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OBJDUMP(1) |
GNU Development Tools |
OBJDUMP(1) |
objdump - display information from object files.
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]
[--dwarf-depth=n]
[--dwarf-start=n]
[--special-syms]
[--prefix=prefix]
[--prefix-strip=level]
[--insn-width=width]
[-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,-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.
This option also has a subtle effect on the disassembly of
instructions in code sections. When option -d is in effect
objdump will assume that any symbols present in a code section occur on
the boundary between instructions and it will refuse to disassemble
across such a boundary. When option -D is in effect however this
assumption is supressed. This means that it is possible for the output
of -d and -D to differ if, for example, data is stored in
code sections.
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.
Note, in some cases it is possible for a section to have both
the READONLY and the NOREAD attributes set. In such cases the NOREAD
attribute takes precedence, but objdump will report both since
the exact setting of the flag bits might be important.
- -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"
- "i8086"
- Select disassembly for the given architecture.
- "intel"
- "att"
- Select between intel syntax mode and AT&T syntax mode.
- "amd64"
- "intel64"
- Select between AMD64 ISA and Intel64 ISA.
- "intel-mnemonic"
- "att-mnemonic"
- Select between intel mnemonic mode and AT&T mnemonic mode. Note:
"intel-mnemonic" implies
"intel" and
"att-mnemonic" implies
"att".
- "addr64"
- "addr32"
- "addr16"
- "data32"
- "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.
- "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.
- "msa"
- Disassemble MSA instructions.
- "virt"
- Disassemble the virtualization ASE instructions.
- "xpa"
- Disassemble the eXtended Physical Address (XPA) ASE instructions.
- "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"
- "toc"
- "ldinfo"
Not all object formats support this option. In particular the ELF
format does not use it.
- -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]
- --dwarf[=aranges,=macro,=frames,=frames-interp,=str,=loc]
- --dwarf[=Ranges,=pubtypes,=trace_info,=trace_abbrev]
- --dwarf[=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.
nm(1), readelf(1), and the Info entries for binutils.
Copyright (c) 1991-2016 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 1.3
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".
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