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<h2 class="chapter">4 objdump</h2>
<p><a name="index-object-file-information-57"></a><a name="index-objdump-58"></a>
<!-- man title objdump display information from object files. -->
<pre class="smallexample"> <!-- man begin SYNOPSIS objdump -->
objdump [<span class="option">-a</span>|<span class="option">--archive-headers</span>]
[<span class="option">-b</span> <var>bfdname</var>|<span class="option">--target=</span><var>bfdname</var>]
[<span class="option">-C</span>|<span class="option">--demangle</span>[=<var>style</var>] ]
[<span class="option">-d</span>|<span class="option">--disassemble</span>]
[<span class="option">-D</span>|<span class="option">--disassemble-all</span>]
[<span class="option">-z</span>|<span class="option">--disassemble-zeroes</span>]
[<span class="option">-EB</span>|<span class="option">-EL</span>|<span class="option">--endian=</span>{big | little }]
[<span class="option">-f</span>|<span class="option">--file-headers</span>]
[<span class="option">-F</span>|<span class="option">--file-offsets</span>]
[<span class="option">--file-start-context</span>]
[<span class="option">-g</span>|<span class="option">--debugging</span>]
[<span class="option">-e</span>|<span class="option">--debugging-tags</span>]
[<span class="option">-h</span>|<span class="option">--section-headers</span>|<span class="option">--headers</span>]
[<span class="option">-i</span>|<span class="option">--info</span>]
[<span class="option">-j</span> <var>section</var>|<span class="option">--section=</span><var>section</var>]
[<span class="option">-l</span>|<span class="option">--line-numbers</span>]
[<span class="option">-S</span>|<span class="option">--source</span>]
[<span class="option">-m</span> <var>machine</var>|<span class="option">--architecture=</span><var>machine</var>]
[<span class="option">-M</span> <var>options</var>|<span class="option">--disassembler-options=</span><var>options</var>]
[<span class="option">-p</span>|<span class="option">--private-headers</span>]
[<span class="option">-r</span>|<span class="option">--reloc</span>]
[<span class="option">-R</span>|<span class="option">--dynamic-reloc</span>]
[<span class="option">-s</span>|<span class="option">--full-contents</span>]
[<span class="option">-W</span>|<span class="option">--dwarf</span>]
[<span class="option">-G</span>|<span class="option">--stabs</span>]
[<span class="option">-t</span>|<span class="option">--syms</span>]
[<span class="option">-T</span>|<span class="option">--dynamic-syms</span>]
[<span class="option">-x</span>|<span class="option">--all-headers</span>]
[<span class="option">-w</span>|<span class="option">--wide</span>]
[<span class="option">--start-address=</span><var>address</var>]
[<span class="option">--stop-address=</span><var>address</var>]
[<span class="option">--prefix-addresses</span>]
[<span class="option">--[no-]show-raw-insn</span>]
[<span class="option">--adjust-vma=</span><var>offset</var>]
[<span class="option">--special-syms</span>]
[<span class="option">-V</span>|<span class="option">--version</span>]
[<span class="option">-H</span>|<span class="option">--help</span>]
<var>objfile</var>...
<!-- man end -->
</pre>
<!-- man begin DESCRIPTION objdump -->
<p><span class="command">objdump</span> 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.
<p><var>objfile</var><small class="dots">...</small> are the object files to be examined. When you
specify archives, <span class="command">objdump</span> shows information on each of the member
object files.
<!-- man end -->
<!-- man begin OPTIONS objdump -->
<p>The long and short forms of options, shown here as alternatives, are
equivalent. At least one option from the list
<span class="option">-a,-d,-D,-e,-f,-g,-G,-h,-H,-p,-r,-R,-s,-S,-t,-T,-V,-x</span> must be given.
<dl>
<dt><span class="env">-a</span><dt><span class="env">--archive-header</span><dd><a name="index-archive-headers-59"></a>If any of the <var>objfile</var> files are archives, display the archive
header information (in a format similar to <span class="samp">ls -l</span>). Besides the
information you could list with <span class="samp">ar tv</span>, <span class="samp">objdump -a</span> shows
the object file format of each archive member.
