MAN page from RedHat 8.X binutils-


Section: GNU Development Tools (1)
Updated: 2002-08-05


objdump - display information from object files. 


objdump [-a|--archive-headers]
        [-b bfdname|--target=bfdname]
        [-C|--demangle[=style] ]
        [-EB|-EL|--endian={big | little }]
        [-j section|--section=section]
        [-m machine|--architecture=machine]
        [-M options|--disassembler-options=options]


objdump displays information about one or more object files.The options control what particular information to display. Thisinformation is mostly useful to programmers who are working on thecompilation tools, as opposed to programmers who just want theirprogram to compile and work.

objfile... are the object files to be examined. When youspecify archives, objdump shows information on each of the memberobject files. 


The long and short forms of options, shown here as alternatives, areequivalent. At least one option from the list-a,-d,-D,-f,-g,-G,-h,-H,-p,-r,-R,-S,-t,-T,-V,-x must be given.
If any of the objfile files are archives, display the archiveheader information (in a format similar to ls -l). Besides theinformation you could list with ar tv, objdump -a showsthe object file format of each archive member.
When dumping information, first add offset to all the sectionaddresses. This is useful if the section addresses do not correspond tothe symbol table, which can happen when putting sections at particularaddresses when using a format which can not represent section addresses,such as a.out.
-b bfdname
Specify that the object-code format for the object files isbfdname. This option may not be necessary; objdump canautomatically recognize many formats.

For example,

        objdump -b oasys -m vax -h fu.o
displays summary information from the section headers (-h) offu.o, which is explicitly identified (-m) as a VAX objectfile in the format produced by Oasys compilers. You can list theformats available with the -i option.
Decode (demangle) low-level symbol names into user-level names.Besides removing any initial underscore prepended by the system, thismakes C++ function names readable. Different compilers have differentmangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler.
Display debugging information. This attempts to parse debugginginformation stored in the file and print it out using a C like syntax.Only certain types of debugging information have been implemented.
Display the assembler mnemonics for the machine instructions fromobjfile. This option only disassembles those sections which areexpected to contain instructions.
Like -d, but disassemble the contents of all sections, not justthose expected to contain instructions.
When disassembling, print the complete address on each line. This isthe older disassembly format.
Normally the disassembly output will skip blocks of zeroes. Thisoption directs the disassembler to disassemble those blocks, just likeany other data.
Specify the endianness of the object files. This only affectsdisassembly. This can be useful when disassembling a file format whichdoes not describe endianness information, such as S-records.
Display summary information from the overall header ofeach of the objfile files.
Specify that when displaying interlisted source code/disassembly(assumes -S) from a file that has not yet been displayed, extend thecontext to the start of the file.
Display summary information from the section headers of theobject file.

File segments may be relocated to nonstandard addresses, for example byusing the -Ttext, -Tdata, or -Tbss options told. However, some object file formats, such as a.out, do notstore 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 thetarget.

Print a summary of the options to objdump and exit.
Display a list showing all architectures and object formats availablefor specification with -b or -m.
-j name
Display information only for section name.
Label the display (using debugging information) with the filename andsource line numbers corresponding to the object code or relocs shown.Only useful with -d, -D, or -r.
-m machine
Specify the architecture to use when disassembling object files. Thiscan be useful when disassembling object files which do not describearchitecture information, such as S-records. You can list the availablearchitectures with the -i option.
-M options
Pass target specific information to the disassembler. Only supported onsome targets.

If the target is an ARM architecture then this switch can be used toselect which register name set is used during disassembler. Specifying-M reg-name-std (the default) will select the register names asused 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 ARMProcedure Call Standard, whilst specifying -M reg-names-raw willjust use r followed by the register number.

There are also two variants on the APCS register naming scheme enabledby -M reg-names-atpcs and -M reg-names-special-atpcs whichuse the ARM/Thumb Procedure Call Standard naming conventions. (Eitherwith the normal register name or the special register names).

This option can also be used for ARM architectures to force thedisassembler to interpret all instructions as Thumb instructions byusing the switch --disassembler-options=force-thumb. This can beuseful when attempting to disassemble thumb code produced by othercompilers.

For the x86, some of the options duplicate functions of the -mswitch, but allow finer grained control. Multiple selections from thefollowing may be specified as a comma separated string.x86-64, i386 and i8086 select disassembly forthe given architecture. intel and att select betweenintel syntax mode and AT&T syntax mode. addr32,addr16, data32 and data16 specify the defaultaddress size and operand size. These four options will be overridden ifx86-64, i386 or i8086 appear later in theoption string. Lastly, suffix, when in AT&T mode,instructs the dissassembler to print a mnemonic suffix even when thesuffix could be inferred by the operands.

For PPC, booke, booke32 and booke64 selectdisassembly of BookE instructions. 32 and 64 selectPowerPC and PowerPC64 disassembly, respectively.

Print information that is specific to the object file format. The exactinformation printed depends upon the object file format. For someobject file formats, no additional information is printed.
Print the relocation entries of the file. If used with -d or-D, the relocations are printed interspersed with thedisassembly.
Print the dynamic relocation entries of the file. This is onlymeaningful for dynamic objects, such as certain types of sharedlibraries.
Display the full contents of any sections requested.
Display source code intermixed with disassembly, if possible. Implies-d.
When disassembling instructions, print the instruction in hex as well asin symbolic form. This is the default except when--prefix-addresses is used.
When disassembling instructions, do not print the instruction bytes.This is the default when --prefix-addresses is used.
Display the full contents of any sections requested. Display thecontents of the .stab and .stab.index and .stab.excl sections from anELF file. This is only useful on systems (such as Solaris 2.0) in which".stab" debugging symbol-table entries are carried in an ELFsection. In most other file formats, debugging symbol-table entries areinterleaved with linkage symbols, and are visible in the --symsoutput.
Start displaying data at the specified address. This affects the outputof the -d, -r and -s options.
Stop displaying data at the specified address. This affects the outputof 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.
Print the dynamic symbol table entries of the file. This is onlymeaningful for dynamic objects, such as certain types of sharedlibraries. This is similar to the information provided by the nmprogram when given the -D (--dynamic) option.
Print the version number of objdump and exit.
Display all available header information, including the symbol table andrelocation entries. Using -x is equivalent to specifying all of-a -f -h -r -t.
Format some lines for output devices that have more than 80 columns.Also do not truncate symbol names when they are displayed.


nm(1), readelf(1), and the Info entries for binutils. 


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Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.1or any later version published by the Free Software Foundation;with no Invariant Sections, with no Front-Cover Texts, and with noBack-Cover Texts. A copy of the license is included in thesection entitled ``GNU Free Documentation License''.




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