File: binutils.info, Node: objcopy, Next: objdump, Prev: nm, Up: Top
3 objcopy
*********
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. *Note BFD:
(ld.info)BFD.
'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. *Note Target Selection::, for more
information.
'-O BFDNAME'
'--output-target=BFDNAME'
Write the output file using the object format BFDNAME. *Note
Target Selection::, for more information.
'-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. *Note Target Selection::, for more information.
'-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 maching '.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. In particular the
'share' flag is only meaningful for COFF format files and not for
ELF format files.
'--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
'--sect-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.
'--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 is is called
'foo' then...
2. Run 'objcopy --only-keep-debug foo foo.dbg' to create a file
containing the debugging info.
3. Run 'objcopy --strip-debug foo' to create a stripped
executable.
4. 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.
2. Copy 'foo' to 'foo.full'
3. Run 'objcopy --strip-debug foo'
4. 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. 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'
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.
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