RTEMS GNU Tools On-Line Library

objdump

GNU Binary Utilities

Chapter 4: objdump

objdump [ -a | --archive-headers ] 
        [ -b bfdname | --target=bfdname ] 
        [ -C | --demangle ]
        [ -d | --disassemble ]
        [ -D | --disassemble-all ]
        [ -z | --disassemble-zeroes ]
        [ -EB | -EL | --endian={big | little } ]
        [ -f | --file-headers ]
        [ --file-start-context ]
        [ -g | --debugging ]
        [ -h | --section-headers | --headers ]
        [ -i | --info ]
        [ -j section | --section=section ]
        [ -l | --line-numbers ]
        [ -S | --source ]
        [ -m machine | --architecture=machine ]
        [ -M options | --disassembler-options=options]
        [ -p | --private-headers ]
        [ -r | --reloc ]
        [ -R | --dynamic-reloc ]
        [ -s | --full-contents ]
        [ -G | --stabs ]
        [ -t | --syms ]
        [ -T | --dynamic-syms ]
        [ -x | --all-headers ]
        [ -w | --wide ]
        [ --start-address=address ]
        [ --stop-address=address ]
        [ --prefix-addresses]
        [ --[no-]show-raw-insn ]
        [ --adjust-vma=offset ]
        [ -V | --version ]
        [ -H | --help ]
        objfile...

objdump displays information about one or more object files. The options control what particular information to display. This information is mostly useful to programmers who are working on the compilation tools, as opposed to programmers who just want their program to compile and work.

objfile... are the object files to be examined. When you specify archives, objdump shows information on each of the member object files.

The long and short forms of options, shown here as alternatives, are equivalent. At least one option from the list `-a,-d,-D,-f,-g,-G,-h,-H,-p,-r,-R,-S,-t,-T,-V,-x' must be given.

-a

--archive-header

If any of the objfile files are archives, display the archive header information (in a format similar to `ls -l'). Besides the information you could list with `ar tv', `objdump -a' shows the object file format of each archive member.

--adjust-vma=offset

When dumping information, first add offset to all the section addresses. This is useful if the section addresses do not correspond to the symbol table, which can happen when putting sections at particular addresses when using a format which can not represent section addresses, such as a.out.

-b bfdname

--target=bfdname

Specify that the object-code format for the object files is bfdname. This option may not be necessary; objdump can automatically recognize many formats.

For example,

objdump -b oasys -m vax -h fu.o

displays summary information from the section headers (`-h') of `fu.o', which is explicitly identified (`-m') as a VAX object file in the format produced by Oasys compilers. You can list the formats available with the `-i' option. See Target Selection, for more information.

-C

--demangle

Decode (demangle) low-level symbol names into user-level names. Besides removing any initial underscore prepended by the system, this makes C++ function names readable. See c++filt, for more information on demangling.

-G

--debugging

Display debugging information. This attempts to parse debugging information stored in the file and print it out using a C like syntax. Only certain types of debugging information have been implemented.

-d

--disassemble

Display the assembler mnemonics for the machine instructions from objfile. This option only disassembles those sections which are expected to contain instructions.

-D

--disassemble-all

Like `-d', but disassemble the contents of all sections, not just those expected to contain instructions.

--prefix-addresses

When disassembling, print the complete address on each line. This is the older disassembly format.

--disassemble-zeroes

Normally the disassembly output will skip blocks of zeroes. This option directs the disassembler to disassemble those blocks, just like any other data.

-EB

-EL

--endian={big|little}

Specify the endianness of the object files. This only affects disassembly. This can be useful when disassembling a file format which does not describe endianness information, such as S-records.

-f

--file-header

Display summary information from the overall header of each of the objfile files.

--file-start-context

Specify that when displaying interlisted source code/disassembly (assumes '-S') from a file that has not yet been displayed, extend the context to the start of the file.

-h

--section-header

--header

Display summary information from the section headers of the object file.

