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]
[-N symbolname|--strip-symbol=symbolname]
[--strip-unneeded-symbol=symbolname]
[-G symbolname|--keep-global-symbol=symbolname]
[--localize-hidden]
[-L symbolname|--localize-symbol=symbolname]
[--globalize-symbol=symbolname]
[-W symbolname|--weaken-symbol=symbolname]
[-w|--wildcard]
[-x|--discard-all]
[-X|--discard-locals]
[-b byte|--byte=byte]
[-i [breadth]|--interleave[=breadth]]
[--interleave-width=width]
[-j sectionpattern|--only-section=sectionpattern]
[-R
sectionpattern|--remove-section=sectionpattern]
[--remove-relocations=sectionpattern]
[-p|--preserve-dates]
[-D|--enable-deterministic-archives]
[-U|--disable-deterministic-archives]
[--debugging]
[--gap-fill=val]
[--pad-to=address]
[--set-start=val]
[--adjust-start=incr]
[--change-addresses=incr]
[--change-section-address sectionpattern{=,+,-}val]
[--change-section-lma sectionpattern{=,+,-}val]
[--change-section-vma sectionpattern{=,+,-}val]
[--change-warnings] [--no-change-warnings]
[--set-section-flags sectionpattern=flags]
[--add-section sectionname=filename]
[--dump-section sectionname=filename]
[--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]
[--globalize-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]
[--keep-file-symbols]
[--only-keep-debug]
[--strip-dwo]
[--extract-dwo]
[--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]
[--compress-debug-sections]
[--decompress-debug-sections]
[--elf-stt-common=val]
[--merge-notes]
[--no-merge-notes]
[-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'.
- --remove-relocations=sectionpattern
- Remove 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.
Wildcard characters are accepted in sectionpattern. For example:
--remove-relocations=.text.*
will remove the relocations for all sections matching the
patter '.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'.
- -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
- 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.
- -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.
- -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 of the new file to val. Not all object file
formats support setting the start address.
- --change-start
incr
- --adjust-start
incr
- Change the start address by adding incr. Not all object file
formats support setting the start address.
- --change-addresses
incr
- --adjust-vma
incr
- Change the VMA and LMA addresses of all sections, as well as the start
address, by adding incr. Some object file formats do not permit
section addresses to be changed arbitrarily. Note that this does not
relocate the sections; if the program expects sections to be loaded at a
certain address, and this option is used to change the sections such that
they are loaded at a different address, the program may fail.
- --change-section-address
sectionpattern{=,+,-}val
- --adjust-section-vma
sectionpattern{=,+,-}val
- Set or change both the VMA address and the LMA address of any section
matching sectionpattern. If = is used, the section address
is set to val. Otherwise, val is added to or subtracted from
the section address. See the comments under --change-addresses,
above. If sectionpattern does not match any sections in the input
file, a warning will be issued, unless --no-change-warnings is
used.
- --change-section-lma
sectionpattern{=,+,-}val
- Set or change the LMA address of any sections matching
sectionpattern. The LMA address is the address where the section
will be loaded into memory at program load time. Normally this is the same
as the VMA address, which is the address of the section at program run
time, but on some systems, especially those where a program is held in
ROM, the two can be different. If = is used, the section address is
set to val. Otherwise, val is added to or subtracted from
the section address. See the comments under --change-addresses,
above. If sectionpattern does not match any sections in the input
file, a warning will be issued, unless --no-change-warnings is
used.
- --change-section-vma
sectionpattern{=,+,-}val
- Set or change the VMA address of any section matching
sectionpattern. The VMA address is the address where the section
will be located once the program has started executing. Normally this is
the same as the LMA address, which is the address where the section will
be loaded into memory, but on some systems, especially those where a
program is held in ROM, the two can be different. If = is used, the
section address is set to val. Otherwise, val is added to or
subtracted from the section address. See the comments under
--change-addresses, above. If sectionpattern does not match
any sections in the input file, a warning will be issued, unless
--no-change-warnings is used.
- --change-warnings
- --adjust-warnings
- 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,
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. 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 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. 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-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 the contents of all DWARF .dwo sections. See the
--strip-dwo option for more information.
- --file-alignment
num
- Specify the file alignment. Sections in the file will always begin at file
offsets which are multiples of this number. This defaults to 512. [This
option is specific to PE targets.]
- --heap
reserve
- --heap
reserve,commit
- Specify the number of bytes of memory to reserve (and optionally commit)
to be used as heap for this program. [This option is specific to PE
targets.]
- --image-base
value
- Use value as the base address of your program or dll. This is the
lowest memory location that will be used when your program or dll is
loaded. To reduce the need to relocate and improve performance of your
dlls, each should have a unique base address and not overlap any other
dlls. The default is 0x400000 for executables, and 0x10000000 for dlls.
[This option is specific to PE targets.]
- --section-alignment
num
- Sets the section alignment. Sections in memory will always begin at
addresses which are a multiple of this number. Defaults to 0x1000. [This
option is specific to PE targets.]
- --stack
reserve
- --stack
reserve,commit
- Specify the number of bytes of memory to reserve (and optionally commit)
to be used as stack for this program. [This option is specific to PE
targets.]
- --subsystem
which
- --subsystem
which:major
- --subsystem
which:major.minor
- Specifies the subsystem under which your program will execute. The legal
values for which are "native",
"windows",
"console",
"posix",
"efi-app",
"efi-bsd",
"efi-rtd",
"sal-rtd", and
"xbox". You may optionally set the
subsystem version also. Numeric values are also accepted for which.
[This option is specific to PE targets.]
- 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
- 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 zlib. The debug sections are renamed to begin with .zdebug
instead of .debug. Note - if compression would actually make a
section larger, then it is not compressed nor renamed.
- --decompress-debug-sections
- Decompress DWARF debug sections using zlib. The original section names of
the compressed sections are 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.
- -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.
Copyright (c) 1991-2018 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".