The gnu Binary Utilities(GNU Binutils)
Version 2.42
January 2024

Roland H. Pesch
Jeffrey M. Osier
Cygnus Support

Cygnus Support
Texinfo 2022-11-07.17

Copyright c 1991-2024 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 theFree 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”.

iTable of Contents
1

ar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1
1.2

Controlling ar on the Command Line . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Controlling ar with a Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2ld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3

nm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4objcopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5

objdump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

6ranlib. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

7

size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

8strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

9strip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

10c++filt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

11addr2line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

12windmc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

13windres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

14dlltool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

14.1

The format of the dlltool .def file . . . . . . . . . . . . . . . . . . . . . . . . . . 77

15

readelf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

16

elfedit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

ii

17

Common Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

18

Selecting the Target System . . . . . . . . . . . . . . . . . 91

18.1
18.2

Target Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Architecture Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

19

debuginfod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

20

Reporting Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

20.1
20.2

Have You Found a Bug? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
How to Report Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Appendix A

GNU Free Documentation License . . 97

Binutils Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

1

1 ar
ar [-]p[mod] [--plugin name] [--target bfdname] [--output dirname] [--record-libdeps libdeps] [relpos] [count] archive [member...]ar -M [ <mri-script ]The gnu ar program creates, modifies, and extracts from archives. An archive is a single
file holding a collection of other files in a structure that makes it possible to retrieve theoriginal individual files (called members of the archive).
The original files’ contents, mode (permissions), timestamp, owner, and group arepreserved in the archive, and can be restored on extraction.
gnu ar can maintain archives whose members have names of any length; however,depending on how ar is configured on your system, a limit on member-name length may be
imposed for compatibility with archive formats maintained with other tools. If it exists, thelimit is often 15 characters (typical of formats related to a.out) or 16 characters (typical offormats related to coff).
ar is considered a binary utility because archives of this sort are most often used aslibraries holding commonly needed subroutines. Since libraries often will depend on otherlibraries, ar can also record the dependencies of a library when the --record-libdeps
option is specified.
ar creates an index to the symbols defined in relocatable object modules in the archive
when you specify the modifier ‘s’. Once created, this index is updated in the archive
whenever ar makes a change to its contents (save for the ‘q’ update operation). An archivewith such an index speeds up linking to the library, and allows routines in the library to calleach other without regard to their placement in the archive.
You may use ‘nm -s’ or ‘nm --print-armap’ to list this index table. If an archive lacks
the table, another form of ar called ranlib can be used to add just the table.
gnu ar can optionally create a thin archive, which contains a symbol index and references
to the original copies of the member files of the archive. This is useful for building libraries
for use within a local build tree, where the relocatable objects are expected to remain
available, and copying the contents of each object would only waste time and space.
An archive can either be thin or it can be normal. It cannot be both at the same time.
Once an archive is created its format cannot be changed without first deleting it and thencreating a new archive in its place.
Thin archives are also flattened, so that adding one thin archive to another thin archive
does not nest it, as would happen with a normal archive. Instead the elements of the firstarchive are added individually to the second archive.
The paths to the elements of the archive are stored relative to the archive itself.
gnu ar is designed to be compatible with two different facilities. You can control its
activity using command-line options, like the different varieties of ar on Unix systems; or, if
you specify the single command-line option -M, you can control it with a script supplied via
standard input, like the MRI “librarian” program.

Chapter 1: ar

2

1.1 Controlling ar on the Command Linear [-X32_64] [-]p[mod] [--plugin name] [--target bfdname] [--output dirname] [--recordlibdeps libdeps] [--thin] [relpos] [count] archive [member...]When you use ar in the Unix style, ar insists on at least two arguments to execute: one
keyletter specifying the operation (optionally accompanied by other keyletters specifying
modifiers), and the archive name to act on.
Most operations can also accept further member arguments, specifying particular files tooperate on.
gnu ar allows you to mix the operation code p and modifier flags mod in any order,
within the first command-line argument.
If you wish, you may begin the first command-line argument with a dash.
The p keyletter specifies what operation to execute; it may be any of the following, but
you must specify only one of them:‘d’Delete modules from the archive. Specify the names of modules to be deleted as
member . . . ; the archive is untouched if you specify no files to delete.
If you specify the ‘v’ modifier, ar lists each module as it is deleted.

‘m’

Use this operation to move members in an archive.
The ordering of members in an archive can make a difference in how programs
are linked using the library, if a symbol is defined in more than one member.
If no modifiers are used with m, any members you name in the member arguments
are moved to the end of the archive; you can use the ‘a’, ‘b’, or ‘i’ modifiers tomove them to a specified place instead.

‘p’Print the specified members of the archive, to the standard output file. If the‘v’ modifier is specified, show the member name before copying its contents tostandard output.
If you specify no member arguments, all the files in the archive are printed.

‘q’

Quick append ; Historically, add the files member . . . to the end of archive,
without checking for replacement.
The modifiers ‘a’, ‘b’, and ‘i’ do not affect this operation; new members arealways placed at the end of the archive.
The modifier ‘v’ makes ar list each file as it is appended.
Since the point of this operation is speed, implementations of ar have the optionof not updating the archive’s symbol table if one exists. Too many different
systems however assume that symbol tables are always up-to-date, so gnu ar
will rebuild the table even with a quick append.
Note - gnu ar treats the command ‘qs’ as a synonym for ‘r’ - replacing alreadyexisting files in the archive and appending new ones at the end.

‘r’

Insert the files member . . . into archive (with replacement). This operationdiffers from ‘q’ in that any previously existing members are deleted if theirnames match those being added.

Chapter 1: ar

3

If one of the files named in member . . . does not exist, ar displays an error
message, and leaves undisturbed any existing members of the archive matchingthat name.
By default, new members are added at the end of the file; but you may use oneof the modifiers ‘a’, ‘b’, or ‘i’ to request placement relative to some existing
member.
The modifier ‘v’ used with this operation elicits a line of output for each file
inserted, along with one of the letters ‘a’ or ‘r’ to indicate whether the file wasappended (no old member deleted) or replaced.
‘s’

Add an index to the archive, or update it if it already exists. Note this commandis an exception to the rule that there can only be one command letter, as it ispossible to use it as either a command or a modifier. In either case it does thesame thing.

‘t’

Display a table listing the contents of archive, or those of the files listed inmember . . . that are present in the archive. Normally only the member nameis shown, but if the modifier ‘O’ is specified, then the corresponding offset ofthe member is also displayed. Finally, in order to see the modes (permissions),
timestamp, owner, group, and size the ‘v’ modifier should be included.
If you do not specify a member, all files in the archive are listed.
If there is more than one file with the same name (say, ‘fie’) in an archive (say‘b.a’), ‘ar t b.a fie’ lists only the first instance; to see them all, you must ask
for a complete listing—in our example, ‘ar t b.a’.

‘x’

Extract members (named member) from the archive. You can use the ‘v’ modifier
with this operation, to request that ar list each name as it extracts it.
If you do not specify a member, all files in the archive are extracted.
Files cannot be extracted from a thin archive, and there are restrictions on
extracting from archives created with P: The paths must not be absolute, may
not contain .., and any subdirectories in the paths must exist. If it is desired
to avoid these restrictions then used the --output option to specify an output
directory.

A number of modifiers (mod) may immediately follow the p keyletter, to specify variations
on an operation’s behavior:‘a’

Add new files after an existing member of the archive. If you use the modifier ‘a’,
the name of an existing archive member must be present as the relpos argument,
before the archive specification.

‘b’

Add new files before an existing member of the archive. If you use the modifier‘b’, the name of an existing archive member must be present as the relpos
argument, before the archive specification. (same as ‘i’).

‘c’

Create the archive. The specified archive is always created if it did not exist,
when you request an update. But a warning is issued unless you specify inadvance that you expect to create it, by using this modifier.

Chapter 1: ar

4‘D’

Operate in deterministic mode. When adding files and the archive index use
zero for UIDs, GIDs, timestamps, and use consistent file modes for all files.
When this option is used, if ar is used with identical options and identical input
files, multiple runs will create identical output files regardless of the input files’
owners, groups, file modes, or modification times.
If binutils was configured with --enable-deterministic-archives, thenthis mode is on by default. It can be disabled with the ‘U’ modifier, below.

‘f’

Truncate names in the archive. gnu ar will normally permit file names of any
length. This will cause it to create archives which are not compatible with thenative ar program on some systems. If this is a concern, the ‘f’ modifier may
be used to truncate file names when putting them in the archive.

‘i’Insert new files before an existing member of the archive. If you use the modifier‘i’, the name of an existing archive member must be present as the relpos
argument, before the archive specification. (same as ‘b’).

