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]
[
--dwarf-depth=n]
[
--dwarf-start=n]
[
--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.
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.
SEE ALSO
nm(1),
readelf(1), and the Info entries for
binutils.
COPYRIGHT
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".