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MAN page from RedHat EL 6 toolchain-armiwmmx-2012-2012.12.1-oselas.2.2.x86_64.rpm

OBJCOPY

Section: GNU Development Tools (1)
Updated: 2017-09-21
Index 

NAME

objcopy - copy and translate object files 

SYNOPSIS

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]
        [-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 sectionname|--only-section=sectionname]
        [-R sectionname|--remove-section=sectionname]
        [-p|--preserve-dates]
        [--debugging]
        [--gap-fill=val]
        [--pad-to=address]
        [--set-start=val]
        [--adjust-start=incr]
        [--change-addresses=incr]
        [--change-section-address section{=,+,-}val]
        [--change-section-lma section{=,+,-}val]
        [--change-section-vma section{=,+,-}val]
        [--change-warnings] [--no-change-warnings]
        [--set-section-flags section=flags]
        [--add-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]
        [--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]
        [--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]
        [-v|--verbose]
        [-V|--version]
        [--help] [--info]
        infile [outfile] 

DESCRIPTION

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

objcopy creates temporary files to do its translations anddeletes them afterward. objcopy uses BFD to do all itstranslation work; it has access to all the formats described in BFDand thus is able to recognize most formats without being toldexplicitly.

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

objcopy can be used to generate a raw binary file by using anoutput target of binary (e.g., use -O binary). Whenobjcopy generates a raw binary file, it will essentially producea memory dump of the contents of the input object file. All symbols andrelocation information will be discarded. The memory dump will start atthe 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 touse -S to remove sections containing debugging information. Insome cases -R will be useful to remove sections which containinformation that is not needed by the binary file.

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

OPTIONS

infile
outfile
The input and output files, respectively.If you do not specify outfile, objcopy creates atemporary file and destructively renames the result withthe name of infile.
-I bfdname
--input-target=bfdname
Consider the source file's object format to be bfdname, rather thanattempting 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 outputfile; i.e., simply transfer data from source to destination with notranslation.
-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. Thisoption will be ignored if the input file has a known bfdarch. Youcan access this binary data inside a program by referencing the specialsymbols that are created by the conversion process. These symbols arecalled _binary_objfile_start, _binary_objfile_end and_binary_objfile_size. e.g. you can transform a picture file intoan object file and then access it in your code using these symbols.
-j sectionname
--only-section=sectionname
Copy only the named section from the input file to the output file.This option may be given more than once. Note that using this optioninappropriately may make the output file unusable.
-R sectionname
--remove-section=sectionname
Remove any section named sectionname from the output file. Thisoption may be given more than once. Note that using this optioninappropriately may make the output file unusable.
-S
--strip-all
Do not copy relocation and symbol information from the source file.
-g
--strip-debug
Do not copy debugging symbols 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 wouldnormally 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 optionmay be given more than once.
--strip-unneeded-symbol=symbolname
Do not copy symbol symbolname from the source file unless it is neededby 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 localto the file, so that they are not visible externally. This option maybe given more than once.
--localize-hidden
In an ELF object, mark all symbols that have hidden or internal visibilityas local. This option applies on top of symbol-specific localization optionssuch as -L.
-L symbolname
--localize-symbol=symbolname
Make symbol symbolname local to the file, so that it is notvisible externally. This option may be given more than once.
-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 visibleoutside of the file in which it is defined. This option may be givenmore than once.
-w
--wildcard
Permit regular expressions in symbolnames used in other commandline options. The question mark (?), asterisk (*), backslash (\) andsquare brackets ([]) operators can be used anywhere in the symbolname. If the first character of the symbol name is the exclamationpoint (!) 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 optionthen start the range of bytes to keep at the byteth byte.byte can be in the range from 0 to breadth-1, wherebreadth is the value given by the --interleave option.
-i [breadth]
--interleave[=breadth]
Only copy a range out of every breadth bytes. (Header data isnot affected). Select which byte in the range begins the copy withthe --byte option. Select the width of the range with the--interleave-width option.

This option is useful for creating files to program ROM. It istypically used with an "srec" output target. Note thatobjcopy 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 bytesfrom the input to the output.

--interleave-width=width
When used with the --interleave option, copy widthbytes at a time. The start of the range of bytes to be copied is setby the --byte option, and the extent of the range is set withthe --interleave option.

The default value for this option is 1. The value of width plusthe byte value set by the --byte option must not exceedthe interleave breadth set by the --interleave option.