‘l’Specify dependencies of this library. The dependencies must immediately follow
this option character, must use the same syntax as the linker command line, andmust be specified within a single argument. I.e., if multiple items are needed,
they must be quoted to form a single command line argument. For example ‘L"-L/usr/local/lib -lmydep1 -lmydep2"’‘N’

Uses the count parameter. This is used if there are multiple entries in the archivewith the same name. Extract or delete instance count of the given name fromthe archive.

‘o’

Preserve the original dates of members when extracting them. If you do not
specify this modifier, files extracted from the archive are stamped with the timeof extraction.

‘O’

Display member offsets inside the archive. Use together with the ‘t’ option.

‘P’

Use the full path name when matching or storing names in the archive. Archives
created with full path names are not POSIX compliant, and thus may not workwith tools other than up to date gnu tools. Modifying such archives with gnu
ar without using P will remove the full path names unless the archive is a thinarchive. Note that P may be useful when adding files to a thin archive since r
without P ignores the path when choosing which element to replace. Thusar rcST archive.a subdir/file1 subdir/file2 file1

will result in the first subdir/file1 being replaced with file1 from the current
directory. Adding P will prevent this replacement.
‘s’Write an object-file index into the archive, or update an existing one, even if noother change is made to the archive. You may use this modifier flag either withany operation, or alone. Running ‘ar s’ on an archive is equivalent to running‘ranlib’ on it.

‘S’

Do not generate an archive symbol table. This can speed up building a large
library in several steps. The resulting archive can not be used with the linker.
In order to build a symbol table, you must omit the ‘S’ modifier on the last
execution of ‘ar’, or you must run ‘ranlib’ on the archive.

Chapter 1: ar

5‘T’

Deprecated alias for --thin. T is not recommended because in many ar implementations T has a different meaning, as specified by X/Open System Interface.

‘u’

Normally, ‘ar r’. . . inserts all files listed into the archive. If you would like toinsert only those of the files you list that are newer than existing members of thesame names, use this modifier. The ‘u’ modifier is allowed only for the operation‘r’ (replace). In particular, the combination ‘qu’ is not allowed, since checking
the timestamps would lose any speed advantage from the operation ‘q’.
Note - if an archive has been created in a deterministic manner, eg via the useof the D modifier, then replacement will always happen and the u modifier will
be ineffective.

‘U’

Do not operate in deterministic mode. This is the inverse of the ‘D’ modifier, above: added files and the archive index will get their actual UID, GID,
timestamp, and file mode values.
This is the default unless binutils was configured with --enabledeterministic-archives.

‘v’This modifier requests the verbose version of an operation. Many operations
display additional information, such as filenames processed, when the modifier‘v’ is appended.

‘V’

This modifier shows the version number of ar.

The ar program also supports some command-line options which are neither modifiers
nor actions, but which do change its behaviour in specific ways:‘--help’

Displays the list of command-line options supported by ar and then exits.

‘--version’
Displays the version information of ar and then exits.
‘-X32_64’

ar ignores an initial option spelled ‘-X32_64’, for compatibility with AIX. The
behaviour produced by this option is the default for gnu ar. ar does not support
any of the other ‘-X’ options; in particular, it does not support -X32 which isthe default for AIX ar.

‘--plugin name’
The optional command-line switch --plugin name causes ar to load the plugincalled name which adds support for more file formats, including object files withlink-time optimization information.
This option is only available if the toolchain has been built with plugin support
enabled.
If --plugin is not provided, but plugin support has been enabled then ar
iterates over the files in ${libdir}/bfd-plugins in alphabetic order and thefirst plugin that claims the object in question is used.
Please note that this plugin search directory is not the one used by ld’s -plugin
option. In order to make ar use the linker plugin it must be copied into the${libdir}/bfd-plugins directory. For GCC based compilations the linker
plugin is called liblto_plugin.so.0.0.0. For Clang based compilations it iscalled LLVMgold.so. The GCC plugin is always backwards compatible withearlier versions, so it is sufficient to just copy the newest one.

Chapter 1: ar

6‘--target target’
The optional command-line switch --target bfdname specifies that the archive
members are in an object code format different from your system’s default
format. See See Section 18.1 [Target Selection], page 91, for more information.
‘--output dirname’
The --output option can be used to specify a path to a directory into whicharchive members should be extracted. If this option is not specified then thecurrent directory will be used.
Note - although the presence of this option does imply a x extraction operationthat option must still be included on the command line.
‘--record-libdeps libdeps’
The --record-libdeps option is identical to the l modifier, just handled inlong form.
‘--thin’

Make the specified archive a thin archive. If it already exists and is a regulararchive, the existing members must be present in the same directory as archive.

1.2 Controlling ar with a Script
ar -M [ <script ]If you use the single command-line option ‘-M’ with ar, you can control its operation
with a rudimentary command language. This form of ar operates interactively if standard
input is coming directly from a terminal. During interactive use, ar prompts for input (theprompt is ‘AR >’), and continues executing even after errors. If you redirect standard input
to a script file, no prompts are issued, and ar abandons execution (with a nonzero exit code)on any error.
The ar command language is not designed to be equivalent to the command-line options;in fact, it provides somewhat less control over archives. The only purpose of the commandlanguage is to ease the transition to gnu ar for developers who already have scripts written
for the MRI “librarian” program.
The syntax for the ar command language is straightforward:• commands are recognized in upper or lower case; for example, LIST is the same as list.
In the following descriptions, commands are shown in upper case for clarity.
• a single command may appear on each line; it is the first word on the line.
• empty lines are allowed, and have no effect.
• comments are allowed; text after either of the characters ‘*’ or ‘;’ is ignored.
• Whenever you use a list of names as part of the argument to an ar command, you canseparate the individual names with either commas or blanks. Commas are shown in the
explanations below, for clarity.
• ‘+’ is used as a line continuation character; if ‘+’ appears at the end of a line, the text
on the following line is considered part of the current command.
Here are the commands you can use in ar scripts, or when using ar interactively. Threeof them have special significance:
OPEN or CREATE specify a current archive, which is a temporary file required for most of
the other commands.

Chapter 1: ar

7

SAVE commits the changes so far specified by the script. Prior to SAVE, commands affectonly the temporary copy of the current archive.
ADDLIB archive
ADDLIB archive (module, module, ... module)
Add all the contents of archive (or, if specified, each named module from archive)
to the current archive.
Requires prior use of OPEN or CREATE.
ADDMOD member, member, ... member
Add each named member as a module in the current archive.
Requires prior use of OPEN or CREATE.
CLEAR

Discard the contents of the current archive, canceling the effect of any operations
since the last SAVE. May be executed (with no effect) even if no current archiveis specified.

CREATE archive
Creates an archive, and makes it the current archive (required for many othercommands). The new archive is created with a temporary name; it is not actually
saved as archive until you use SAVE. You can overwrite existing archives; similarly,
the contents of any existing file named archive will not be destroyed until SAVE.
DELETE module, module, ... module
Delete each listed module from the current archive; equivalent to ‘ar -d archivemodule ... module’.
Requires prior use of OPEN or CREATE.
DIRECTORY archive (module, ... module)
DIRECTORY archive (module, ... module) outputfile
List each named module present in archive. The separate command VERBOSE
specifies the form of the output: when verbose output is off, output is like thatof ‘ar -t archive module...’. When verbose output is on, the listing is like‘ar -tv archive module...’.
Output normally goes to the standard output stream; however, if you specify
outputfile as a final argument, ar directs the output to that file.
END

Exit from ar, with a 0 exit code to indicate successful completion. This command
does not save the output file; if you have changed the current archive since thelast SAVE command, those changes are lost.

EXTRACT module, module, ... module
Extract each named module from the current archive, writing them into thecurrent directory as separate files. Equivalent to ‘ar -x archive module...’.
Requires prior use of OPEN or CREATE.
LIST

Display full contents of the current archive, in “verbose” style regardless of thestate of VERBOSE. The effect is like ‘ar tv archive’. (This single command is a
gnu ar enhancement, rather than present for MRI compatibility.)
Requires prior use of OPEN or CREATE.

Chapter 1: ar

8

OPEN archive
Opens an existing archive for use as the current archive (required for manyother commands). Any changes as the result of subsequent commands will not
actually affect archive until you next use SAVE.
REPLACE module, module, ... module
In the current archive, replace each existing module (named in the REPLACE
arguments) from files in the current working directory. To execute this command
without errors, both the file, and the module in the current archive, must exist.
Requires prior use of OPEN or CREATE.
VERBOSE

Toggle an internal flag governing the output from DIRECTORY. When the flag ison, DIRECTORY output matches output from ‘ar -tv ’. . . .