<br><dt><span class="env">--adjust-vma=</span><var>offset</var><dd><a name="index-section-addresses-in-objdump-60"></a><a name="index-VMA-in-objdump-61"></a>When dumping information, first add <var>offset</var> 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.
<br><dt><span class="env">-b </span><var>bfdname</var><dt><span class="env">--target=</span><var>bfdname</var><dd><a name="index-object-code-format-62"></a>Specify that the object-code format for the object files is
<var>bfdname</var>. This option may not be necessary; <var>objdump</var> can
automatically recognize many formats.
<p>For example,
<pre class="example"> objdump -b oasys -m vax -h fu.o
</pre>
<p class="noindent">displays summary information from the section headers (<span class="option">-h</span>) of
<span class="file">fu.o</span>, which is explicitly identified (<span class="option">-m</span>) as a VAX object
file in the format produced by Oasys compilers. You can list the
formats available with the <span class="option">-i</span> option.
See <a href="Target-Selection.html#Target-Selection">Target Selection</a>, for more information.
<br><dt><span class="env">-C</span><dt><span class="env">--demangle[=</span><var>style</var><span class="env">]</span><dd><a name="index-demangling-in-objdump-63"></a>Decode (<dfn>demangle</dfn>) 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 <a href="c_002b_002bfilt.html#c_002b_002bfilt">c++filt</a>,
for more information on demangling.
<br><dt><span class="env">-g</span><dt><span class="env">--debugging</span><dd>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 <span class="option">-W</span> option to print any DWARF information in
the file.
<br><dt><span class="env">-e</span><dt><span class="env">--debugging-tags</span><dd>Like <span class="option">-g</span>, but the information is generated in a format compatible
with ctags tool.
<br><dt><span class="env">-d</span><dt><span class="env">--disassemble</span><dd><a name="index-disassembling-object-code-64"></a><a name="index-machine-instructions-65"></a>Display the assembler mnemonics for the machine instructions from
<var>objfile</var>. This option only disassembles those sections which are
expected to contain instructions.
<br><dt><span class="env">-D</span><dt><span class="env">--disassemble-all</span><dd>Like <span class="option">-d</span>, but disassemble the contents of all sections, not just
those expected to contain instructions.
<br><dt><span class="env">--prefix-addresses</span><dd>When disassembling, print the complete address on each line. This is
the older disassembly format.
<br><dt><span class="env">-EB</span><dt><span class="env">-EL</span><dt><span class="env">--endian={big|little}</span><dd><a name="index-endianness-66"></a><a name="index-disassembly-endianness-67"></a>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.
<br><dt><span class="env">-f</span><dt><span class="env">--file-headers</span><dd><a name="index-object-file-header-68"></a>Display summary information from the overall header of
each of the <var>objfile</var> files.
<br><dt><span class="env">-F</span><dt><span class="env">--file-offsets</span><dd><a name="index-object-file-offsets-69"></a>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.
<br><dt><span class="env">--file-start-context</span><dd><a name="index-source-code-context-70"></a>Specify that when displaying interlisted source code/disassembly
(assumes <span class="option">-S</span>) from a file that has not yet been displayed, extend the
context to the start of the file.
<br><dt><span class="env">-h</span><dt><span class="env">--section-headers</span><dt><span class="env">--headers</span><dd><a name="index-section-headers-71"></a>Display summary information from the section headers of the
object file.
<p>File segments may be relocated to nonstandard addresses, for example by
using the <span class="option">-Ttext</span>, <span class="option">-Tdata</span>, or <span class="option">-Tbss</span> options to
<span class="command">ld</span>. However, some object file formats, such as a.out, do not
store the starting address of the file segments. In those situations,
although <span class="command">ld</span> relocates the sections correctly, using <span class="samp">objdump
-h</span> to list the file section headers cannot show the correct addresses.
