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.
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.
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.
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.
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.
Display the assembler mnemonics for the machine instructions from
objfile. This option only disassembles those sections which are
expected to contain instructions.
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.
Display summary information from the overall header of
each of the objfile files.
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.
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.
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.
Display a list showing all architectures and object formats available
for specification with -b or -m.
Display information only for section name.
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.
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 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
gpr-names=
ABI
fpr-names=
ABI
cp0-names=
ARCH
hwr-names=
ARCH
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
reg-names=
ARCH
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.
Print the relocation entries of the file. If used with -d or
-D, the relocations are printed interspersed with the
disassembly.
Print the dynamic relocation entries of the file. This is only
meaningful for dynamic objects, such as certain types of shared
libraries.
Display the full contents of any sections requested. By default all
non-empty sections are displayed.
Display source code intermixed with disassembly, if possible. Implies
-d.
Displays the contents of the DWARF debug sections in the file, if any
are present.
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 displaying data at the specified address. This affects the output
of the -d, -r and -s options.
Stop displaying data at the specified address. This affects the output
of the -d, -r and -s options.
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
!
w
C
W
I
d
D
F
f
O
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.
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.
Format some lines for output devices that have more than 80 columns.
Also do not truncate symbol names when they are displayed.
Corrections, suggestions, and new documentation should be posted to the Forum.
The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.