SAVECommit your changes to the current archive, and actually save it as a file with
the name specified in the last CREATE or OPEN command.
Requires prior use of OPEN or CREATE.

9

2 ld
The gnu linker ld is now described in a separate manual. See Section “Overview” in Using
LD: the gnu linker.

10

3 nm
nm [-A|-o|--print-file-name][-a|--debug-syms][-B|--format=bsd][-C|--demangle[=style]][-D|--dynamic][-fformat|--format=format][-g|--extern-only][-h|--help][--ifunc-chars=CHARS][-j|--format=just-symbols][-l|--line-numbers] [--inlines][-n|-v|--numeric-sort][-P|--portability][-p|--no-sort][-r|--reverse-sort][-S|--print-size][-s|--print-armap][-t radix|--radix=radix][-u|--undefined-only][-U|--defined-only][-V|--version][-W|--no-weak][-X 32_64][--no-demangle][--no-recurse-limit|--recurse-limit]][--plugin name][--size-sort][--special-syms][--synthetic][--target=bfdname][--unicode=method][--with-symbol-versions][--without-symbol-versions][objfile...]gnu nm lists the symbols from object files objfile . . . . If no object files are listed asarguments, nm assumes the file a.out.
For each symbol, nm shows:• The symbol value, in the radix selected by options (see below), or hexadecimal by
default.
• The symbol type. At least the following types are used; others are, as well, dependingon the object file format. If lowercase, the symbol is usually local; if uppercase, thesymbol is global (external). There are however a few lowercase symbols that are shownfor special global symbols (u, v and w).
ABb

The symbol’s value is absolute, and will not be changed by further linking.
The symbol is in the BSS data section. This section typically contains
zero-initialized or uninitialized data, although the exact behavior is systemdependent.

Chapter 3: nm

C
c

D
d
G
g

11

The symbol is common. Common symbols are uninitialized data. Whenlinking, multiple common symbols may appear with the same name. If thesymbol is defined anywhere, the common symbols are treated as undefinedreferences. For more details on common symbols, see the discussion of–warn-common in Section “Linker options” in The GNU linker. The lower
case c character is used when the symbol is in a special section for small
commons.
The symbol is in the initialized data section.
The symbol is in an initialized data section for small objects. Some object
file formats permit more efficient access to small data objects, such as a
global int variable as opposed to a large global array.

i

For PE format files this indicates that the symbol is in a section specific to
the implementation of DLLs.
For ELF format files this indicates that the symbol is an indirect function.
This is a GNU extension to the standard set of ELF symbol types. It
indicates a symbol which if referenced by a relocation does not evaluate toits address, but instead must be invoked at runtime. The runtime execution
will then return the value to be used in the relocation.
Note - the actual symbols display for GNU indirect symbols is controlled by
the --ifunc-chars command line option. If this option has been provided
then the first character in the string will be used for global indirect function
symbols. If the string contains a second character then that will be used
for local indirect function symbols.

I

The symbol is an indirect reference to another symbol.

N

The symbol is a debugging symbol.

n

The symbol is in a non-data, non-code, non-debug read-only section.

p

The symbol is in a stack unwind section.

Rr

The symbol is in a read only data section.

Ss

The symbol is in an uninitialized or zero-initialized data section for small
objects.

Tt

The symbol is in the text (code) section.

U

The symbol is undefined.

u

The symbol is a unique global symbol. This is a GNU extension to thestandard 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 thisname and type in use.

Chapter 3: nm

V
v

W
w

12

The symbol is a weak object. When a weak defined symbol is linked with anormal defined symbol, the normal defined symbol is used with no error.
When a weak undefined symbol is linked and the symbol is not defined, thevalue of the weak symbol becomes zero with no error. On some systems,
uppercase indicates that a default value has been specified.
The symbol is a weak symbol that has not been specifically tagged as a
weak object symbol. When a weak defined symbol is linked with a normal
defined symbol, the normal defined symbol is used with no error. When aweak undefined symbol is linked and the symbol is not defined, the value ofthe symbol is determined in a system-specific manner without error. On
some systems, uppercase indicates that a default value has been specified.

-

The symbol is a stabs symbol in an a.out object file. In this case, the next
values printed are the stabs other field, the stabs desc field, and the stab
type. Stabs symbols are used to hold debugging information.

?

The symbol type is unknown, or object file format specific.

• The symbol name. If a symbol has version information associated with it, then theversion information is displayed as well. If the versioned symbol is undefined or hiddenfrom linker, the version string is displayed as a suffix to the symbol name, precededby an @ character. For example ‘foo@VER_1’. If the version is the default version to
be used when resolving unversioned references to the symbol, then it is displayed as asuffix preceded by two @ characters. For example ‘foo@@VER_2’.
The long and short forms of options, shown here as alternatives, are equivalent.
-A-o--print-file-name
Precede each symbol by the name of the input file (or archive member) in which
it was found, rather than identifying the input file once only, before all of its
symbols.
-a--debug-syms
Display all symbols, even debugger-only symbols; normally these are not listed.
-B

The same as --format=bsd (for compatibility with the MIPS nm).

-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. See Chapter 10 [c++filt], page 60, for more
information on demangling.

Chapter 3: nm

13--no-demangle
Do not demangle low-level symbol names. This is the default.
--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 ofrecursion it is possible to create strings whose decoding will exhaust the amountof stack space available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion to 2048 levelsof nesting.
The default is for this limit to be enabled, but disabling it may be necessary inorder to demangle truly complicated names. Note however that if the recursion
limit is disabled then stack exhaustion is possible and any bug reports aboutsuch an event will be rejected.
-D--dynamic
Display the dynamic symbols rather than the normal symbols. This is only
meaningful for dynamic objects, such as certain types of shared libraries.
-f format--format=format
Use the output format format, which can be bsd, sysv, posix or just-symbols.
The default is bsd. Only the first character of format is significant; it can beeither upper or lower case.
-g--extern-only
Display only external symbols.
-h--helpShow a summary of the options to nm and exit.

--ifunc-chars=CHARS
When display GNU indirect function symbols nm will default to using the icharacter for both local indirect functions and global indirect functions. The--ifunc-chars option allows the user to specify a string containing one or two
characters. The first character will be used for global indirect function symbols
and the second character, if present, will be used for local indirect function
symbols.
j

The same as --format=just-symbols.

-l--line-numbers
For each symbol, use debugging information to try to find a filename and line
number. For a defined symbol, look for the line number of the address of thesymbol. For an undefined symbol, look for the line number of a relocation entryChapter 3: nm

14which refers to the symbol. If line number information can be found, print it
after the other symbol information.
--inlines
When option -l is active, if the address belongs to a function that was inlined,
then this option causes the source information for all enclosing scopes backto the first non-inlined function to be printed as well. For example, if main
inlines callee1 which inlines callee2, and address is from callee2, the source
information for callee1 and main will also be printed.
-n-v--numeric-sort
Sort symbols numerically by their addresses, rather than alphabetically by theirnames.
-p--no-sort
Do not bother to sort the symbols in any order; print them in the orderencountered.
-P--portability
Use the POSIX.2 standard output format instead of the default format. Equivalent to ‘-f posix’.
-r--reverse-sort
Reverse the order of the sort (whether numeric or alphabetic); let the last comefirst.
-S--print-size
Print both value and size of defined symbols for the bsd output style. This
option has no effect for object formats that do not record symbol sizes, unless‘--size-sort’ is also used in which case a calculated size is displayed.
-s--print-armap
When listing symbols from archive members, include the index: a mapping(stored in the archive by ar or ranlib) of which modules contain definitions forwhich names.
-t radix--radix=radix
Use radix as the radix for printing the symbol values. It must be ‘d’ for decimal,‘o’ for octal, or ‘x’ for hexadecimal.
-u--undefined-only
Display only undefined symbols (those external to each object file). By default
both defined and undefined symbols are displayed.

Chapter 3: nm

15-U--defined-only
Display only defined symbols for each object file. By default both defined andundefined symbols are displayed.
-V--version
Show the version number of nm and exit.
-X

This option is ignored for compatibility with the AIX version of nm. It takes
one parameter which must be the string 32_64. The default mode of AIX nm
corresponds to -X 32, which is not supported by gnu nm.

