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OBJCOPY

Section: GNU Development Tools (1)
Updated: 2002-08-05
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]
        [-G symbolname|--keep-global-symbol=symbolname]
        [-L symbolname|--localize-symbol=symbolname]
        [-W symbolname|--weaken-symbol=symbolname]
        [-x|--discard-all] [-X|--discard-locals]
        [-b byte|--byte=byte]
        [-i interleave|--interleave=interleave]
        [-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]]
        [--change-leading-char ] [--remove-leading-char]
        [--srec-len=ival ] [--srec-forceS3]
        [--redefine-sym old=new ]
        [--weaken]
        [--keep-symbols=filename]
        [--strip-symbols=filename]
        [--keep-global-symbols=filename]
        [--localize-symbols=filename]
        [--weaken-symbols=filename]
        [--alt-machine-code=index]
        [-v|--verbose]
        [-V|--version]
        [--help]
        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 (eg srec).

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 raw binary 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 from the source file.

--strip-unneeded

Strip all symbols that are not needed for relocation processing.

-K symbolname

--keep-symbol=symbolname

Copy only symbol symbolname from the source file. This option maybe 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.

-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.

-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.

-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

Keep only every byteth byte of the input file (header data is notaffected). byte can be in the range from 0 to interleave-1,where interleave is given by the -i or --interleaveoption, or the default of 4. This option is useful for creating filesto program ROM. It is typically used with an "srec" outputtarget.

-i interleave

--interleave=interleave

Only copy one out of every interleave bytes. Select which byte tocopy with the -b or --byte option. The default is 4.objcopy ignores this option if you do not specify either -b or--byte.

-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>

--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.

--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.

--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.

--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.

--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 the new code, but other applications still depend on the original codebeing used.

-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.

COPYRIGHT

Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.1or 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''.

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