OBJDUMP(1)

📦
version 2.40.50~ti1ubuntu1 · 2 versions
, in ubuntu noble

✨ OBJDUMP(1) ✨

GNU Development Tools · the one and only objdump 💅

okay bestie, sit down, grab a boba 🧋, because we are about to read object files together and it's gonna be iconic.

🌸 NAME 🌸

objdump — display information from object files

so like. it shows you stuff inside object files. that's the whole vibe. 🦋

🎀 SYNOPSIS 🎀

objdump [-a|--archive-headers]
        [-b bfdname|--target=bfdname]
        [-C|--demangle[=style] ]
        [-d|--disassemble[=symbol]]
        [-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]
        [--source-comment[=text]]
        [-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[lLiaprmfFsoORtUuTgAck]|
         --dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links]]
        [-WK|--dwarf=follow-links]
        [-WN|--dwarf=no-follow-links]
        [-wD|--dwarf=use-debuginfod]
        [-wE|--dwarf=do-not-use-debuginfod]
        [-L|--process-links]
        [--ctf=section]
        [--sframe=section]
        [-G|--stabs]
        [-t|--syms]
        [-T|--dynamic-syms]
        [-x|--all-headers]
        [-w|--wide]
        [--start-address=address]
        [--stop-address=address]
        [--no-addresses]
        [--prefix-addresses]
        [--[no-]show-raw-insn]
        [--adjust-vma=offset]
        [--show-all-symbols]
        [--dwarf-depth=n]
        [--dwarf-start=n]
        [--ctf-parent=section]
        [--no-recurse-limit|--recurse-limit]
        [--special-syms]
        [--prefix=prefix]
        [--prefix-strip=level]
        [--insn-width=width]
        [--visualize-jumps[=color|=extended-color|=off]
        [--disassembler-color=[off|terminal|on|extended]
        [-U method] [--unicode=method]
        [-V|--version]
        [-H|--help]
        objfile...

look at her. so many little flags. she's giving ✨versatile✨ and honestly? we stan.

💖 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.

ngl that last sentence is a read but it's true — this is compiler-people territory, not "my code won't build" territory. 😭

objfile... are the object files to be examined. When you specify archives, objdump shows information on each of the member object files.

so like, you can yeet a whole archive at her and she'll go through every single member like the icon she is. 👑

🌈 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.

🚨 bestie listen: you cannot just run objdump with nothing. she needs at least ONE of those. it's giving "no thoughts, no output".
  • -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. so it's ar tv but with extra lore. 🎁
  • --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. sliding everything over so the numbers actually line up.
  • -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. turning _ZN3foo3barEv back into something a human can love. 💖
  • --recurse-limit, --no-recurse-limit, --recursion-limit, --no-recursion-limit — Enables or disables a limit on the amount of recursion performed whilst demangling strings. Since the name mangling formats allow for an infinite level of recursion it is possible to create strings whose decoding will exhaust the amount of stack space available on the host machine, triggering a memory fault. The limit tries to prevent this from happening by restricting recursion to 2048 levels of nesting.

The default is for this limit to be enabled, but disabling it may be necessary in order to demangle truly complicated names. Note however that if the recursion limit is disabled then stack exhaustion is possible and any bug reports about such an event will be rejected.

💀 do NOT turn this off unless you truly must. if you crash your own stack, that's on you, and the bug report is going in the bin. periodt.
  • -g, --debugging — Display debugging information. This attempts to parse STABS debugging format information stored in the file and print it out using a C like syntax. If no STABS debugging was 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. same energy, different packaging.
  • -d, --disassemble, --disassemble=symbol — Display the assembler mnemonics for the machine instructions from the input file. This option only disassembles those sections which are expected to contain instructions. If the optional symbol argument is given, then display the assembler mnemonics starting at symbol. If symbol is a function name then disassembly will stop at the end of the function, otherwise it will stop when the next symbol is encountered. If there are no matches for symbol then nothing will be displayed.

Note if the --dwarf=follow-links option is enabled then any symbol tables in linked debug info files will be read in and used when disassembling.

the classic. the moment. the girlies love a good disassembly. 🫶

  • -D, --disassemble-all — Like -d, but disassemble the contents of all non-empty non-bss sections, not just those expected to contain instructions. -j may be used to select specific sections.

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 suppressed. 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.

Note if the --dwarf=follow-links option is enabled then any symbol tables in linked debug info files will be read in and used when disassembling.

⚠️ yeah -d and -D can genuinely give you different output. that's not a bug, that's the assumption getting switched off.
  • --no-addresses — When disassembling, don't print addresses on each line or for symbols and relocation offsets. In combination with --no-show-raw-insn this may be useful for comparing compiler output. clean, minimalist, no clutter. 🎀
  • --prefix-addresses — When disassembling, print the complete address on each line. This is the older disassembly format. the vintage look. retro. she's always been that girl.
  • -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. receipts. she shows you exactly where she is in the file at all times. 🧾
  • --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. give me the WHOLE beginning, not just a teaser.
  • -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.