Instead, it shows the usual addresses, which are implicit for the
target.
<br><dt><span class="env">-H</span><dt><span class="env">--help</span><dd>Print a summary of the options to <span class="command">objdump</span> and exit.
<br><dt><span class="env">-i</span><dt><span class="env">--info</span><dd><a name="index-architectures-available-72"></a><a name="index-object-formats-available-73"></a>Display a list showing all architectures and object formats available
for specification with <span class="option">-b</span> or <span class="option">-m</span>.
<br><dt><span class="env">-j </span><var>name</var><dt><span class="env">--section=</span><var>name</var><dd><a name="index-section-information-74"></a>Display information only for section <var>name</var>.
<br><dt><span class="env">-l</span><dt><span class="env">--line-numbers</span><dd><a name="index-source-filenames-for-object-files-75"></a>Label the display (using debugging information) with the filename and
source line numbers corresponding to the object code or relocs shown.
Only useful with <span class="option">-d</span>, <span class="option">-D</span>, or <span class="option">-r</span>.
<br><dt><span class="env">-m </span><var>machine</var><dt><span class="env">--architecture=</span><var>machine</var><dd><a name="index-architecture-76"></a><a name="index-disassembly-architecture-77"></a>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 <span class="option">-i</span> option.
<br><dt><span class="env">-M </span><var>options</var><dt><span class="env">--disassembler-options=</span><var>options</var><dd>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 <span class="option">-M</span> options can be used or
can be placed together into a comma separated list.
<p>If the target is an ARM architecture then this switch can be used to
select which register name set is used during disassembler. Specifying
<span class="option">-M reg-names-std</span> (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
<span class="option">-M reg-names-apcs</span> will select the name set used by the ARM
Procedure Call Standard, whilst specifying <span class="option">-M reg-names-raw</span> will
just use <span class="samp">r</span> followed by the register number.
<p>There are also two variants on the APCS register naming scheme enabled
by <span class="option">-M reg-names-atpcs</span> and <span class="option">-M reg-names-special-atpcs</span> which
use the ARM/Thumb Procedure Call Standard naming conventions. (Either
with the normal register names or the special register names).
<p>This option can also be used for ARM architectures to force the
disassembler to interpret all instructions as Thumb instructions by
using the switch <span class="option">--disassembler-options=force-thumb</span>. This can be
useful when attempting to disassemble thumb code produced by other
compilers.
<p>For the x86, some of the options duplicate functions of the <span class="option">-m</span>
switch, but allow finer grained control. Multiple selections from the
following may be specified as a comma separated string.
<span class="option">x86-64</span>, <span class="option">i386</span> and <span class="option">i8086</span> select disassembly for
the given architecture. <span class="option">intel</span> and <span class="option">att</span> select between
intel syntax mode and AT&T syntax mode.
<span class="option">intel-mnemonic</span> and <span class="option">att-mnemonic</span> select between
intel mnemonic mode and AT&T mnemonic mode. <span class="option">intel-mnemonic</span>
implies <span class="option">intel</span> and <span class="option">att-mnemonic</span> implies <span class="option">att</span>.
<span class="option">addr64</span>, <span class="option">addr32</span>,
<span class="option">addr16</span>, <span class="option">data32</span> and <span class="option">data16</span> specify the default
address size and operand size. These four options will be overridden if
<span class="option">x86-64</span>, <span class="option">i386</span> or <span class="option">i8086</span> appear later in the
option string. Lastly, <span class="option">suffix</span>, when in AT&T mode,
instructs the disassembler to print a mnemonic suffix even when the
suffix could be inferred by the operands.
<p>For PPC, <span class="option">booke</span>, <span class="option">booke32</span> and <span class="option">booke64</span> select
disassembly of BookE instructions. <span class="option">32</span> and <span class="option">64</span> select
PowerPC and PowerPC64 disassembly, respectively. <span class="option">e300</span>
selects disassembly for the e300 family. <span class="option">440</span> selects
disassembly for the PowerPC 440. <span class="option">ppcps</span> selects disassembly
for the paired single instructions of the PPC750CL.
