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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 interleave|--interleave=interleave]
[-j sectionname|--only-section=sectionname]
[-R sectionname|--remove-section=sectionname]
[-p|--preserve-dates]
[--debugging]
[--gap-fill=val]
[--pad-to=address]
[--set-start=val]
[--adjust-start=incr]
[--change-addresses=incr]
[--change-section-address section{=,+,-}val]
[--change-section-lma section{=,+,-}val]
[--change-section-vma section{=,+,-}val]
[--change-warnings] [--no-change-warnings]
[--set-section-flags section=flags]
[--add-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]
[--weaken-symbols=filename]
[--alt-machine-code=index]
[--prefix-symbols=string]
[--prefix-sections=string]
[--prefix-alloc-sections=string]
[--add-gnu-debuglink=path-to-file]
[--keep-file-symbols]
[--only-keep-debug]
[--extract-symbol]
[--writable-text]
[--readonly-text]
[--pure]
[--impure]
[--file-alignment=num]
[--heap=size]
[--image-base=address]
[--section-alignment=num]
[--stack=size]
[--subsystem=which:major.minor]
[-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.
-O bfdname
--output-target=bfdname
Write the output file using the object format bfdname.
-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.
-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 sectionname
--only-section=sectionname
Copy only the named section 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.
-R sectionname
--remove-section=sectionname
Remove any section named sectionname from the output file. This option may be given more than once. Note that using
this option inappropriately may make the output file unusable.
-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 more than
once.
-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.
-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
Keep only every byteth byte of the input file (header data is not affected). byte can be in the range from 0 to
interleave-1, where interleave is given by the -i or --interleave option, or the default of 4. This option is useful
for creating files to program ROM. It is typically used with an "srec" output target.
-i interleave
--interleave=interleave
Only copy one out of every interleave bytes. Select which byte to copy with the -b or --byte option. The default is
4. objcopy ignores this option if you do not specify either -b or --byte.
-p
--preserve-dates
Set the access and modification dates of the output file to be the same as those of the input file.
--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 section{=,+,-}val
--adjust-section-vma section{=,+,-}val
Set or change both the VMA address and the LMA address of the named section. 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 section does not exist in the input file, a warning will be issued, unless
--no-change-warnings is used.
--change-section-lma section{=,+,-}val
Set or change the LMA address of the named section. 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 section does not exist in the input file, a warning will be
issued, unless --no-change-warnings is used.
--change-section-vma section{=,+,-}val
Set or change the VMA address of the named section. 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 section does not exist 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 named section does not
exist, 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 named section does not exist.
--set-section-flags section=flags
Set the flags for the named section. 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.
--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 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.
--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.
--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:
1.<Link the executable as normal.>
1.<Copy "foo" to "foo.full">
1.<Run "objcopy --strip-debug foo">
1.<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.
--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.
-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.
@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, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
2009, 2010 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-2.20.51.0.7 2011-05-02 OBJCOPY(1)
