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OBJDUMP(1) GNU Development Tools OBJDUMP(1)

NAME

objdump - display information from object files.

SYNOPSIS

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]
[-P options|--private=options]
[-r|--reloc]
[-R|--dynamic-reloc]
[-s|--full-contents]
[-W[lLiaprmfFsoRt]|
--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index]]
[-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]
[--prefix=prefix]
[--prefix-strip=level]
[--insn-width=width]
[-V|--version]
[-H|--help]
objfile...

DESCRIPTION

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.

OPTIONS

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,-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.

-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.

-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.

If the target is an ARM architecture this switch also has the
effect of forcing the disassembler to decode pieces of data found
in code sections as if they were 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.

If the target is an ARM architecture then this switch has an
additional effect. It restricts the disassembly to only those
instructions supported by the architecture specified by machine.
If it is necessary to use this switch because the input file does
not contain any architecture information, but it is also desired to
disassemble all the instructions use -marm.

-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 PowerPC, booke controls the 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.

-P options
--private=options
Print information that is specific to the object file format. The
argument options is a comma separated list that depends on the
format (the lists of options is displayed with the help).

For XCOFF, the available options are: header, aout, sections, syms,
relocs, lineno, loader, except, typchk, traceback and toc.

-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. As for -r, if used with -d or -D, the relocations are
printed interspersed with the disassembly.

-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.

--prefix=prefix
Specify prefix to add to the absolute paths when used with -S.

--prefix-strip=level
Indicate how many initial directory names to strip off the
hardwired absolute paths. It has no effect without --prefix=prefix.

--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.

--insn-width=width
Display width bytes on a single line when disassembling
instructions.

-W[lLiaprmfFsoRt]
--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index]
Displays the contents of the debug sections in the file, if any are
present. If one of the optional letters or words follows the
switch then only data found in those specific sections will be
dumped.

Note that there is no single letter option to display the content
of trace sections or .gdb_index.

Note: the output from the =info option can also be affected by the
options --dwarf-depth, the --dwarf-start and the --dwarf-check.

--dwarf-depth=n
Limit the dump of the ".debug_info" section to n children. This is
only useful with --dwarf=info. The default is to print all DIEs;
the special value 0 for n will also have this effect.

With a non-zero value for n, DIEs at or deeper than n levels will
not be printed. The range for n is zero-based.

--dwarf-start=n
Print only DIEs beginning with the DIE numbered n. This is only
useful with --dwarf=info.

If specified, this option will suppress printing of any header
information and all DIEs before the DIE numbered n. Only siblings
and children of the specified DIE will be printed.

This can be used in conjunction with --dwarf-depth.

--dwarf-check
Enable additional checks for consistency of Dwarf information.

-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.

--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"
"u"
"!" The symbol is a local (l), global (g), unique global (u),
neither global nor local (a space) or both global and local
(!). 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. Unique global symbols are a GNU extension to the
standard set of ELF symbol bindings. For such a symbol the
dynamic linker will make sure that in the entire process there
is just one symbol with this name and type in use.

"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"
"i" The symbol is an indirect reference to another symbol (I), a
function to be evaluated during reloc processing (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.

@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.