<p>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:
<dl>
<dt><code>no-aliases</code><dd>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.
<br><dt><code>gpr-names=</code><var>ABI</var><dd>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.
<br><dt><code>fpr-names=</code><var>ABI</var><dd>Print FPR (floating-point register) names as
appropriate for the specified ABI. By default, FPR numbers are printed
rather than names.
<br><dt><code>cp0-names=</code><var>ARCH</var><dd>Print CP0 (system control coprocessor; coprocessor 0) register names
as appropriate for the CPU or architecture specified by
<var>ARCH</var>. By default, CP0 register names are selected according to
the architecture and CPU of the binary being disassembled.
<br><dt><code>hwr-names=</code><var>ARCH</var><dd>Print HWR (hardware register, used by the <code>rdhwr</code> instruction) names
as appropriate for the CPU or architecture specified by
<var>ARCH</var>. By default, HWR names are selected according to
the architecture and CPU of the binary being disassembled.
<br><dt><code>reg-names=</code><var>ABI</var><dd>Print GPR and FPR names as appropriate for the selected ABI.
<br><dt><code>reg-names=</code><var>ARCH</var><dd>Print CPU-specific register names (CP0 register and HWR names)
as appropriate for the selected CPU or architecture.
</dl>
<p>For any of the options listed above, <var>ABI</var> or
<var>ARCH</var> may be specified as <span class="samp">numeric</span> to have numbers printed
rather than names, for the selected types of registers.
You can list the available values of <var>ABI</var> and <var>ARCH</var> using
the <span class="option">--help</span> option.
<p>For VAX, you can specify function entry addresses with <span class="option">-M
entry:0xf00ba</span>. 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.
<br><dt><span class="env">-p</span><dt><span class="env">--private-headers</span><dd>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.
<br><dt><span class="env">-r</span><dt><span class="env">--reloc</span><dd><a name="index-relocation-entries_002c-in-object-file-78"></a>Print the relocation entries of the file. If used with <span class="option">-d</span> or
<span class="option">-D</span>, the relocations are printed interspersed with the
disassembly.
<br><dt><span class="env">-R</span><dt><span class="env">--dynamic-reloc</span><dd><a name="index-dynamic-relocation-entries_002c-in-object-file-79"></a>Print the dynamic relocation entries of the file. This is only
meaningful for dynamic objects, such as certain types of shared
libraries.
<br><dt><span class="env">-s</span><dt><span class="env">--full-contents</span><dd><a name="index-sections_002c-full-contents-80"></a><a name="index-object-file-sections-81"></a>Display the full contents of any sections requested. By default all
non-empty sections are displayed.
<br><dt><span class="env">-S</span><dt><span class="env">--source</span><dd><a name="index-source-disassembly-82"></a><a name="index-disassembly_002c-with-source-83"></a>Display source code intermixed with disassembly, if possible. Implies
<span class="option">-d</span>.
<br><dt><span class="env">--show-raw-insn</span><dd>When disassembling instructions, print the instruction in hex as well as
in symbolic form. This is the default except when
<span class="option">--prefix-addresses</span> is used.
<br><dt><span class="env">--no-show-raw-insn</span><dd>When disassembling instructions, do not print the instruction bytes.
This is the default when <span class="option">--prefix-addresses</span> is used.
<br><dt><span class="env">-W</span><dt><span class="env">--dwarf</span><dd><a name="index-DWARF-84"></a><a name="index-debug-symbols-85"></a>Displays the contents of the DWARF debug sections in the file, if any
are present.
<br><dt><span class="env">-G</span><dt><span class="env">--stabs</span><dd><a name="index-stab-86"></a><a name="index-_002estab-87"></a><a name="index-debug-symbols-88"></a><a name="index-ELF-object-file-format-89"></a>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
<code>.stab</code> 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 <span class="option">--syms</span>
output.