🌸 so if you see both READONLY and NOREAD chilling together, NOREAD wins, but she'll still show you both because the raw bits matter. iykyk.
  • -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. the directory of everything she can read. very useful, very underrated. 📚
  • -j name, --section=name — Display information for section name. This option may be specified multiple times. 🔂 stack them up, bestie, pick as many sections as your heart desires.
  • -L, --process-links — Display the contents of non-debug sections found in separate debuginfo files that are linked to the main file. This option automatically implies the -WK option, and only sections requested by other command line options will be displayed. 🔗
  • -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. 📍
💌 lowkey this is the perfect place to pause — but we are SO not done, there's a whole rest of the alphabet coming. 🦋
  • -m machine, --architecture=machine — okay so this is the "hey bestie, guess the architecture for me" switch 💅 it sets the architecture objdump uses when it disassembles object files. Super handy when your object files don't actually describe their architecture info (looking at you, S-records 👀). Wanna know which architectures you can pick from? Run -i and the whole menu shows up.

For most architectures you can hand over an architecture name AND a machine name, separated by a colon. So like foo:bar would mean the bar machine type inside the foo architecture. This is the move when objdump was configured to support multiple architectures.

If your target is an ARM architecture, this switch does a little extra: it restricts the disassembly to only those instructions that the architecture you specified supports. And if you're being forced to use this switch because your input file has zero architecture info, but you still want ALL the instructions disassembled — use -marm. ✨

  • -M options, --disassembler-options=options — pass target-specific info straight to the disassembler. Only some targets support this, no cap. Need more than one disassembler option? Stack multiple -M options, or squish them into one comma-separated list. 🎀

For ARC: dsp controls the printing of DSP instructions, spfp selects printing of FPX single precision FP instructions, dpfp selects printing of FPX double precision FP instructions, quarkse_em selects printing of special QuarkSE-EM instructions, fpuda selects printing of double precision assist instructions, fpus selects printing of FPU single precision FP instructions, and fpud selects printing of FPU double precision FP instructions. Also you can get all the immediates printed in hexadecimal with hex. By default? Short immediates print in decimal representation, and long immediate values print as hexadecimal. 🦋

cpu=... lets you enforce a particular ISA when disassembling instructions, overriding the -m value or whatever's sitting in the ELF file. This is useful for picking ARC EM or HS ISA, because the architecture is literally the same for those and the disassembler has to rely on private ELF header data to decide if the code is EM or HS. You can specify this option multiple times — but only the latest value gets used, bestie. Valid values are the same as for the assembler's -mcpu=... option.

If your target is an ARM architecture, this switch picks which register name set the disassembler uses. -M reg-names-std (that's the default) selects the register names as used in ARM's instruction set documentation, except register 13 is called sp, register 14 is called lr, and register 15 is called pc. -M reg-names-apcs selects the name set used by the ARM Procedure Call Standard, while -M reg-names-raw just uses 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 also works for ARM architectures to force the disassembler to interpret all instructions as Thumb instructions, by using --disassembler-options=force-thumb. Lowkey iconic when you're trying to disassemble thumb code that some other compiler produced.

For AArch64 targets, this switch sets whether instructions get disassembled as the most general instruction using the -M no-aliases option, or whether instruction notes get generated as comments in the disassembly using -M notes.

For x86, some of these options duplicate what -m does, but they give you finer grained control. 🔥

  • "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 five options get overridden if "x86-64", "i386" or "i8086" show up later in the option string.
  • "suffix" — when in AT&T mode, and also for a limited set of instructions when in Intel mode, tells the disassembler to print a mnemonic suffix even when the suffix could be inferred from the operands or, for certain instructions, the execution mode's defaults.

For PowerPC, the -M argument raw selects disassembly of hardware insns rather than aliases. So you'll see "rlwinm" instead of "clrlwi", and "addi" instead of "li". All of the -m arguments for gas that select a CPU are supported, and they are: 403, 405, 440, 464, 476, 601, 603, 604, 620, 7400, 7410, 7450, 7455, 750cl, 821, 850, 860, a2, booke, booke32, cell, com, e200z2, e200z4, e300, e500, e500mc, e500mc64, e500x2, e5500, e6500, efs, power4, power5, power6, power7, power8, power9, power10, ppc, ppc32, ppc64, ppc64bridge, ppcps, pwr, pwr2, pwr4, pwr5, pwr5x, pwr6, pwr7, pwr8, pwr9, pwr10, pwrx, titan, vle, and future. 😮‍💨

32 and 64 modify the default or a prior CPU selection, disabling and enabling 64-bit insns respectively. Also, altivec, any, lsp, htm, vsx, spe and spe2 add capabilities to a previous or later CPU selection. And any will disassemble any opcode known to binutils — BUT in cases where an opcode has two different meanings or different arguments, you may not see the disassembly you expect 🙈. And if you disassemble without giving a CPU selection, a default gets chosen from info gleaned by BFD from the object file headers, but the result again may not be as you expect.

