formats use special characters at the start of
symbols. The most common such character is underscore, which compilers
often add before every symbol. This option tells objcopy to
change the leading character of every symbol when it converts between
object file formats. If the object file formats use the same leading
character, this option has no effect. Otherwise, it will add a
character, or remove a character, or change a character, as
appropriate.
- --remove-leading-char
- If the first character of a global symbol is a special symbol leading
character used by the object file format, remove the character. The
most common symbol leading character is underscore. This option will
remove a leading underscore from all global symbols. This can be useful
if you want to link together objects of different file formats with
different conventions for symbol names. This is different from
--change-leading-char because it always changes the symbol name
when appropriate, regardless of the object file format of the output
file.
- --reverse-bytes=num
- Reverse the bytes in a section with output contents. A section length must
be evenly divisible by the value given in order for the swap to be able to
take place. Reversing takes place before the interleaving is performed.
This option is used typically in generating ROM images for problematic
target systems. For example, on some target boards, the 32-bit words
fetched from 8-bit ROMs are re-assembled in little-endian byte order
regardless of the CPU byte order. Depending on the programming model, the
endianness of the ROM may need to be modified.
Consider a simple file with a section containing the following eight
bytes: 12345678.
Using ‘--reverse-bytes=2’ for the above example, the bytes in the
output file would be ordered 21436587.
Using ‘--reverse-bytes=4’ for the above example, the bytes in the
output file would be ordered 43218765.
By using ‘--reverse-bytes=2’ for the above example, followed by
‘--reverse-bytes=4’ on the output file, the bytes in the second
output file would be ordered 34127856.
- --srec-len=ival
- Meaningful only for srec output. Set the maximum length of the Srecords
being produced to ival. This length covers both address, data and
crc fields.
- --srec-forceS3
- Meaningful only for srec output. Avoid generation of S1/S2 records,
creating S3-only record format.
- --redefine-sym old=new
- Change the name of a symbol old, to new. This can be useful
when one is trying link two things together for which you have no
source, and there are name collisions.
- --redefine-syms=filename
- Apply --redefine-sym to each symbol pair "old new"
listed in the file filename. filename is simply a flat file,
with one symbol pair per line. Line comments may be introduced by the hash
character. This option may be given more than once.
- --weaken
- Change all global symbols in the file to be weak. This can be useful
when building an object which will be linked against other objects using
the -R option to the linker. This option is only effective when
using an object file format which supports weak symbols.
- --keep-symbols=filename
- Apply --keep-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol
name per line. Line comments may be introduced by the hash character.
This option may be given more than once.
- --strip-symbols=filename
- Apply --strip-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol
name per line. Line comments may be introduced by the hash character.
This option may be given more than once.
- --strip-unneeded-symbols=filename
- Apply --strip-unneeded-symbol option to each symbol listed in
the file filename. filename is simply a flat file, with one
symbol name per line. Line comments may be introduced by the hash
character. This option may be given more than once.
- --keep-global-symbols=filename
- Apply --keep-global-symbol option to each symbol listed in the
file filename. filename is simply a flat file, with one
symbol name per line. Line comments may be introduced by the hash
character. This option may be given more than once.
- --localize-symbols=filename
- Apply --localize-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol
name per line. Line comments may be introduced by the hash character.
This option may be given more than once.
- --globalize-symbols=filename
- Apply --globalize-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol
name per line. Line comments may be introduced by the hash character.
This option may be given more than once. Note: this option cannot be
used in conjunction with the -G or --keep-global-symbol
options.
- --weaken-symbols=filename
- Apply --weaken-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol
name per line. Line comments may be introduced by the hash character.
This option may be given more than once.
- --alt-machine-code=index
- If the output architecture has alternate machine codes, use the
indexth code instead of the default one. This is useful in case
a machine is assigned an official code and the tool-chain adopts the
new code, but other applications still depend on the original code
being used. For ELF based architectures if the index
alternative does not exist then the value is treated as an absolute
number to be stored in the e_machine field of the ELF header.
- --writable-text
- Mark the output text as writable. This option isn't meaningful for all
object file formats.
- --readonly-text
- Make the output text write protected. This option isn't meaningful for all
object file formats.
- --pure
- Mark the output file as demand paged. This option isn't meaningful for all
object file formats.
- --impure
- Mark the output file as impure. This option isn't meaningful for all
object file formats.
- --prefix-symbols=string
- Prefix all symbols in the output file with string.
- --prefix-sections=string
- Prefix all section names in the output file with string.
- --prefix-alloc-sections=string
- Prefix all the names of all allocated sections in the output file with
string.
- --add-gnu-debuglink=path-to-file
- Creates a .gnu_debuglink section which contains a reference to
path-to-file and adds it to the output file. Note: the file at
path-to-file must exist. Part of the process of adding the
.gnu_debuglink section involves embedding a checksum of the contents
of the debug info file into the section.
If the debug info file is built in one location but it is going to be
installed at a later time into a different location then do not use
the path to the installed location. The --add-gnu-debuglink
option will fail because the installed file does not exist yet.
Instead put the debug info file in the current directory and use the
--add-gnu-debuglink option without any directory components,
like this:
objcopy --add-gnu-debuglink=foo.debug
At debug time the debugger will attempt to look for the separate debug
info file in a set of known locations. The exact set of these
locations varies depending upon the distribution being used, but it
typically includes:
* The same directory as the executable.
* A sub-directory of the directory containing the executable- called .debug
* A global debug directory such as /usr/lib/debug.
As long as the debug info file has been installed into one of these
locations before the debugger is run everything should work
correctly.
- --keep-file-symbols
- When stripping a file, perhaps with --strip-debug or
--strip-unneeded, retain any symbols specifying source file names,
which would otherwise get stripped.
