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 raw binary 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 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".