For MIPS, this option controls the printing of instruction mnemonic names and register names in disassembled instructions. You can specify multiple selections from the following as a comma-separated string, and invalid options are just 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's specific to the object file format. The exact info printed depends on the object file format. For some object file formats, literally no additional information is printed. It's giving mystery 🎁
  • -P options, --private=options — print information specific to the object file format. The argument options is a comma separated list that depends on the format (the list 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"

For PE, the available options are:

  • "header"
  • "sections"

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 you use it with -d or -D, the relocations get printed interspersed with the disassembly. Mixing it up, we love to see it ✨
  • -R, --dynamic-reloc — print the dynamic relocation entries of the file. This is only meaningful for dynamic objects, like certain types of shared libraries. Same as with -r: if you use it with -d or -D, the relocations are printed interspersed with the disassembly. 🌈
  • -s, --full-contents — display the full contents of sections, often used in combination with -j to request specific sections. By default, all non-empty non-bss sections are displayed. She's thorough 💅
  • -S, --source — display source code intermixed with disassembly, if possible. Implies -d. Main character energy, showing the receipts 🫶
  • --show-all-symbols — when you're disassembling, this one shows all the symbols that match a given address, not just the first one it bumps into. no more "wait, where did that other symbol go" 💅
  • --source-comment[=txt] — literally the -S option but every source code line gets a prefix of txt slapped in front of it. usually txt is a comment string so you can tell the assembler code apart from the source code, iconic behaviour honestly. if txt isn't given, the default string is "# " (hash then a space). 🎀
  • --prefix=prefix — specify prefix to add to the absolute paths when you're using -S.
  • --prefix-strip=level — tells it how many initial directory names to strip off the hardwired absolute paths. heads up bestie, it does nothing without --prefix=prefix.
  • --show-raw-insn — when disassembling instructions, print the instruction in hex and in symbolic form. this is the default, except when --prefix-addresses is in play.
  • --no-show-raw-insn — when disassembling instructions, don't 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.
  • --visualize-jumps[=color|=extended-color|=off] — visualize jumps that stay inside a function by drawing ASCII art between the start and target addresses 🦋. the optional =color argument adds color to the output using simple terminal colors. alternatively =extended-color adds color using 8bit colors — but those might not work on all terminals, so vibe check your setup first.

if you ever need to disable the visualize-jumps option after it's already been enabled, use visualize-jumps=off. simple as.

  • --disassembler-color=off
  • --disassembler-color=terminal
  • --disassembler-color=on|color|colour
  • --disassembler-color=extened|extended-color|extened-colour

— enables or disables colored syntax highlighting in disassembly output ✨. the default behaviour is decided via a configure time option. note that not all architectures support colored syntax highlighting, and depending on the terminal you're using, colored output may not actually be legible. so like… pretty but maybe unreadable, pick your fighter.

  • the on argument adds colors using simple terminal colors.
  • the terminal argument does the same thing, but only if the output device is a terminal.
  • the extended-color argument is similar to on, but it uses 8-bit colors. these may not work on all terminals.
  • the off argument disables colored disassembly.
  • -W[lLiaprmfFsoORtUuTgAckK]
  • --dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links,=follow-links]

— displays the contents of the DWARF debug sections in the file, if any are present 🙈. compressed debug sections get automatically decompressed (temporarily!) before they're displayed. if one or more of the optional letters or words follows the switch, then only those type(s) of data get dumped. the letters and words refer to the following info:

  • "a" / "=abbrev" — displays the contents of the .debug_abbrev section.
  • "A" / "=addr" — displays the contents of the .debug_addr section.
  • "c" / "=cu_index" — displays the contents of the .debug_cu_index and/or .debug_tu_index sections.
  • "f" / "=frames" — display the raw contents of a .debug_frame section.
  • "F" / "=frames-interp" — display the interpreted contents of a .debug_frame section.
  • "g" / "=gdb_index" — displays the contents of the .gdb_index and/or .debug_names sections.
  • "i" / "=info" — displays the contents of the .debug_info section. note: the output from this option can also be restricted by using the --dwarf-depth and --dwarf-start options.
  • "k" / "=links" — displays the contents of the .gnu_debuglink, .gnu_debugaltlink and .debug_sup sections, if any of them are present. also displays any links to separate dwarf object files (dwo), if they're specified by the DW_AT_GNU_dwo_name or DW_AT_dwo_name attributes in the .debug_info section.
  • "K" / "=follow-links" — display the contents of any selected debug sections that are found in linked, separate debug info file(s). this can result in multiple versions of the same debug section being displayed if it exists in more than one file.

