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 (eg srec).
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.
-Ibfdname
--input-target=bfdname
Consider the source file's object format to be bfdname, rather than
attempting to deduce it.
-Obfdname
--output-target=bfdname
Write the output file using the object format bfdname.
-Fbfdname
--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.
-Bbfdarch
--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.
-jsectionname
--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.
-Rsectionname
--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 from the source file.
--strip-unneeded
Strip all symbols that are not needed for relocation processing.
-Ksymbolname
--keep-symbol=symbolname
Copy only symbol symbolname from the source file. This option may
be given more than once.
-Nsymbolname
--strip-symbol=symbolname
Do not copy symbol symbolname from the source file. This option
may be given more than once.
-Gsymbolname
--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.
-Lsymbolname
--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.
-Wsymbolname
--weaken-symbol=symbolname
Make symbol symbolname weak. This option may be given more than once.
-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 ..)
-bbyte
--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.
-iinterleave
--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-fillval
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-toaddress
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-startval
Set the start address of the new file to val. Not all object file
formats support setting the start address.
--change-startincr
--adjust-startincr
Change the start address by adding incr. Not all object file
formats support setting the start address.
--change-addressesincr
--adjust-vmaincr
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-addresssection{=,+,-}val
--adjust-section-vmasection{=,+,-}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-lmasection{=,+,-}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-vmasection{=,+,-}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-flagssection=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-sectionsectionname=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-sectionoldname=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:
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.
--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-symold=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.
--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.
--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.
--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.
-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.
SEE ALSO
ld(1), objdump(1), and the Info entries for binutils.
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under the terms of the GNU Free Documentation License, Version 1.1
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''.