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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COPYRIGHT | COLOPHON |
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OBJCOPY(1) GNU Development Tools OBJCOPY(1)
objcopy - copy and translate object files
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]
[--strip-unneeded]
[-K symbolname|--keep-symbol=symbolname]
[--keep-file-symbols]
[--keep-section-symbols]
[-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]
[--globalize-symbols=filename]
[-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]
[--keep-section=sectionpattern]
[--remove-relocations=sectionpattern]
[--strip-section-headers]
[-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]
[--set-section-alignment sectionpattern=align]
[--add-section sectionname=filename]
[--dump-section sectionname=filename]
[--update-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]
[--weaken-symbols=filename]
[--add-symbol name=[section:]value[,flags]]
[--alt-machine-code=index]
[--prefix-symbols=string]
[--prefix-sections=string]
[--prefix-alloc-sections=string]
[--add-gnu-debuglink=path-to-file]
[--only-keep-debug]
[--strip-dwo]
[--extract-dwo]
[--extract-symbol]
[--writable-text]
[--readonly-text]
[--pure]
[--impure]
[--file-alignment=num]
[--heap=reserve[,commit]]
[--image-base=address]
[--section-alignment=num]
[--stack=reserve[,commit]]
[--subsystem=which:major.minor]
[--compress-debug-sections]
[--decompress-debug-sections]
[--elf-stt-common=val]
[--merge-notes]
[--no-merge-notes]
[--verilog-data-width=val]
[-v|--verbose]
[-V|--version]
[--help] [--info]
infile [outfile]
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.)
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 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 matching '.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'.
--keep-section=sectionpattern
When removing sections from the output file, keep sections
that match sectionpattern.
--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'.
--strip-section-headers
Strip section header This option is specific to ELF files.
Implies --strip-all and --merge-notes.
-S
--strip-all
Do not copy relocation and symbol information from the source
file. Also deletes debug sections.
-g
--strip-debug
Do not copy debugging symbols or sections from the source
file.
--strip-unneeded
Remove all symbols that are not needed for relocation
processing in addition to debugging symbols and sections
stripped by --strip-debug.
-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.
This option also copies the date stored in a PE format file's
header, unless the SOURCE_DATE_EPOCH environment variable is
defined. If it is defined then this variable will be used as
the date stored in the header, interpreted as the number of
seconds since the Unix epoch.
-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 (also known as the entry 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 (also known as the entry 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, exclude, share, debug, and large.
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. In particular the share flag is only
meaningful for COFF format files and not for ELF format
files. The ELF x86-64 specific flag large corresponds to
SHF_X86_64_LARGE.
--set-section-alignment sectionpattern=align
Set the alignment for any sections matching sectionpattern.
align specifies the alignment in bytes and must be a power of
two, i.e. 1, 2, 4, 8....
--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 accepts the same set of flags
as the --set-section-flags option.
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-section-symbils
When stripping a file, perhaps with --strip-debug or
--strip-unneeded, retain any symbols specifying section
names, which would otherwise get stripped.
--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:
1.<Link the executable as normal. Assuming that it 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.
--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 field in the PE header. 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
--compress-debug-sections=zstd
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 the obsoleted zlib-gnu format. The debug
sections are renamed to begin with .zdebug.
--compress-debug-sections=zstd compresses DWARF debug
sections using zstd. Note - if compression would actually
make a section larger, then it is not compressed nor renamed.
--decompress-debug-sections
Decompress DWARF debug sections. For a .zdebug section, the
original name is 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.
--verilog-data-width=bytes
For Verilog output, this options controls the number of bytes
converted for each output data element. The input target
controls the endianness of the conversion.
-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.
ld(1), objdump(1), and the Info entries for binutils.
Copyright (c) 1991-2024 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".
This page is part of the binutils (a collection of tools for
working with executable binaries) project. Information about the
project can be found at ⟨http://www.gnu.org/software/binutils/⟩.
If you have a bug report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=binutils⟩.
This page was obtained from the tarball binutils-2.42.tar.gz
fetched from ⟨https://ftp.gnu.org/gnu/binutils/⟩ on 2024-06-14.
If you discover any rendering problems in this HTML version of
the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to
the information in this COLOPHON (which is not part of the
original manual page), send a mail to [email protected]
binutils-2.42 2024-06-14 OBJCOPY(1)
Pages that refer to this page: ld(1), elf(5)
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