--plugin nameLoad the plugin called name to add support for extra target types. This option
is only available if the toolchain has been built with plugin support enabled.
If --plugin is not provided, but plugin support has been enabled then nm
iterates over the files in ${libdir}/bfd-plugins in alphabetic order and thefirst plugin that claims the object in question is used.
Please note that this plugin search directory is not the one used by ld’s -plugin
option. In order to make nm use the linker plugin it must be copied into the${libdir}/bfd-plugins directory. For GCC based compilations the linker
plugin is called liblto_plugin.so.0.0.0. For Clang based compilations it iscalled LLVMgold.so. The GCC plugin is always backwards compatible withearlier versions, so it is sufficient to just copy the newest one.
--size-sort
Sort symbols by size. For ELF objects symbol sizes are read from the ELF, forother object types the symbol sizes are computed as the difference between thevalue of the symbol and the value of the symbol with the next higher value. If
the bsd output format is used the size of the symbol is printed, rather than thevalue, and ‘-S’ must be used in order both size and value to be printed.
Note - this option does not work if --undefined-only has been enabled as
undefined symbols have no size.
--special-syms
Display symbols which have a target-specific special meaning. These symbols
are usually used by the target for some special processing and are not normally
helpful when included in the normal symbol lists. For example for ARM targets
this option would skip the mapping symbols used to mark transitions between
ARM code, THUMB code and data.
--synthetic
Include synthetic symbols in the output. These are special symbols created by
the linker for various purposes. They are not shown by default since they are
not part of the binary’s original source code.
--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

Chapter 3: nm

16--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) andthe --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.
-W--no-weak
Do not display weak symbols.
--with-symbol-versions--without-symbol-versions
Enables or disables the display of symbol version information. The version
string is displayed as a suffix to the symbol name, preceded by an @ character.
For example ‘foo@VER_1’. If the version is the default version to be used whenresolving unversioned references to the symbol then it is displayed as a suffix
preceded by two @ characters. For example ‘foo@@VER_2’. By default, symbol
version information is displayed.
--target=bfdname
Specify an object code format other than your system’s default format. See
Section 18.1 [Target Selection], page 91, for more information.

17

4 objcopy
objcopy [-F bfdname|--target=bfdname][-I bfdname|--input-target=bfdname][-O bfdname|--output-target=bfdname][-B bfdarch|--binary-architecture=bfdarch][-S|--strip-all][-g|--strip-debug][--strip-unneeded][-K symbolname|--keep-symbol=symbolname][--keep-file-symbols][--keep-section-symbols][-N symbolname|--strip-symbol=symbolname][--strip-unneeded-symbol=symbolname][-G symbolname|--keep-global-symbol=symbolname][--localize-hidden][-L symbolname|--localize-symbol=symbolname][--globalize-symbol=symbolname][--globalize-symbols=filename][-W symbolname|--weaken-symbol=symbolname][-w|--wildcard][-x|--discard-all][-X|--discard-locals][-b byte|--byte=byte][-i [breadth]|--interleave[=breadth]][--interleave-width=width][-j sectionpattern|--only-section=sectionpattern][-R sectionpattern|--remove-section=sectionpattern][--keep-section=sectionpattern][--remove-relocations=sectionpattern][--strip-section-headers][-p|--preserve-dates][-D|--enable-deterministic-archives][-U|--disable-deterministic-archives][--debugging][--gap-fill=val][--pad-to=address][--set-start=val][--adjust-start=incr][--change-addresses=incr][--change-section-address sectionpattern{=,+,-}val][--change-section-lma sectionpattern{=,+,-}val][--change-section-vma sectionpattern{=,+,-}val][--change-warnings] [--no-change-warnings][--set-section-flags sectionpattern=flags][--set-section-alignment sectionpattern=align][--add-section sectionname=filename][--dump-section sectionname=filename][--update-section sectionname=filename][--rename-section oldname=newname[,flags]][--long-section-names {enable,disable,keep}][--change-leading-char] [--remove-leading-char][--reverse-bytes=num][--srec-len=ival] [--srec-forceS3][--redefine-sym old=new][--redefine-syms=filename][--weaken][--keep-symbols=filename][--strip-symbols=filename]Chapter 4: objcopy

18[--strip-unneeded-symbols=filename][--keep-global-symbols=filename][--localize-symbols=filename][--weaken-symbols=filename][--add-symbol name=[section:]value[,flags]][--alt-machine-code=index][--prefix-symbols=string][--prefix-sections=string][--prefix-alloc-sections=string][--add-gnu-debuglink=path-to-file][--only-keep-debug][--strip-dwo][--extract-dwo][--extract-symbol][--writable-text][--readonly-text][--pure][--impure][--file-alignment=num][--heap=reserve[,commit]][--image-base=address][--section-alignment=num][--stack=reserve[,commit]][--subsystem=which:major.minor][--compress-debug-sections][--decompress-debug-sections][--elf-stt-common=val][--merge-notes][--no-merge-notes][--verilog-data-width=val][-v|--verbose][-V|--version][--help] [--info]
infile [outfile]The gnu objcopy utility copies the contents of an object file to another. objcopy uses
the gnu bfd Library to read and write the object files. It can write the destination object
file in a format different from that of the source object file. The exact behavior of objcopy
is controlled by command-line options. Note that objcopy should be able to copy a fully
linked file between any two formats. However, copying a relocatable object file between any
two formats may not work as expected.
objcopy creates temporary files to do its translations and deletes them afterward.
objcopy uses bfd to do all its translation work; it has access to all the formats described in
bfd and thus is able to recognize most formats without being told explicitly. See Section“BFD” in Using LD.
objcopy can be used to generate S-records by using an output target of ‘srec’ (e.g., use‘-O srec’).
objcopy can be used to generate a raw binary file by using an output target of ‘binary’(e.g., use -O binary). When objcopy generates a raw binary file, it will essentially produce a
memory dump of the contents of the input object file. All symbols and relocation information
will be discarded. The memory dump will start at the load address of the lowest section
copied into the output file.

Chapter 4: objcopy

19

When generating an S-record or a raw binary file, it may be helpful to use -S to remove
sections containing debugging information. In some cases -R will be useful to remove sections
which contain information that is not needed by the binary file.
Note—objcopy is not able to change the endianness of its input files. If the input format
has an endianness (some formats do not), objcopy can only copy the inputs into file formats
that have the same endianness or which have no endianness (e.g., ‘srec’). (However, see the--reverse-bytes option.)
infileoutfileThe input and output files, respectively. If you do not specify outfile, objcopy
creates a temporary file and destructively renames the result with the name of
infile.

-I bfdname--input-target=bfdname
Consider the source file’s object format to be bfdname, rather than attempting
to deduce it. See Section 18.1 [Target Selection], page 91, for more information.
-O bfdname--output-target=bfdname
Write the output file using the object format bfdname. See Section 18.1 [Target
Selection], page 91, for more information.
-F bfdname--target=bfdname
Use bfdname as the object format for both the input and the output file;i.e., simply transfer data from source to destination with no translation. See
Section 18.1 [Target Selection], page 91, for more information.
-B bfdarch--binary-architecture=bfdarch
Useful when transforming a architecture-less input file into an object file. In thiscase the output architecture can be set to bfdarch. This option will be ignored
if the input file has a known bfdarch. You can access this binary data inside a
program by referencing the special symbols that are created by the conversion
process. These symbols are called binary objfile start, binary objfile end andbinary objfile size. e.g. you can transform a picture file into an object file andthen access it in your code using these symbols.
-j sectionpattern--only-section=sectionpattern
Copy only the indicated sections from the input file to the output file. This
option may be given more than once. Note that using this option inappropriately may make the output file unusable. Wildcard characters are accepted in
sectionpattern.
If the first character of sectionpattern is the exclamation point (!) then matching
sections will not be copied, even if earlier use of --only-section on the samecommand line would otherwise copy it. For example:--only-section=.text.* --only-section=!.text.foo

will copy all sectinos matching ’.text.*’ but not the section ’.text.foo’.

Chapter 4: objcopy

20-R sectionpattern--remove-section=sectionpattern
Remove any section matching sectionpattern from the output file. This option may be given more than once. Note that using this option inappropriately may make the output file unusable. Wildcard characters are accepted in
sectionpattern. Using both the -j and -R options together results in undefined
behaviour.
If the first character of sectionpattern is the exclamation point (!) then matching
sections will not be removed even if an earlier use of --remove-section on thesame command line would otherwise remove it. For example:--remove-section=.text.* --remove-section=!.text.foo

will remove all sections matching the pattern ’.text.*’, but will not remove thesection ’.text.foo’.
--keep-section=sectionpattern
When removing sections from the output file, keep sections that match
sectionpattern.
--remove-relocations=sectionpattern
Remove non-dynamic relocations from the output file for any section matching
sectionpattern. This option may be given more than once. Note that using thisoption inappropriately may make the output file unusable, and attempting to
remove a dynamic relocation section such as ‘.rela.plt’ from an executableor shared library with --remove-relocations=.plt will not work. Wildcard
characters are accepted in sectionpattern. For example:--remove-relocations=.text.*

will remove the relocations for all sections matching the pattern ’.text.*’.
If the first character of sectionpattern is the exclamation point (!) then matching
sections will not have their relocation removed even if an earlier use of --removerelocations on the same command line would otherwise cause the relocations
to be removed. For example:--remove-relocations=.text.* --remove-relocations=!.text.foo

will remove all relocations for sections matching the pattern ’.text.*’, but will
not remove relocations for the section ’.text.foo’.
--strip-section-headers
Strip section header This option is specific to ELF files. Implies --strip-all
and --merge-notes.
-S--strip-all
Do not copy relocation and symbol information from the source file. Also deletes
debug sections.
-g--strip-debug
Do not copy debugging symbols or sections from the source file.

