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## 4 objdump

         objdump [-a|--archive-headers]
                 [-b bfdname|--target=bfdname]
                 [-C|--demangle[=style] ]
                 [-d|--disassemble]
                 [-D|--disassemble-all]
                 [-z|--disassemble-zeroes]
                 [-EB|-EL|--endian={big | little }]
                 [-f|--file-headers]
                 [-F|--file-offsets]
                 [--file-start-context]
                 [-g|--debugging]
                 [-e|--debugging-tags]
                 [-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]
                 [-W|--dwarf]
                 [-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]
                 [--special-syms]
                 [-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,-e,-f,-g,-G,-h,-H,-p,-r,-R,-s,-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[=style]
  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. Different compilers have different mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler. See c++filt, for more information on demangling.
-g
--debugging
  Display debugging information. This attempts to parse STABS and IEEE debugging format information stored in the file and print it out using a C like syntax. If neither of these formats are found this option falls back on the -W option to print any DWARF information in the file.
-e
--debugging-tags
  Like -g, but the information is generated in a format compatible with ctags tool.
-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.
-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-headers
  Display summary information from the overall header of each of the objfile files.
-F
--file-offsets
  When disassembling sections, whenever a symbol is displayed, also display the file offset of the region of data that is about to be dumped. If zeroes are being skipped, then when disassembly resumes, tell the user how many zeroes were skipped and the file offset of the location from where the disassembly resumes. When dumping sections, display the file offset of the location from where the dump starts.
--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-headers
--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 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.

-H
--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 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 -M reg-names-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. (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. x86-64, i386 and i8086 select disassembly for the given architecture. intel and att select between intel syntax mode and AT&T syntax mode. intel-mnemonic and att-mnemonic select between intel mnemonic mode and AT&T mnemonic mode. intel-mnemonic implies intel and att-mnemonic implies att. addr64, addr32, addr16, data32 and data16 specify the default address size and operand size. These four options will be overridden if 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. ppcps selects disassembly for the paired single instructions of the PPC750CL.

  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', '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 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 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 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 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.

-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. By default all non-empty sections are displayed.
-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.
-W
--dwarf
  Displays the contents of the DWARF debug sections in the file, if any are present.
-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 (The “stabs” debug format).
--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, although the display format is different. The format of the output depends upon the format of the file being dumped, but there are two main types. One looks like this:

                [  4](sec  3)(fl 0x00)(ty   0)(scl   3) (nx 1) 0x00000000 .bss
                [  6](sec  1)(fl 0x00)(ty   0)(scl   2) (nx 0) 0x00000000 fred

  where the number inside the square brackets is the number of the entry in the symbol table, the sec number is the section number, the fl value are the symbol's flag bits, the ty number is the symbol's type, the scl number is the symbol's storage class and the nx value is the number of auxilary entries associated with the symbol. The last two fields are the symbol's value and its name.

  The other common output format, usually seen with ELF based files, looks like this:

                00000000 l    d  .bss   00000000 .bss
                00000000 g       .text  00000000 fred

  Here the first number is the symbol's value (sometimes refered to as its address). The next field is actually a set of characters and spaces indicating the flag bits that are set on the symbol. These characters are described below. Next is the section with which the symbol is associated or *ABS* if the section is absolute (ie not connected with any section), or *UND* if the section is referenced in the file being dumped, but not defined there.

  After the section name comes another field, a number, which for common symbols is the alignment and for other symbol is the size. Finally the symbol's name is displayed.

  The flag characters are divided into 7 groups as follows:

  `l`
  `g`
  `!`
    The symbol is local (l), global (g), neither (a space) or both (!). A symbol can be neither local or global for a variety of reasons, e.g., because it is used for debugging, but it is probably an indication of a bug if it is ever both local and global.
  `w`
    The symbol is weak (w) or strong (a space).
  `C`
    The symbol denotes a constructor (C) or an ordinary symbol (a space).
  `W`
    The symbol is a warning (W) or a normal symbol (a space). A warning symbol's name is a message to be displayed if the symbol following the warning symbol is ever referenced.
  `I`
    The symbol is an indirect reference to another symbol (I) or a normal symbol (a space).
  `d`
  `D`
    The symbol is a debugging symbol (d) or a dynamic symbol (D) or a normal symbol (a space).
  `F`
  `f`
  `O`
    The symbol is the name of a function (F) or a file (f) or an object (O) or just a normal symbol (a space).
-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.
--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.
-V
--version
  Print the version number of objdump and exit.
-x
--all-headers
  Display all available header information, including the symbol table and relocation entries. Using -x is equivalent to specifying all of -a -f -h -p -r -t.
-w
--wide
  Format some lines for output devices that have more than 80 columns. Also do not truncate symbol names when they are displayed.
-z
--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.