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Manual Pages  — OBJDUMP


objdump - display information from object files.



objdump [-a|--archive-headers]
[-b bfdname|--target=bfdname]
[-C|--demangle[=style] ]
[-EB|-EL|--endian={big | little }]
[-j section|--section=section]
[-m machine|--architecture=machine]
[-M options|--disassembler-options=options]


amp;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.

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

GNU amp;objdump will be removed from a future version of the FreeBSD base system. Users who require GNU amp;objdump are advised to install the binutils port or package.


The long and short forms of options, shown here as alternatives, are equivalent. At least one option from the list amp;-a,-d,-D,-e,-f,-g,-G,-h,-H,-p,-r,-R,-s,-S,-t,-T,-V,-x must be given.
--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 amp;bfdname. This option may not be necessary; objdump can automatically recognize many formats.

For example,

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

displays summary information from the section headers (-h) of amp;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.

--demangle[=style] Decode (demangle) low-level symbol names into user-level names. Besides removing any initial underscore prepended by the system, this makes C mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler.
--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. Some other types are supported by readelf -w.
--debugging-tags Like -g, but the information is generated in a format compatible with ctags tool.
--disassemble Display the assembler mnemonics for the machine instructions from amp;objfile. This option only disassembles those sections which are expected to contain instructions.
--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.
--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.
--file-headers 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.
--headers 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 amp;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 amp;-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.
--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.
--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 it is necessary to specify more than one disassembler option then multiple -M options can be used or can be placed together into a comma separated list.

If the target is an ARM architecture then this switch can be used to select which register name set is used during disassembler. Specifying amp;-M reg-names-std (the default) will select the register names as used in ARM's instruction set documentation, but with register 13 called amp;'sp', register 14 called 'lr' and register 15 called 'pc'. Specifying amp;-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. (Either with the normal register names or 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.

For the x86, some of the options duplicate functions of the -m switch, but allow finer grained control. Multiple selections from the following may be specified as a comma separated string. amp;x86-64, i386 and i8086 select disassembly for the given architecture. intel and att select between intel syntax mode and AT&T syntax mode. addr64, addr32, amp;addr16, data32 and data16 specify the default address size and operand size. These four options will be overridden if amp;x86-64, i386 or i8086 appear later in the option string. Lastly, suffix, when in AT&T mode, instructs the disassembler to print a mnemonic suffix even when the suffix could be inferred by the operands.

For PPC, booke, booke32 and booke64 select disassembly of BookE instructions. 32 and 64 select PowerPC and PowerPC64 disassembly, respectively. e300 selects disassembly for the e300 family. 440 selects disassembly for the PowerPC 440.

For MIPS, this option controls the printing of instruction mnemonic names and register names in disassembled instructions. Multiple selections from the following may be specified as a comma separated string, and invalid options are ignored:
no-aliases Print the 'raw' instruction mnemonic instead of some pseudo instruction mnemonic. I.e., print 'daddu' or 'or' instead of 'move', amp;'sll' instead of 'nop', etc.
gpr-names=ABI Print GPR (general-purpose register) names as appropriate for the specified ABI. By default, GPR names are selected according to the ABI of the binary being disassembled.
fpr-names=ABI Print FPR (floating-point register) names as appropriate for the specified ABI. By default, FPR numbers are printed rather than names.
cp0-names=ARCH Print CP0 (system control coprocessor; coprocessor 0) register names as appropriate for the CPU or architecture specified by amp;ARCH. By default, CP0 register names are selected according to the architecture and CPU of the binary being disassembled.
hwr-names=ARCH Print HWR (hardware register, used by the rdhwr instruction) names as appropriate for the CPU or architecture specified by amp;ARCH. By default, HWR names are selected according to the architecture and CPU of the binary being disassembled.
reg-names=ABI Print GPR and FPR names as appropriate for the selected ABI.
reg-names=ARCH Print CPU-specific register names (CP0 register and HWR names) as appropriate for the selected CPU or architecture.

For any of the options listed above, ABI or amp;ARCH may be specified as numeric to have numbers printed rather than names, for the selected types of registers. You can list the available values of ABI and ARCH using the --help option.

For VAX, you can specify function entry addresses with -M entry:0xf00ba. You can use this multiple times to properly disassemble VAX binary files that don't contain symbol tables (like amp;ROM dumps). In these cases, the function entry mask would otherwise be decoded as VAX instructions, which would probably lead the rest of the function being wrongly disassembled.

--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.
--reloc Print the relocation entries of the file. If used with -d or amp;-D, the relocations are printed interspersed with the disassembly.
--dynamic-reloc Print the dynamic relocation entries of the file. This is only meaningful for dynamic objects, such as certain types of shared libraries.
--full-contents Display the full contents of any sections requested. By default all non-empty sections are displayed.
--source Display source code intermixed with disassembly, if possible. Implies amp;-d.
--show-raw-insn When disassembling instructions, print the instruction in hex as well as in symbolic form. This is the default except when amp;--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.
--dwarf Displays the contents of the DWARF debug sections in the file, if any are present.
--stabs Display the full contents of any sections requested. Display the contents of the .stab and .stab.index and .stab.excl sections from an amp;ELF file. This is only useful on systems (such as Solaris 2.0) in which amp;.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.
--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.
--syms Print the symbol table entries of the file. This is similar to the information provided by the nm program.
--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.
--special-syms When displaying symbols include those which the target considers to be special in some way and which would not normally be of interest to the user.
--version Print the version number of objdump and exit.
--all-headers Display all available header information, including the symbol table and relocation entries. Using -x is equivalent to specifying all of amp;-a -f -h -p -r -t.
--wide Format some lines for output devices that have more than 80 columns. Also do not truncate symbol names when they are displayed.
--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.
@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.


amp;nm(1), readelf(1), and the Info entries for binutils.


Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 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 1.1 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''.

2010-10-30 OBJDUMP (1) binutils-2.17.50

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