Chapter 4: objcopy

21--strip-unneeded
Remove all symbols that are not needed for relocation processing in addition to
debugging symbols and sections stripped by --strip-debug.
-K symbolname--keep-symbol=symbolname
When stripping symbols, keep symbol symbolname even if it would normally be
stripped. This option may be given more than once.
-N symbolname--strip-symbol=symbolname
Do not copy symbol symbolname from the source file. This option may be given
more than once.
--strip-unneeded-symbol=symbolname
Do not copy symbol symbolname from the source file unless it is needed by arelocation. This option may be given more than once.
-G symbolname--keep-global-symbol=symbolname
Keep only symbol symbolname global. Make all other symbols local to the file,so that they are not visible externally. This option may be given more than once.
Note: this option cannot be used in conjunction with the --globalize-symbolor --globalize-symbols options.
--localize-hidden
In an ELF object, mark all symbols that have hidden or internal visibility as
local. This option applies on top of symbol-specific localization options such as-L.
-L symbolname--localize-symbol=symbolname
Convert a global or weak symbol called symbolname into a local symbol, so that
it is not visible externally. This option may be given more than once. Note unique symbols are not converted.
-W symbolname--weaken-symbol=symbolname
Make symbol symbolname weak. This option may be given more than once.
--globalize-symbol=symbolname
Give symbol symbolname global scoping so that it is visible outside of the file inwhich it is defined. This option may be given more than once. Note: this option
cannot be used in conjunction with the -G or --keep-global-symbol options.
-w--wildcard
Permit regular expressions in symbolnames used in other command line options.
The question mark (?), asterisk (*), backslash (\) and square brackets ([])
operators can be used anywhere in the symbol name. If the first character ofthe symbol name is the exclamation point (!) then the sense of the switch isreversed for that symbol. For example:-w -W !foo -W fo*

Chapter 4: objcopy

22would cause objcopy to weaken all symbols that start with “fo” except for thesymbol “foo”.
-x--discard-all
Do not copy non-global symbols from the source file.
-X--discard-locals
Do not copy compiler-generated local symbols. (These usually start with ‘L’ or‘.’.)-b byte--byte=byte
If interleaving has been enabled via the --interleave option then start therange of bytes to keep at the byteth byte. byte can be in the range from 0 to
breadth-1, where breadth is the value given by the --interleave option.
-i [breadth]--interleave[=breadth]
Only copy a range out of every breadth bytes. (Header data is not affected).
Select which byte in the range begins the copy with the --byte option. Selectthe width of the range with the --interleave-width option.
This option is useful for creating files to program rom. It is typically used withan srec output target. Note that objcopy will complain if you do not specify
the --byte option as well.
The default interleave breadth is 4, so with --byte set to 0, objcopy would
copy the first byte out of every four bytes from the input to the output.
--interleave-width=width
When used with the --interleave option, copy width bytes at a time. The
start of the range of bytes to be copied is set by the --byte option, and theextent of the range is set with the --interleave option.
The default value for this option is 1. The value of width plus the byte value
set by the --byte option must not exceed the interleave breadth set by the--interleave option.
This option can be used to create images for two 16-bit flashes interleaved
in a 32-bit bus by passing -b 0 -i 4 --interleave-width=2 and -b 2 -i 4--interleave-width=2 to two objcopy commands. If the input was ’12345678’
then the outputs would be ’1256’ and ’3478’ respectively.
-p--preserve-dates
Set the access and modification dates of the output file to be the same as thoseof the input file.
This option also copies the date stored in a PE format file’s header, unless the
SOURCE DATE EPOCH environment variable is defined. If it is defined thenthis variable will be used as the date stored in the header, interpreted as thenumber of seconds since the Unix epoch.

Chapter 4: objcopy

23-D--enable-deterministic-archives
Operate in deterministic mode. When copying archive members and writing
the archive index, use zero for UIDs, GIDs, timestamps, and use consistent filemodes for all files.
If binutils was configured with --enable-deterministic-archives, thenthis mode is on by default. It can be disabled with the ‘-U’ option, below.
-U--disable-deterministic-archives
Do not operate in deterministic mode. This is the inverse of the -D option,
above: when copying archive members and writing the archive index, use theiractual UID, GID, timestamp, and file mode values.
This is the default unless binutils was configured with --enabledeterministic-archives.
--debugging
Convert debugging information, if possible. This is not the default because only
certain debugging formats are supported, and the conversion process can betime consuming.
--gap-fill val
Fill gaps between sections with val. This operation applies to the load address(LMA) of the sections. It is done by increasing the size of the section with thelower address, and filling in the extra space created with val.
--pad-to address
Pad the output file up to the load address address. This is done by increasing
the size of the last section. The extra space is filled in with the value specified
by --gap-fill (default zero).
--set-start val
Set the start address (also known as the entry address) of the new file to val.
Not all object file formats support setting the start address.
--change-start incr--adjust-start incr
Change the start address (also known as the entry address) by adding incr. Not
all object file formats support setting the start address.
--change-addresses incr--adjust-vma incr
Change the VMA and LMA addresses of all sections, as well as the start address,by adding incr. Some object file formats do not permit section addresses to bechanged arbitrarily. Note that this does not relocate the sections; if the program
expects sections to be loaded at a certain address, and this option is used tochange the sections such that they are loaded at a different address, the program
may fail.

Chapter 4: objcopy

24--change-section-address sectionpattern{=,+,-}val--adjust-section-vma sectionpattern{=,+,-}val
Set or change both the VMA address and the LMA address of any section
matching sectionpattern. If ‘=’ is used, the section address is set to val. Otherwise,
val is added to or subtracted from the section address. See the comments under--change-addresses, above. If sectionpattern does not match any sections in
the input file, a warning will be issued, unless --no-change-warnings is used.
--change-section-lma sectionpattern{=,+,-}val
Set or change the LMA address of any sections matching sectionpattern. The
LMA address is the address where the section will be loaded into memory at
program load time. Normally this is the same as the VMA address, which isthe address of the section at program run time, but on some systems, especiallythose where a program is held in ROM, the two can be different. If ‘=’ is used,
the section address is set to val. Otherwise, val is added to or subtracted fromthe section address. See the comments under --change-addresses, above. If
sectionpattern does not match any sections in the input file, a warning will be
issued, unless --no-change-warnings is used.
--change-section-vma sectionpattern{=,+,-}val
Set or change the VMA address of any section matching sectionpattern. The
VMA address is the address where the section will be located once the program
has started executing. Normally this is the same as the LMA address, which isthe address where the section will be loaded into memory, but on some systems,
especially those where a program is held in ROM, the two can be different. If ‘=’is used, the section address is set to val. Otherwise, val is added to or subtracted
from the section address. See the comments under --change-addresses, above.
If sectionpattern does not match any sections in the input file, a warning will
be issued, unless --no-change-warnings is used.
--change-warnings--adjust-warnings
If --change-section-address or --change-section-lma or --changesection-vma is used, and the section pattern does not match any sections,issue a warning. This is the default.
--no-change-warnings--no-adjust-warnings
Do not issue a warning if --change-section-address or --adjust-sectionlma or --adjust-section-vma is used, even if the section pattern does notmatch any sections.
--set-section-flags sectionpattern=flags
Set the flags for any sections matching sectionpattern. The flags argument is
a comma separated string of flag names. The recognized names are ‘alloc’,‘contents’, ‘load’, ‘noload’, ‘readonly’, ‘code’, ‘data’, ‘rom’, ‘exclude’,‘share’, ‘debug’, and ‘large’. You can set the ‘contents’ flag for a section
which does not have contents, but it is not meaningful to clear the ‘contents’flag of a section which does have contents–just remove the section instead. Not
all flags are meaningful for all object file formats. In particular the ‘share’ flag

