OBJCOPY(1) GNU Development Tools OBJCOPY(1)
NAME
objcopy - copy and translate object files
SYNOPSIS
objcopy [-F bfdname|--target=bfdname]
[-I bfdname|--input-target=bfdname]
[-O bfdname|--output-target=bfdname]
[-B bfdarch|--binary-architecture=bfdarch]
[-S|--strip-all]
[-g|--strip-debug]
[-K symbolname|--keep-symbol=symbolname]
[-N symbolname|--strip-symbol=symbolname]
[--strip-unneeded-symbol=symbolname]
[-G symbolname|--keep-global-symbol=symbolname]
[--localize-hidden]
[-L symbolname|--localize-symbol=symbolname]
[--globalize-symbol=symbolname]
[-W symbolname|--weaken-symbol=symbolname]
[-w|--wildcard]
[-x|--discard-all]
[-X|--discard-locals]
[-b byte|--byte=byte]
[-i [breadth]|--interleave[=breadth]]
[--interleave-width=width]
[-j sectionpattern|--only-section=sectionpattern]
[-R sectionpattern|--remove-section=sectionpattern]
[-p|--preserve-dates]
[-D|--enable-deterministic-archives]
[-U|--disable-deterministic-archives]
[--debugging]
[--gap-fill=val]
[--pad-to=address]
[--set-start=val]
[--adjust-start=incr]
[--change-addresses=incr]
[--change-section-address sectionpattern{=,+,-}val]
[--change-section-lma sectionpattern{=,+,-}val]
[--change-section-vma sectionpattern{=,+,-}val]
[--change-warnings] [--no-change-warnings]
[--set-section-flags sectionpattern=flags]
[--add-section sectionname=filename]
[--dump-section sectionname=filename]
[--rename-section oldname=newname[,flags]]
[--long-section-names {enable,disable,keep}]
[--change-leading-char] [--remove-leading-char]
[--reverse-bytes=num]
[--srec-len=ival] [--srec-forceS3]
[--redefine-sym old=new]
[--redefine-syms=filename]
[--weaken]
[--keep-symbols=filename]
[--strip-symbols=filename]
[--strip-unneeded-symbols=filename]
[--keep-global-symbols=filename]
[--localize-symbols=filename]
[--globalize-symbols=filename]
[--readonly-text]
[--pure]
[--impure]
[--file-alignment=num]
[--heap=size]
[--image-base=address]
[--section-alignment=num]
[--stack=size]
[--subsystem=which:major.minor]
[--compress-debug-sections]
[--decompress-debug-sections]
[--dwarf-depth=n]
[--dwarf-start=n]
[-v|--verbose]
[-V|--version]
[--help] [--info]
infile [outfile]
DESCRIPTION
The GNU objcopy utility copies the contents of an object file to another. objcopy uses the GNU BFD Library to
read and write the object files. It can write the destination object file in a format different from that of
the source object file. The exact behavior of objcopy is controlled by command-line options. Note that
objcopy should be able to copy a fully linked file between any two formats. However, copying a relocatable
object file between any two formats may not work as expected.
objcopy creates temporary files to do its translations and deletes them afterward. objcopy uses BFD to do all
its translation work; it has access to all the formats described in BFD and thus is able to recognize most
formats without being told explicitly.
objcopy can be used to generate S-records by using an output target of srec (e.g., use -O srec).
objcopy can be used to generate a raw binary file by using an output target of binary (e.g., use -O binary).
When objcopy generates a raw binary file, it will essentially produce a memory dump of the contents of the
input object file. All symbols and relocation information will be discarded. The memory dump will start at
the load address of the lowest section copied into the output file.
When generating an S-record or a raw binary file, it may be helpful to use -S to remove sections containing
debugging information. In some cases -R will be useful to remove sections which contain information that is
not needed by the binary file.
Note---objcopy is not able to change the endianness of its input files. If the input format has an endianness
(some formats do not), objcopy can only copy the inputs into file formats that have the same endianness or
which have no endianness (e.g., srec). (However, see the --reverse-bytes option.)
OPTIONS
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.
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.
-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.
-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.
--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
Make symbol symbolname local to the file, so that it is not visible externally. This option may be given
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.
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
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.
--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 usng 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
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
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.
--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.
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:
1.<Link the executable as normal. Assuming that is is called>
"foo" then...
1.<Run "objcopy --only-keep-debug foo foo.dbg" to>
create a file containing the debugging info.
1.<Run "objcopy --strip-debug foo" to create a>
stripped executable.
1.<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:
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.
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.
@file
Read command-line options from file. The options read are inserted in place of the original @file option.
If file does not exist, or cannot be read, then the option will be treated literally, and not removed.
Options in file are separated by whitespace. A whitespace character may be included in an option by
surrounding the entire option in either single or double quotes. Any character (including a backslash)
may be included by prefixing the character to be included with a backslash. The file may itself contain
additional @file options; any such options will be processed recursively.
SEE ALSO
ld(1), objdump(1), and the Info entries for binutils.
COPYRIGHT
Copyright (c) 1991-2014 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free
Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is
included in the section entitled "GNU Free Documentation License".
binutils-2.25 2014-12-23 OBJCOPY(1)
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