avr-objdump (1) - Linux Man Pages
avr-objdump: display information from object files.
objdump - display information from object files.
DESCRIPTIONobjdump 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.
OPTIONSThe 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.
- 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.
- -b 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.
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.
- 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.
- 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.
- Like -g, but the information is generated in a format compatible with ctags tool.
- Display the assembler mnemonics for the machine instructions from objfile. This option only disassembles those sections which are expected to contain instructions.
Like -d, but disassemble the contents of all sections, not just
those expected to contain instructions.
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.
- When disassembling, print the complete address on each line. This is the older disassembly format.
- 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
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.
- Print a summary of the options to objdump and exit.
- Display a list showing all architectures and object formats available for specification with -b or -m.
- -j name
- 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.
- -m 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
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 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 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:
- 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.
- Disassemble the virtualization ASE instructions.
- 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.
- 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
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 and ldinfo.
- 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. As for -r, if used with -d or -D, the relocations are printed interspersed with the disassembly.
- 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.
- Specify prefix to add to the absolute paths when used with -S.
- Indicate how many initial directory names to strip off the hardwired absolute paths. It has no effect without --prefix=prefix.
- When disassembling instructions, print the instruction in hex as well as in 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 width bytes on a single line when disassembling instructions.
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.
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
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.
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.
- Enable additional checks for consistency of Dwarf information.
- 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 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:
- 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.
- The symbol is weak (w) or strong (a space).
- The symbol denotes a constructor (C) or an ordinary symbol (a space).
- 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.
- 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).
- The symbol is a debugging symbol (d) or a dynamic symbol (D) or a normal symbol (a space).
- The symbol is the name of a function (F) or a file (f) or an object (O) or just a normal symbol (a space).
- 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.
- 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.
- Print the version number of objdump and exit.
- 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.
- Normally the disassembly output will skip blocks of zeroes. This option directs the disassembler to disassemble those blocks, just like any other data.
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.
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