Chapter 4: objcopy

25

is only meaningful for COFF format files and not for ELF format files. The
ELF x86-64 specific flag ‘large’ corresponds to SHF X86 64 LARGE.
--set-section-alignment sectionpattern=alignSet the alignment for any sections matching sectionpattern. align specifies thealignment in bytes and must be a power of two, i.e. 1, 2, 4, 8. . . .
--add-section sectionname=filename
Add a new section named sectionname while copying the file. The contentsof the new section are taken from the file filename. The size of the section
will be the size of the file. This option only works on file formats which cansupport sections with arbitrary names. Note - it may be necessary to use the--set-section-flags option to set the attributes of the newly created section.
--dump-section sectionname=filename
Place the contents of section named sectionname into the file filename, overwriting any contents that may have been there previously. This option is the inverseof --add-section. This option is similar to the --only-section option exceptthat it does not create a formatted file, it just dumps the contents as raw binary
data, without applying any relocations. The option can be specified more thanonce.
--update-section sectionname=filename
Replace the existing contents of a section named sectionname with the contents
of file filename. The size of the section will be adjusted to the size of the file.
The section flags for sectionname will be unchanged. For ELF format files thesection to segment mapping will also remain unchanged, something which is notpossible using --remove-section followed by --add-section. The option canbe specified more than once.
Note - it is possible to use --rename-section and --update-section to both
update and rename a section from one command line. In this case, pass theoriginal section name to --update-section, and the original and new section
names to --rename-section.
--add-symbol name=[section:]value[,flags]
Add a new symbol named name while copying the file. This option may be
specified multiple times. If the section is given, the symbol will be associatedwith and relative to that section, otherwise it will be an ABS symbol. Specifying
an undefined section will result in a fatal error. There is no check for the value,
it will be taken as specified. Symbol flags can be specified and not all flags will
be meaningful for all object file formats. By default, the symbol will be global.
The special flag ’before=othersym’ will insert the new symbol in front of thespecified othersym, otherwise the symbol(s) will be added at the end of thesymbol table in the order they appear.
--rename-section oldname=newname[,flags]
Rename a section from oldname to newname, optionally changing the section’s
flags to flags in the process. This has the advantage over using a linker script
to perform the rename in that the output stays as an object file and does not
become a linked executable. This option accepts the same set of flags as the--set-section-flags option.

Chapter 4: objcopy

26This option is particularly helpful when the input format is binary, since thiswill always create a section called .data. If for example, you wanted instead tocreate a section called .rodata containing binary data you could use the following
command line to achieve it:
objcopy -I binary -O <output_format> -B <architecture> \--rename-section .data=.rodata,alloc,load,readonly,data,contents \<input_binary_file> <output_object_file>--long-section-names {enable,disable,keep}
Controls the handling of long section names when processing COFF and PE-COFF
object formats. The default behaviour, ‘keep’, is to preserve long section
names if any are present in the input file. The ‘enable’ and ‘disable’ options
forcibly enable or disable the use of long section names in the output object;when ‘disable’ is in effect, any long section names in the input object will betruncated. The ‘enable’ option will only emit long section names if any arepresent in the inputs; this is mostly the same as ‘keep’, but it is left undefined
whether the ‘enable’ option might force the creation of an empty string tablein the output file.
--change-leading-charSome object file formats use special characters at the start of symbols. The
most common such character is underscore, which compilers often add before
every symbol. This option tells objcopy to change the leading character of every
symbol when it converts between object file formats. If the object file formats
use the same leading character, this option has no effect. Otherwise, it will add
a character, or remove a character, or change a character, as appropriate.
--remove-leading-char
If the first character of a global symbol is a special symbol leading character
used by the object file format, remove the character. The most common symbol
leading character is underscore. This option will remove a leading underscorefrom all global symbols. This can be useful if you want to link together objectsof different file formats with different conventions for symbol names. This isdifferent from --change-leading-char because it always changes the symbolname when appropriate, regardless of the object file format of the output file.
--reverse-bytes=num
Reverse the bytes in a section with output contents. A section length must be
evenly divisible by the value given in order for the swap to be able to take place.
Reversing takes place before the interleaving is performed.
This option is used typically in generating ROM images for problematic target
systems. For example, on some target boards, the 32-bit words fetched from
8-bit ROMs are re-assembled in little-endian byte order regardless of the CPU
byte order. Depending on the programming model, the endianness of the ROM
may need to be modified.
Consider a simple file with a section containing the following eight bytes:
12345678.
Using ‘--reverse-bytes=2’ for the above example, the bytes in the output filewould be ordered 21436587.

Chapter 4: objcopy

27

Using ‘--reverse-bytes=4’ for the above example, the bytes in the output filewould be ordered 43218765.
By using ‘--reverse-bytes=2’ for the above example, followed by‘--reverse-bytes=4’ on the output file, the bytes in the second output filewould be ordered 34127856.
--srec-len=ival
Meaningful only for srec output. Set the maximum length of the Srecords being
produced to ival. This length covers both address, data and crc fields.
--srec-forceS3
Meaningful only for srec output. Avoid generation of S1/S2 records, creating
S3-only record format.
--redefine-sym old=new
Change the name of a symbol old, to new. This can be useful when one istrying link two things together for which you have no source, and there arename collisions.
--redefine-syms=filename
Apply --redefine-sym to each symbol pair "old new" listed in the file filename.
filename is simply a flat file, with one symbol pair per line. Line comments may
be introduced by the hash character. This option may be given more than once.
--weaken

Change all global symbols in the file to be weak. This can be useful whenbuilding an object which will be linked against other objects using the -R option
to the linker. This option is only effective when using an object file format
which supports weak symbols.

--keep-symbols=filename
Apply --keep-symbol option to each symbol listed in the file filename. filename
is simply a flat file, with one symbol name per line. Line comments may beintroduced by the hash character. This option may be given more than once.
--strip-symbols=filename
Apply --strip-symbol option to each symbol listed in the file filename. filename
is simply a flat file, with one symbol name per line. Line comments may beintroduced by the hash character. This option may be given more than once.
--strip-unneeded-symbols=filename
Apply --strip-unneeded-symbol option to each symbol listed in the file
filename. filename is simply a flat file, with one symbol name per line. Linecomments may be introduced by the hash character. This option may be given
more than once.
--keep-global-symbols=filename
Apply --keep-global-symbol option to each symbol listed in the file filename.
filename is simply a flat file, with one symbol name per line. Line comments
may be introduced by the hash character. This option may be given more thanonce.

Chapter 4: objcopy

28--localize-symbols=filename
Apply --localize-symbol option to each symbol listed in the file filename.
filename is simply a flat file, with one symbol name per line. Line comments
may be introduced by the hash character. This option may be given more thanonce.
--globalize-symbols=filename
Apply --globalize-symbol option to each symbol listed in the file filename.
filename is simply a flat file, with one symbol name per line. Line comments
may be introduced by the hash character. This option may be given morethan once. Note: this option cannot be used in conjunction with the -G or--keep-global-symbol options.
--weaken-symbols=filename
Apply --weaken-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may
be introduced by the hash character. This option may be given more than once.
--alt-machine-code=index
If the output architecture has alternate machine codes, use the indexth code
instead of the default one. This is useful in case a machine is assigned an
official code and the tool-chain adopts the new code, but other applications still
depend on the original code being used. For ELF based architectures if theindex alternative does not exist then the value is treated as an absolute number
to be stored in the e machine field of the ELF header.
--writable-text
Mark the output text as writable. This option isn’t meaningful for all object
file formats.
--readonly-text
Make the output text write protected. This option isn’t meaningful for all object
file formats.
--pureMark the output file as demand paged. This option isn’t meaningful for all
object file formats.

--impureMark the output file as impure. This option isn’t meaningful for all object fileformats.

--prefix-symbols=string
Prefix all symbols in the output file with string.
--prefix-sections=string
Prefix all section names in the output file with string.
--prefix-alloc-sections=string
Prefix all the names of all allocated sections in the output file with string.
--add-gnu-debuglink=path-to-file
Creates a .gnu debuglink section which contains a reference to path-to-file andadds it to the output file. Note: the file at path-to-file must exist. Part of theprocess of adding the .gnu debuglink section involves embedding a checksum of
the contents of the debug info file into the section.