This option can be used to create images for two 16-bit flashes interleavedin a 32-bit bus by passing -b 0 -i 4 --interleave-width=2and -b 2 -i 4 --interleave-width=2 to two objcopycommands. 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 sameas those of the input file.
--debugging
Convert debugging information, if possible. This is not the defaultbecause only certain debugging formats are supported, and theconversion process can be time consuming.
--gap-fill val
Fill gaps between sections with val. This operation applies tothe load address (LMA) of the sections. It is done by increasingthe size of the section with the lower address, and filling in the extraspace created with val.
--pad-to address
Pad the output file up to the load address address. This isdone by increasing the size of the last section. The extra space isfilled 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 fileformats support setting the start address.
--change-start incr
--adjust-start incr
Change the start address by adding incr. Not all object fileformats support setting the start address.
--change-addresses incr
--adjust-vma incr
Change the VMA and LMA addresses of all sections, as well as the startaddress, by adding incr. Some object file formats do not permitsection addresses to be changed arbitrarily. Note that this does notrelocate the sections; if the program expects sections to be loaded at acertain address, and this option is used to change the sections suchthat they are loaded at a different address, the program may fail.
--change-section-address section{=,+,-}val
--adjust-section-vma section{=,+,-}val
Set or change both the VMA address and the LMA address of the namedsection. If = is used, the section address is set toval. Otherwise, val is added to or subtracted from thesection address. See the comments under --change-addresses,above. If section does not exist in the input file, a warning willbe issued, unless --no-change-warnings is used.
--change-section-lma section{=,+,-}val
Set or change the LMA address of the named section. The LMAaddress is the address where the section will be loaded into memory atprogram load time. Normally this is the same as the VMA address, whichis 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 bedifferent. If = is used, the section address is set toval. Otherwise, val is added to or subtracted from thesection address. See the comments under --change-addresses,above. If section does not exist in the input file, a warningwill be issued, unless --no-change-warnings is used.
--change-section-vma section{=,+,-}val
Set or change the VMA address of the named section. The VMAaddress is the address where the section will be located once theprogram has started executing. Normally this is the same as the LMAaddress, which is the address where the section will be loaded intomemory, but on some systems, especially those where a program is held inROM, the two can be different. If = is used, the section addressis set to val. Otherwise, val is added to or subtractedfrom the section address. See the comments under--change-addresses, above. If section does not exist inthe input file, a warning will be issued, unless--no-change-warnings is used.
--change-warnings
--adjust-warnings
If --change-section-address or --change-section-lma or--change-section-vma is used, and the named section does notexist, 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, evenif the named section does not exist.
--set-section-flags section=flags
Set the flags for the named section. The flags argument is acomma separated string of flag names. The recognized names arealloc, contents, load, noload,readonly, code, data, rom, share, anddebug. You can set the contents flag for a section whichdoes not have contents, but it is not meaningful to clear thecontents flag of a section which does have contents---just removethe section instead. Not all flags are meaningful for all object fileformats.
--add-section sectionname=filename
Add a new section named sectionname while copying the file. Thecontents of the new section are taken from the file filename. Thesize of the section will be the size of the file. This option onlyworks on file formats which can support sections with arbitrary names.
--rename-section oldname=newname[,flags]
Rename a section from oldname to newname, optionallychanging the section's flags to flags in the process. This hasthe advantage over usng a linker script to perform the rename in thatthe output stays as an object file and does not become a linkedexecutable.

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 binarydata 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 disablethe use of long section names in the output object; when disableis in effect, any long section names in the input object will be truncated.The enable option will only emit long section names if any arepresent in the inputs; this is mostly the same as keep, but itis 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 ofsymbols. The most common such character is underscore, which compilersoften add before every symbol. This option tells objcopy tochange the leading character of every symbol when it converts betweenobject file formats. If the object file formats use the same leadingcharacter, this option has no effect. Otherwise, it will add acharacter, or remove a character, or change a character, asappropriate.
--remove-leading-char
If the first character of a global symbol is a special symbol leadingcharacter used by the object file format, remove the character. Themost common symbol leading character is underscore. This option willremove a leading underscore from all global symbols. This can be usefulif you want to link together objects of different file formats withdifferent conventions for symbol names. This is different from--change-leading-char because it always changes the symbol namewhen appropriate, regardless of the object file format of the outputfile.
--reverse-bytes=num
Reverse the bytes in a section with output contents. A section length mustbe evenly divisible by the value given in order for the swap to be able totake place. Reversing takes place before the interleaving is performed.

This option is used typically in generating ROM images for problematictarget systems. For example, on some target boards, the 32-bit wordsfetched from 8-bit ROMs are re-assembled in little-endian byte orderregardless of the CPU byte order. Depending on the programming model, theendianness of the ROM may need to be modified.

