objcopy(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COPYRIGHT | COLOPHON

OBJCOPY(1)                GNU Development Tools               OBJCOPY(1)

NAME         top

       objcopy - copy and translate object files

SYNOPSIS         top

       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]
               [--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]
               [-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]
               [--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]
               [--verilog-data-width=val]
               [-v|--verbose]
               [-V|--version]
               [--help] [--info]
               infile [outfile]

DESCRIPTION         top

       The GNU objcopy utility copies the contents of an object file to
       another.  objcopy uses the GNU BFD Library to read and write the
       object files.  It can write the destination object file in a
       format different from that of the source object file.  The exact
       behavior of objcopy is controlled by command-line options.  Note
       that objcopy should be able to copy a fully linked file between
       any two formats. However, copying a relocatable object file
       between any two formats may not work as expected.

       objcopy creates temporary files to do its translations and
       deletes them afterward.  objcopy uses BFD to do all its
       translation work; it has access to all the formats described in
       BFD and thus is able to recognize most formats without being told
       explicitly.

       objcopy can be used to generate S-records by using an output
       target of srec (e.g., use -O srec).

       objcopy can be used to generate a raw binary file by using an
       output target of binary (e.g., use -O binary).  When objcopy
       generates a raw binary file, it will essentially produce a memory
       dump of the contents of the input object file.  All symbols and
       relocation information will be discarded.  The memory dump will
       start at the load address of the lowest section copied into the
       output file.

       When generating an S-record or a raw binary file, it may be
       helpful to use -S to remove sections containing debugging
       information.  In some cases -R will be useful to remove sections
       which contain information that is not needed by the binary file.

       Note---objcopy is not able to change the endianness of its input
       files.  If the input format has an endianness (some formats do
       not), objcopy can only copy the inputs into file formats that
       have the same endianness or which have no endianness (e.g.,
       srec).  (However, see the --reverse-bytes option.)

OPTIONS         top

       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'.

       -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.

       -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, 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.

       --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 --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.
           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-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
           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.

       --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.

SEE ALSO         top

       ld(1), objdump(1), and the Info entries for binutils.

COPYRIGHT         top

       Copyright (c) 1991-2021 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".

COLOPHON         top

       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-2.36.1.tar.gz
       fetched from ⟨https://ftp.gnu.org/gnu/binutils/⟩ on 2021-04-01.
       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 man-pages@man7.org

binutils-2.36.1                2021-02-06                     OBJCOPY(1)

Pages that refer to this page: ld(1)elf(5)