Chapter 4: objcopy

29

If the debug info file is built in one location but it is going to be installed at
a later time into a different location then do not use the path to the installed
location. The --add-gnu-debuglink option will fail because the installed filedoes not exist yet. Instead put the debug info file in the current directory anduse the --add-gnu-debuglink option without any directory components, likethis:
objcopy --add-gnu-debuglink=foo.debug

At debug time the debugger will attempt to look for the separate debug info filein a set of known locations. The exact set of these locations varies depending
upon the distribution being used, but it typically includes:* The same directory as the executable.
* A sub-directory of the directory containing the executablecalled .debug* A global debug directory such as /usr/lib/debug.
As long as the debug info file has been installed into one of these locations before
the debugger is run everything should work correctly.
--keep-section-symbils
When stripping a file, perhaps with --strip-debug or --strip-unneeded,retain any symbols specifying section names, which would otherwise get stripped.
--keep-file-symbols
When stripping a file, perhaps with --strip-debug or --strip-unneeded,retain any symbols specifying source file names, which would otherwise get
stripped.
--only-keep-debug
Strip a file, removing contents of any sections that would not be stripped by--strip-debug and leaving the debugging sections intact. In ELF files, thispreserves all note sections in the output.
Note - the section headers of the stripped sections are preserved, including theirsizes, but the contents of the section are discarded. The section headers arepreserved so that other tools can match up the debuginfo file with the real
executable, even if that executable has been relocated to a different address
space.
The intention is that this option will be used in conjunction with --add-gnudebuglink to create a two part executable. One a stripped binary which will
occupy less space in RAM and in a distribution and the second a debugging
information file which is only needed if debugging abilities are required. The
suggested procedure to create these files is as follows:
1. Link the executable as normal. Assuming that it is called foo then...
2. Run objcopy --only-keep-debug foo foo.dbg to create a file containing
the debugging info.
3. Run objcopy --strip-debug foo to create a stripped executable.
4. Run objcopy --add-gnu-debuglink=foo.dbg foo to add a link to the
debugging info into the stripped executable.

Chapter 4: objcopy

30

Note—the choice of .dbg as an extension for the debug info file is arbitrary.
Also the --only-keep-debug step is optional. You could instead do this:
1. Link the executable as normal.
2. Copy foo to foo.full
3. Run objcopy --strip-debug foo
4. Run objcopy --add-gnu-debuglink=foo.full foo
i.e., the file pointed to by the --add-gnu-debuglink can be the full executable.
It does not have to be a file created by the --only-keep-debug switch.
Note—this switch is only intended for use on fully linked files. It does notmake sense to use it on object files where the debugging information may
be incomplete. Besides the gnu debuglink feature currently only supports
the presence of one filename containing debugging information, not multiple
filenames on a one-per-object-file basis.
--strip-dwo
Remove the contents of all DWARF .dwo sections, leaving the remaining debugging sections and all symbols intact. This option is intended for use by thecompiler as part of the -gsplit-dwarf option, which splits debug information
between the .o file and a separate .dwo file. The compiler generates all debug
information in the same file, then uses the --extract-dwo option to copy the.dwo sections to the .dwo file, then the --strip-dwo option to remove thosesections from the original .o file.
--extract-dwo
Extract the contents of all DWARF .dwo sections. See the --strip-dwo option
for more information.
--file-alignment num
Specify the file alignment. Sections in the file will always begin at file offsets
which are multiples of this number. This defaults to 512. [This option is specific
to PE targets.]--heap reserve--heap reserve,commit
Specify the number of bytes of memory to reserve (and optionally commit) to
be used as heap for this program. [This option is specific to PE targets.]--image-base value
Use value as the base address of your program or dll. This is the lowest memory
location that will be used when your program or dll is loaded. To reduce theneed to relocate and improve performance of your dlls, each should have aunique base address and not overlap any other dlls. The default is 0x400000 for
executables, and 0x10000000 for dlls. [This option is specific to PE targets.]--section-alignment num
Sets the section alignment field in the PE header. Sections in memory will
always begin at addresses which are a multiple of this number. Defaults to0x1000. [This option is specific to PE targets.]

Chapter 4: objcopy

31--stack reserve--stack reserve,commit
Specify the number of bytes of memory to reserve (and optionally commit) to
be used as stack for this program. [This option is specific to PE targets.]--subsystem which--subsystem which:major--subsystem which:major.minor
Specifies the subsystem under which your program will execute. The legal values
for which are native, windows, console, posix, efi-app, efi-bsd, efi-rtd,
sal-rtd, and xbox. You may optionally set the subsystem version also. Numericvalues are also accepted for which. [This option is specific to PE targets.]--extract-symbol
Keep the file’s section flags and symbols but remove all section data. Specifically,
the option:• removes the contents of all sections;• sets the size of every section to zero; and• sets the file’s start address to zero.
This option is used to build a .sym file for a VxWorks kernel. It can also be auseful way of reducing the size of a --just-symbols linker input file.
--compress-debug-sections
Compress DWARF debug sections using zlib with SHF COMPRESSED fromthe ELF ABI. Note - if compression would actually make a section larger, thenit is not compressed.
--compress-debug-sections=none--compress-debug-sections=zlib--compress-debug-sections=zlib-gnu--compress-debug-sections=zlib-gabi--compress-debug-sections=zstd
For ELF files, these options control how DWARF debug sections
are compressed.
--compress-debug-sections=none is equivalent to--decompress-debug-sections.
--compress-debug-sections=zlib and--compress-debug-sections=zlib-gabi are equivalent to --compressdebug-sections.
--compress-debug-sections=zlib-gnu compresses
DWARF debug sections using the obsoleted zlib-gnu format. The debug sections
are renamed to begin with ‘.zdebug’. --compress-debug-sections=zstd
compresses DWARF debug sections using zstd. Note - if compression would
actually make a section larger, then it is not compressed nor renamed.
--decompress-debug-sections
Decompress DWARF debug sections. For a ‘.zdebug’ section, the original nameis restored.
--elf-stt-common=yes--elf-stt-common=no
For ELF files, these options control whether common symbols should be converted to the STT_COMMON or STT_OBJECT type. --elf-stt-common=yes con-

Chapter 4: objcopy

32

verts common symbol type to STT_COMMON. --elf-stt-common=no converts
common symbol type to STT_OBJECT.
--merge-notes--no-merge-notes
For ELF files, attempt (or do not attempt) to reduce the size of any SHT NOTE
type sections by removing duplicate notes.
-V--version
Show the version number of objcopy.
--verilog-data-width=bytes
For Verilog output, this options controls the number of bytes converted for each
output data element. The input target controls the endianness of the conversion.
-v--verbose
Verbose output: list all object files modified. In the case of archives, ‘objcopy-V’ lists all members of the archive.
--helpShow a summary of the options to objcopy.

--infoDisplay a list showing all architectures and object formats available.

33

5 objdump

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][-Z|--decompress][-W[lLiaprmfFsoORtUuTgAck]|--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=framesinterp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr[-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]Chapter 5: objdump

34[--disassembler-color=[off|terminal|on|extended][-U method] [--unicode=method][-V|--version][-H|--help]
objfile...

objdump displays information about one or more object files. The options control whatparticular 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,-P,-r,-R,-s,-S,-t,-T,-V,-x
must be given.
-a--archive-header
If any of the objfile files are archives, display the archive header information (ina 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.
--adjust-vma=offset
When dumping information, first add offset to all the section addresses. Thisis 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--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.odisplays summary information from the section headers (-h) of fu.o, whichis 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
Section 18.1 [Target Selection], page 91, for more information.
-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. See Chapter 10 [c++filt], page 60, for more
information on demangling.

Chapter 5: objdump

35--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 ofrecursion it is possible to create strings whose decoding will exhaust the amountof stack space available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion to 2048 levelsof nesting.
The default is for this limit to be enabled, but disabling it may be necessary inorder to demangle truly complicated names. Note however that if the recursion
limit is disabled then stack exhaustion is possible and any bug reports aboutsuch an event will be rejected.
-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.
-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.
-D--disassemble-all
Like -d, but disassemble the contents of all non-empty non-bss sections, notjust those expected to contain instructions. -j may be used to select specificsections.
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Chapter 5: objdump

36

however this assumption is supressed. 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.
--no-addresses
When disassembling, don’t print addresses on each line or for symbols andrelocation offsets. In combination with --no-show-raw-insn this may be usefulfor comparing compiler output.
--prefix-addresses
When disassembling, print the complete address on each line. This is the older
disassembly format.
-EB-EL--endian={big|little}
Specify the endianness of the object files. This only affects disassembly. This canbe 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 thefile 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 wereskipped and the file offset of the location from where the disassembly resumes.
When dumping sections, display the file offset of the location from where thedump starts.
--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.
-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 thosesituations, although ld relocates the sections correctly, using ‘objdump -h’ toChapter 5: objdump

37

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.
-H--help-i--infoPrint 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--section=name
Display information for section name. This option may be specified multiple
times.
-L--process-links
Display the contents of non-debug sections found in separate debuginfo files thatare 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 sourceline numbers corresponding to the object code or relocs shown. Only usefulwith -d, -D, or -r.
-m machine--architecture=machine
Specify the architecture to use when disassembling object files. This can be usefulwhen disassembling object files which do not describe architecture information,such as S-records. You can list the available architectures with the -i option.
For most architectures it is possible to supply an architecture name and amachine name, separated by a colon. For example ‘foo:bar’ would refer to the‘bar’ machine type in the ‘foo’ architecture. This can be helpful if objdump has
been configured to support multiple architectures.
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 todisassemble all the instructions use -marm.
-M options--disassembler-options=options
Pass target specific information to the disassembler. Only supported on sometargets. If it is necessary to specify more than one disassembler option thenChapter 5: objdump