in addition, when displaying DWARF attributes, if a form is found that references the separate debug info file, then the referenced contents will also be displayed.

note — in some distributions this option is enabled by default. it can be disabled via the N debug option. the default can be chosen when configuring the binutils via the --enable-follow-debug-links=yes or --enable-follow-debug-links=no options. if these aren't used, then the default is to enable the following of debug links.
note — if support for the debuginfod protocol was enabled when the binutils were built, then this option will also include an attempt to contact any debuginfod servers mentioned in the DEBUGINFOD_URLS environment variable. this could take some time to resolve 😭. this behaviour can be disabled via the =do-not-use-debuginfod debug option.
  • "N" / "=no-follow-links" — disables the following of links to separate debug info files.
  • "D" / "=use-debuginfod" — enables contacting debuginfod servers if there's a need to follow debug links. this is the default behaviour.
  • "E" / "=do-not-use-debuginfod" — disables contacting debuginfod servers when there's a need to follow debug links.
  • "l" / "=rawline" — displays the contents of the .debug_line section in a raw format.
  • "L" / "=decodedline" — displays the interpreted contents of the .debug_line section.
  • "m" / "=macro" — displays the contents of the .debug_macro and/or .debug_macinfo sections.
  • "o" / "=loc" — displays the contents of the .debug_loc and/or .debug_loclists sections.
  • "O" / "=str-offsets" — displays the contents of the .debug_str_offsets section.
  • "p" / "=pubnames" — displays the contents of the .debug_pubnames and/or .debug_gnu_pubnames sections.
  • "r" / "=aranges" — displays the contents of the .debug_aranges section.
  • "R" / "=Ranges" — displays the contents of the .debug_ranges and/or .debug_rnglists sections.
  • "s" / "=str" — displays the contents of the .debug_str, .debug_line_str and/or .debug_str_offsets sections.
  • "t" / "=pubtype" — displays the contents of the .debug_pubtypes and/or .debug_gnu_pubtypes sections.
  • "T" / "=trace_aranges" — displays the contents of the .trace_aranges section.
  • "u" / "=trace_abbrev" — displays the contents of the .trace_abbrev section.
  • "U" / "=trace_info" — displays the contents of the .trace_info section.
note: displaying the contents of .debug_static_funcs, .debug_static_vars and debug_weaknames sections is not currently supported. tragic, i know 💀
  • --dwarf-depth=n — limit the dump of the ".debug_info" section to n children. this is only useful with --debug-dump=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 --debug-dump=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.
  • --ctf[=section] — display the contents of the specified CTF section. CTF sections themselves contain many subsections, all of which are displayed in order.

by default, display the name of the section named .ctf, which is the name emitted by ld.

  • --ctf-parent=member — if the CTF section contains ambiguously-defined types, it will consist of an archive of many CTF dictionaries, all inheriting from one dictionary containing unambiguous types. this member is by default named .ctf, like the section containing it, but it's possible to change this name using the "ctf_link_set_memb_name_changer" function at link time. when looking at CTF archives that have been created by a linker that uses the name changer to rename the parent archive member, --ctf-parent can be used to specify the name used for the parent. 👑
  • --sframe[=section] — display the contents of the specified SFrame section.

by default, display the name of the section named .sframe, which is the name emitted by ld.

  • -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. iykyk 🌈

  • --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 info provided by the nm program, although the display format is different. the format of the output depends on 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 auxiliary entries associated with the symbol. The last two fields are the symbol's value and its name. periodt. 💅

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 referred 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. ✨

The output format is similar to that produced by the --syms option, except that an extra field is inserted before the symbol's name, giving the version information associated with the symbol. If the version is the default version to be used when resolving unversioned references to the symbol then it's displayed as is, otherwise it's put into parentheses.

  • --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.
  • -U [d|i|l|e|x|h], --unicode=[default|invalid|locale|escape|hex|highlight] — Controls the display of UTF-8 encoded multibyte characters in strings. The default (--unicode=default) is to give them no special treatment. The --unicode=locale option displays the sequence in the current locale, which may or may not support them. The options --unicode=hex and --unicode=invalid display them as hex byte sequences enclosed by either angle brackets or curly braces. 🌈

The --unicode=escape option displays them as escape sequences (\uxxxx) and the --unicode=highlight option displays them as escape sequences highlighted in red (if supported by the output device). The colouring is intended to draw attention to the presence of unicode sequences where they might not be expected.

  • -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. iconic.
  • -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. bestie behavior fr fr. 🫶

Copyright (c) 1991-2023 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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