File segments may be relocated to nonstandard addresses, for example by using the `-Ttext', `-Tdata', or `-Tbss' options to ld. However, some object file formats, such as a.out, do not store the starting address of the file segments. In those situations, although ld relocates the sections correctly, using `objdump -h' to list the file section headers cannot show the correct addresses. Instead, it shows the usual addresses, which are implicit for the target.

--help

Print a summary of the options to objdump and exit.

-i

--info

Display a list showing all architectures and object formats available for specification with `-b' or `-m'.

-j name

--section=name

Display information only for section name.

-l

--line-numbers

Label the display (using debugging information) with the filename and source line numbers corresponding to the object code or relocs shown. Only useful with `-d', `-D', or `-r'.

-m machine

--architecture=machine

Specify the architecture to use when disassembling object files. This can be useful when disassembling object files which do not describe architecture information, such as S-records. You can list the available architectures with the `-i' option.

-M options

--disassembler-options=options

Pass target specific information to the disassembler. Only supported on some targets.

If the target is an ARM architecture then this switch can be used to select which register name set is used during disassembler. Specifying `-M reg-name-std' (the default) will select the register names as used in ARM's instruction set documentation, but with register 13 called 'sp', register 14 called 'lr' and register 15 called 'pc'. Specifying `-M reg-names-apcs' will select the name set used by the ARM Procedure Call Standard, whilst specifying `-M reg-names-raw' will just use `r' followed by the register number.

There are also two variants on the APCS register naming scheme enabled by `-M reg-names-atpcs' and `-M reg-names-special-atpcs' which use the ARM/Thumb Procedure Call Standard naming conventions. (Eiuther with the normal register name sor the special register names).

This option can also be used for ARM architectures to force the disassembler to interpret all instructions as THUMB instructions by using the switch `--disassembler-options=force-thumb'. This can be useful when attempting to disassemble thumb code produced by other compilers.

-p

--private-headers

Print information that is specific to the object file format. The exact information printed depends upon the object file format. For some object file formats, no additional information is printed.

-r

--reloc

Print the relocation entries of the file. If used with `-d' or `-D', the relocations are printed interspersed with the disassembly.

-R

--dynamic-reloc

Print the dynamic relocation entries of the file. This is only meaningful for dynamic objects, such as certain types of shared libraries.

-s

--full-contents

Display the full contents of any sections requested.

-S

--source

Display source code intermixed with disassembly, if possible. Implies `-d'.

--show-raw-insn

When disassembling instructions, print the instruction in hex as well as in symbolic form. This is the default except when --prefix-addresses is used.

--no-show-raw-insn

When disassembling instructions, do not print the instruction bytes. This is the default when --prefix-addresses is used.

-G

--stabs

Display the full contents of any sections requested. Display the contents of the .stab and .stab.index and .stab.excl sections from an ELF file. This is only useful on systems (such as Solaris 2.0) in which .stab debugging symbol-table entries are carried in an ELF section. In most other file formats, debugging symbol-table entries are interleaved with linkage symbols, and are visible in the `--syms' output. For more information on stabs symbols, see Stabs.

--start-address=address

Start displaying data at the specified address. This affects the output of the -d, -r and -s options.

--stop-address=address

Stop displaying data at the specified address. This affects the output of the -d, -r and -s options.

-t

--syms

Print the symbol table entries of the file. This is similar to the information provided by the `nm' program.

-T

--dynamic-syms

Print the dynamic symbol table entries of the file. This is only meaningful for dynamic objects, such as certain types of shared libraries. This is similar to the information provided by the `nm' program when given the `-D' (`--dynamic') option.

--version

Print the version number of objdump and exit.

-x

--all-header

Display all available header information, including the symbol table and relocation entries. Using `-x' is equivalent to specifying all of `-a -f -h -r -t'.

-w

--wide

Format some lines for output devices that have more than 80 columns.

GNU Binary Utilities