For more information on stabs symbols, see <a href="../stabs/index.html#Top">Stabs (The “stabs” debug format)</a>.
<br><dt><span class="env">--start-address=</span><var>address</var><dd><a name="index-start_002daddress-90"></a>Start displaying data at the specified address. This affects the output
of the <span class="option">-d</span>, <span class="option">-r</span> and <span class="option">-s</span> options.
<br><dt><span class="env">--stop-address=</span><var>address</var><dd><a name="index-stop_002daddress-91"></a>Stop displaying data at the specified address. This affects the output
of the <span class="option">-d</span>, <span class="option">-r</span> and <span class="option">-s</span> options.
<br><dt><span class="env">-t</span><dt><span class="env">--syms</span><dd><a name="index-symbol-table-entries_002c-printing-92"></a>Print the symbol table entries of the file.
This is similar to the information provided by the <span class="samp">nm</span> 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:
<pre class="smallexample"> [ 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
</pre>
<p>where the number inside the square brackets is the number of the entry
in the symbol table, the <var>sec</var> number is the section number, the
<var>fl</var> value are the symbol's flag bits, the <var>ty</var> number is the
symbol's type, the <var>scl</var> number is the symbol's storage class and
the <var>nx</var> value is the number of auxilary entries associated with
the symbol. The last two fields are the symbol's value and its name.
<p>The other common output format, usually seen with ELF based files,
looks like this:
<pre class="smallexample"> 00000000 l d .bss 00000000 .bss
00000000 g .text 00000000 fred
</pre>
<p>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 <em>*ABS*</em> if the section is absolute (ie
not connected with any section), or <em>*UND*</em> if the section is
referenced in the file being dumped, but not defined there.
<p>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.
<p>The flag characters are divided into 7 groups as follows:
<dl>
<dt><code>l</code><dt><code>g</code><dt><code>!</code><dd>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.
<br><dt><code>w</code><dd>The symbol is weak (w) or strong (a space).
<br><dt><code>C</code><dd>The symbol denotes a constructor (C) or an ordinary symbol (a space).
<br><dt><code>W</code><dd>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.
<br><dt><code>I</code><dd>The symbol is an indirect reference to another symbol (I) or a normal
symbol (a space).
<br><dt><code>d</code><dt><code>D</code><dd>The symbol is a debugging symbol (d) or a dynamic symbol (D) or a
normal symbol (a space).
<br><dt><code>F</code><br><dt><code>f</code><br><dt><code>O</code><dd>The symbol is the name of a function (F) or a file (f) or an object
(O) or just a normal symbol (a space).
</dl>
<br><dt><span class="env">-T</span><dt><span class="env">--dynamic-syms</span><dd><a name="index-dynamic-symbol-table-entries_002c-printing-93"></a>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 <span class="samp">nm</span>
program when given the <span class="option">-D</span> (<span class="option">--dynamic</span>) option.
<br><dt><span class="env">--special-syms</span><dd>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.
<br><dt><span class="env">-V</span><dt><span class="env">--version</span><dd>Print the version number of <span class="command">objdump</span> and exit.
<br><dt><span class="env">-x</span><dt><span class="env">--all-headers</span><dd><a name="index-all-header-information_002c-object-file-94"></a><a name="index-header-information_002c-all-95"></a>Display all available header information, including the symbol table and
relocation entries. Using <span class="option">-x</span> is equivalent to specifying all of
<span class="option">-a -f -h -p -r -t</span>.
<br><dt><span class="env">-w</span><dt><span class="env">--wide</span><dd><a name="index-wide-output_002c-printing-96"></a>Format some lines for output devices that have more than 80 columns.
Also do not truncate symbol names when they are displayed.
<br><dt><span class="env">-z</span><dt><span class="env">--disassemble-zeroes</span><dd>Normally the disassembly output will skip blocks of zeroes. This
option directs the disassembler to disassemble those blocks, just like
any other data.
</dl>
<!-- man end -->
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