Consider a simple file with a section containing the following eightbytes: 12345678.

Using --reverse-bytes=2 for the above example, the bytes in theoutput file would be ordered 21436587.

Using --reverse-bytes=4 for the above example, the bytes in theoutput 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 secondoutput file would be ordered 34127856.

--srec-len=ival
Meaningful only for srec output. Set the maximum length of the Srecordsbeing produced to ival. This length covers both address, data andcrc 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 usefulwhen one is trying link two things together for which you have nosource, 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 hashcharacter. This option may be given more than once.
--weaken
Change all global symbols in the file to be weak. This can be usefulwhen building an object which will be linked against other objects usingthe -R option to the linker. This option is only effective whenusing an object file format which supports weak symbols.
--keep-symbols=filename
Apply --keep-symbol option to each symbol listed in the filefilename. filename is simply a flat file, with one symbolname 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 filefilename. filename is simply a flat file, with one symbolname 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 inthe file filename. filename is simply a flat file, with onesymbol name per line. Line comments may be introduced by the hashcharacter. This option may be given more than once.
--keep-global-symbols=filename
Apply --keep-global-symbol option to each symbol listed in thefile filename. filename is simply a flat file, with onesymbol name per line. Line comments may be introduced by the hashcharacter. This option may be given more than once.
--localize-symbols=filename
Apply --localize-symbol option to each symbol listed in the filefilename. filename is simply a flat file, with one symbolname 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 filefilename. filename is simply a flat file, with one symbolname 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 filefilename. filename is simply a flat file, with one symbolname 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 theindexth code instead of the default one. This is useful in casea machine is assigned an official code and the tool-chain adopts thenew code, but other applications still depend on the original codebeing used. For ELF based architectures if the indexalternative does not exist then the value is treated as an absolutenumber 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 allobject file formats.
--readonly-text
Make the output text write protected. This option isn't meaningful for allobject file formats.
--pure
Mark the output file as demand paged. This option isn't meaningful for allobject file formats.
--impure
Mark the output file as impure. This option isn't meaningful for allobject 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 withstring.
--add-gnu-debuglink=path-to-file
Creates a .gnu_debuglink section which contains a reference to path-to-fileand adds it to the output file.
--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 bestripped by --strip-debug and leaving the debugging sectionsintact. In ELF files, this preserves all note sections in the output.

The intention is that this option will be used in conjunction with--add-gnu-debuglink to create a two part executable. One astripped binary which will occupy less space in RAM and in adistribution and the second a debugging information file which is onlyneeded if debugging abilities are required. The suggested procedureto create these files is as follows:

1.<Link the executable as normal. Assuming that is 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 infofile is arbitrary. Also the "--only-keep-debug" step isoptional. 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 thefull 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. Itdoes not make sense to use it on object files where the debugginginformation may be incomplete. Besides the gnu_debuglink featurecurrently only supports the presence of one filename containingdebugging information, not multiple filenames on a one-per-object-filebasis.

--file-alignment num
Specify the file alignment. Sections in the file will always begin atfile offsets which are multiples of this number. This defaults to512.[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 isthe lowest memory location that will be used when your program or dllis loaded. To reduce the need to relocate and improve performance ofyour dlls, each should have a unique base address and not overlap anyother dlls. The default is 0x400000 for executables, and 0x10000000for dlls.[This option is specific to PE targets.]
--section-alignment num
Sets the section alignment. Sections in memory will always begin ataddresses 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. Thelegal values for which are "native", "windows","console", "posix", "efi-app", "efi-bsd","efi-rtd", "sal-rtd", and "xbox". You may optionally setthe subsystem version also. Numeric values are also accepted forwhich.[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-symbolslinker input file.

--compress-debug-sections
Compress DWARF debug sections using zlib.
--decompress-debug-sections
Decompress DWARF debug sections using zlib.
-V
--version
Show the version number of objcopy.
-v
--verbose
Verbose output: list all object files modified. In the case ofarchives, 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 areinserted in place of the original @file option. If filedoes not exist, or cannot be read, then the option will be treatedliterally, and not removed.

Options in file are separated by whitespace. A whitespacecharacter may be included in an option by surrounding the entireoption in either single or double quotes. Any character (including abackslash) may be included by prefixing the character to be includedwith a backslash. The file may itself contain additional@file options; any such options will be processed recursively.

 

SEE ALSO

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

COPYRIGHT

Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.3or any later version published by the Free Software Foundation;with no Invariant Sections, with no Front-Cover Texts, and with noBack-Cover Texts. A copy of the license is included in thesection entitled ``GNU Free Documentation License''.


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO
COPYRIGHT

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