- --only-keep-debug
- Strip a file, removing contents of any sections that would not be
stripped by --strip-debug and leaving the debugging sections
intact. In ELF files, this preserves all note sections in the output.
Note - the section headers of the stripped sections are preserved,
including their sizes, but the contents of the section are discarded.
The section headers are preserved so that other tools can match up the
debuginfo file with the real executable, even if that executable has
been relocated to a different address space.
The intention is that this option will be used in conjunction with
--add-gnu-debuglink to create a two part executable. One a
stripped binary which will occupy less space in RAM and in a
distribution and the second a debugging information file which is only
needed if debugging abilities are required. The suggested procedure
to create these files is as follows:
- Link the executable as normal. Assuming that it is called
foo then...
- Run
objcopy --only-keep-debug foo foo.dbg to
create a file containing the debugging info.
- Run
objcopy --strip-debug foo to create a
stripped executable.
- Run
objcopy --add-gnu-debuglink=foo.dbg foo
to add a link to the debugging info into the stripped executable.
Note—the choice of .dbg as an extension for the debug info
file is arbitrary. Also the --only-keep-debug step is
optional. You could instead do this:
- Link the executable as normal.
- Copy
foo to foo.full
- Run
objcopy --strip-debug foo
- Run
objcopy --add-gnu-debuglink=foo.full foo
i.e., the file pointed to by the --add-gnu-debuglink can be the
full executable. It does not have to be a file created by the
--only-keep-debug switch.
Note—this switch is only intended for use on fully linked files. It
does not make sense to use it on object files where the debugging
information may be incomplete. Besides the gnu_debuglink feature
currently only supports the presence of one filename containing
debugging information, not multiple filenames on a one-per-object-file
basis.
- --strip-dwo
- Remove the contents of all DWARF .dwo sections, leaving the
remaining debugging sections and all symbols intact.
This option is intended for use by the compiler as part of
the -gsplit-dwarf option, which splits debug information
between the .o file and a separate .dwo file. The compiler
generates all debug information in the same file, then uses
the --extract-dwo option to copy the .dwo sections to
the .dwo file, then the --strip-dwo option to remove
those sections from the original .o file.
- --extract-dwo
- Extract the contents of all DWARF .dwo sections. See the
--strip-dwo option for more information.
- --file-alignment num
- Specify the file alignment. Sections in the file will always begin at
file offsets which are multiples of this number. This defaults to
512.
[This option is specific to PE targets.]
- --heap reserve
- --heap reserve,commit
- Specify the number of bytes of memory to reserve (and optionally commit)
to be used as heap for this program.
[This option is specific to PE targets.]
- --image-base value
- Use value as the base address of your program or dll. This is
the lowest memory location that will be used when your program or dll
is loaded. To reduce the need to relocate and improve performance of
your dlls, each should have a unique base address and not overlap any
other dlls. The default is 0x400000 for executables, and 0x10000000
for dlls.
[This option is specific to PE targets.]
- --section-alignment num
- Sets the section alignment. Sections in memory will always begin at
addresses which are a multiple of this number. Defaults to 0x1000.
[This option is specific to PE targets.]
- --stack reserve
- --stack reserve,commit
- Specify the number of bytes of memory to reserve (and optionally commit)
to be used as stack for this program.
[This option is specific to PE targets.]
- --subsystem which
- --subsystem which:major
- --subsystem which:major.minor
- Specifies the subsystem under which your program will execute. The
legal values for which are
native, windows,
console, posix, efi-app, efi-bsd,
efi-rtd, sal-rtd, and xbox. You may optionally set
the subsystem version also. Numeric values are also accepted for
which.
[This option is specific to PE targets.]
- --extract-symbol
- Keep the file's section flags and symbols but remove all section data.
Specifically, the option:
- removes the contents of all sections;
- sets the size of every section to zero; and
- sets the file's start address to zero.
This option is used to build a .sym file for a VxWorks kernel.
It can also be a useful way of reducing the size of a --just-symbols
linker input file.
- --compress-debug-sections
- Compress DWARF debug sections using zlib with SHF_COMPRESSED from the
ELF ABI. Note - if compression would actually make a section
larger, then it is not compressed.
- --compress-debug-sections=none
- --compress-debug-sections=zlib
- --compress-debug-sections=zlib-gnu
- --compress-debug-sections=zlib-gabi
- For ELF files, these options control how DWARF debug sections are
compressed. --compress-debug-sections=none is equivalent
to --decompress-debug-sections.
--compress-debug-sections=zlib and
--compress-debug-sections=zlib-gabi are equivalent to
--compress-debug-sections.
--compress-debug-sections=zlib-gnu compresses DWARF debug
sections using zlib. The debug sections are renamed to begin with
‘.zdebug’ instead of ‘.debug’. Note - if compression would
actually make a section larger, then it is not compressed nor
renamed.
- --decompress-debug-sections
- Decompress DWARF debug sections using zlib. The original section
names of the compressed sections are restored.
- --elf-stt-common=yes
- --elf-stt-common=no
- For ELF files, these options control whether common symbols should be
converted to the
STT_COMMON or STT_OBJECT type.
--elf-stt-common=yes converts common symbol type to
STT_COMMON. --elf-stt-common=no converts common symbol
type to STT_OBJECT.
- --merge-notes
- --no-merge-notes
- For ELF files, attempt (or do not attempt) to reduce the size of any
SHT_NOTE type sections by removing duplicate notes.
- -V
- --version
- Show the version number of objcopy.
- -v
- --verbose
- Verbose output: list all object files modified. In the case of
archives, ‘objcopy -V’ lists all members of the archive.
- --help
- Show a summary of the options to objcopy.
- --info
- Display a list showing all architectures and object formats available.