38

multiple -M options can be used or can be placed together into a comma separated
list.
For ARC, dsp controls the printing of DSP instructions, spfp selects the printingof FPX single precision FP instructions, dpfp selects the printing of FPX double
precision FP instructions, quarkse_em selects the printing of special QuarkSEEM instructions, fpuda selects the printing of double precision assist instructions,fpus selects the printing of FPU single precision FP instructions, while fpud
selects the printing of FPU double precision FP instructions. Additionally, one
can choose to have all the immediates printed in hexadecimal using hex. By
default, the short immediates are printed using the decimal representation, while
the long immediate values are printed as hexadecimal.
cpu=... allows one to enforce a particular ISA when disassembling instructions,overriding the -m value or whatever is in the ELF file. This might be useful
to select ARC EM or HS ISA, because architecture is same for those anddisassembler relies on private ELF header data to decide if code is for EM or
HS. This option might be specified multiple times - only the latest value will be
used. Valid values are same as for the assembler -mcpu=... 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 enabledby -M reg-names-atpcs and -M reg-names-special-atpcs which use the
ARM/Thumb Procedure Call Standard naming conventions. (Either with thenormal 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 AArch64 targets this switch can be used to set whether instructions are
disassembled as the most general instruction using the -M no-aliases option orwhether instruction notes should be generated as comments in the disasssembly
using -M notes.
For the x86, some of the options duplicate functions of the -m switch, but allow
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.

Chapter 5: objdump

39

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

suffixSpecify the default address size and operand size. These five options
will be overridden if x86-64, i386 or i8086 appear later in theoption string.
When in AT&T mode and also for a limited set of instructions
when in Intel mode, instructs the disassembler to print a mnemonic
suffix even when the suffix could be inferred by the operands or, forcertain instructions, the execution mode’s defaults.

For PowerPC, the -M argument raw selects disasssembly of hardware insns rather
than aliases. For example, you will see rlwinm rather than clrlwi, and addi
rather than li. All of the -m arguments for gas that select a CPU are supported.
These 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. In addition, altivec, any, lsp,
htm, vsx, spe and spe2 add capabilities to a previous or later CPU selection.
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 thedisassembly you expect. If you disassemble without giving a CPU selection, adefault will be chosen from information gleaned by BFD from the object files
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. Multiple selections from thefollowing may be specified as a comma separated string, and invalid options are
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.

Chapter 5: objdump

40

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 thannames.
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 thearchitecture 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 is specific to the object file format. The exact information
printed depends upon the object file format. For some object file formats, noadditional information is printed.
-P options--private=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 isdisplayed with the help).
For XCOFF, the available options are:headerChapter 5: objdump

41

aout
sections
syms
relocslineno,loaderexcepttypchktracebacktoc
ldinfoFor PE, the available options are:headersections
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 used with -d or -D, the relocations are
printed interspersed with the disassembly.

-R--dynamic-reloc
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 usedwith -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. By
default any compressed section will be displayed in its compressed form. In order
to see the contents in a decompressed form add the -Z option to the commandline.
-S--source

Display source code intermixed with disassembly, if possible. Implies -d.

--show-all-symbols
When disassembling, show all the symbols that match a given address, not justthe first one.
--source-comment[=txt]
Like the -S option, but all source code lines are displayed with a prefix of txt.
Typically txt will be a comment string which can be used to distinguish theChapter 5: objdump

42

assembler code from the source code. If txt is not provided then a default stringof “# “ (hash followed by a space), will be used.
--prefix=prefix
Specify prefix to add to the absolute paths when used with -S.
--prefix-strip=level
Indicate how many initial directory names to strip off the hardwired absolute
paths. It has no effect without --prefix=prefix.
--show-raw-insn
When disassembling instructions, print the instruction in hex as well as insymbolic form. This is the default except when --prefix-addresses is used.
--no-show-raw-insn
When disassembling instructions, do not print the instruction bytes. This is thedefault 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 tothe output using simple terminal colors. Alternatively the =extended-color
argument will add color using 8bit colors, but these might not work on all
terminals.
If it is necessary to disable the visualize-jumps option after it has previously
been enabled then use visualize-jumps=off.
--disassembler-color=off--disassembler-color=terminal--disassembler-color=on|color|colour--disassembler-color=extened|extended-color|extened-colour
Enables or disables the use of colored syntax highlighting in disassembly output.
The default behaviour is determined via a configure time option. Note, not
all architectures support colored syntax highlighting, and depending upon theterminal used, colored output may not actually be legible.
The on argument adds colors using simple terminal colors.
The terminal argument does the same, but only if the output device is aterminal.
The extended-color argument is similar to the on argument, 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,=framesinterp,=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 are automatically decompressed (temporarily) beforeChapter 5: objdump

43

they are displayed. If one or more of the optional letters or words follows theswitch then only those type(s) of data will be dumped. The letters and words
refer to the following information: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‘.debug_tu_index’ sections.
f=framesthe‘.debug_cu_index’

and/or

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

k
=links

Displays the contents of the ‘.debug_info’ section. Note: theoutput from this option can also be restricted by the use of the--dwarf-depth and --dwarf-start options.
Displaysthecontentsofthe‘.gnu_debuglink’,‘.gnu_debugaltlink’ and ‘.debug_sup’ sections, if any ofthem are present. Also displays any links to separate dwarf object
files (dwo), if they are 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 foundin linked, separate debug info file(s). This can result in multiple
versions of the same debug section being displayed if it exists inmore than one file.
In addition, when displaying DWARF attributes, if a form is foundthat 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 chosenwhen configuring the binutils via the --enable-follow-debuglinks=yes or --enable-follow-debug-links=no options. If theseChapter 5: objdump

44

are not 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 toresolve. This behaviour can be disabled via the =do-not-usedebuginfod 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 is a need to follow
debug links. This is the default behaviour.
E=do-not-use-debuginfod
Disables contacting debuginfod servers when there is 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=macroo=loc

Displays the contents‘.debug_macinfo’ sections.

of

the

Displaysthecontents‘.debug_loclists’ sections.

of

the

‘.debug_macro’

and/or‘.debug_loc’

and/orO=str-offsets
Displays the contents of the ‘.debug_str_offsets’ section.
p=pubnames
Displays the contents of the‘.debug_gnu_pubnames’ sections.
r=aranges
R=Ranges‘.debug_pubnames’

and/or

Displays the contents of the ‘.debug_aranges’ section.
Displays the contents of‘.debug_rnglists’ sections.

the‘.debug_ranges’

and/orChapter 5: objdump

s
=str
t
=pubtype45

Displays the contents of the ‘.debug_str’, ‘.debug_line_str’
and/or ‘.debug_str_offsets’ sections.
Displays the contents of the‘.debug_gnu_pubtypes’ sections.

‘.debug_pubtypes’

and/orT=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.
--dwarf-depth=nLimit the dump of the .debug_info section to n children. This is only usefulwith --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=nPrint 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 themselvescontain many subsections, all of which are displayed in order.
By default, display the name of the section named .ctf, which is the nameemitted by ld.
--ctf-parent=member
If the CTF section contains ambiguously-defined types, it will consist of anarchive of many CTF dictionaries, all inheriting from one dictionary containing
unambiguous types. This member is by default named .ctf, like the section

Chapter 5: objdump

46

containing it, but it is possible to change this name using the ctf_link_set_
memb_name_changer function at link time. When looking at CTF archives thathave 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 theparent.
--sframe[=section]
Display the contents of the specified SFrame section.
By default, display the name of the section named .sframe, which is the nameemitted 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.

--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--symsPrint 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, butthere are two main types. One looks like this:[[4](sec6](sec3)(fl 0x00)(ty1)(fl 0x00)(ty0)(scl0)(scl3) (nx 1) 0x00000000 .bss2) (nx 0) 0x00000000 fred

where the number inside the square brackets is the number of the entry in thesymbol 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 withthe 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 likethis:
00000000 l
00000000 g

d

.bss
.text

00000000 .bss
00000000 fredHere 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 bitsthat are set on the symbol. These characters are described below. Next is thesection 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.

Chapter 5: objdump

47

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 isdisplayed.
The flag characters are divided into 7 groups as follows:lgu!

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 beneither local or global for a variety of reasons, e.g., because it isused 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 asymbol 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 (aspace).

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

d
D

The symbol is an indirect reference to another symbol (I), a function
to be evaluated during reloc processing (i) or a normal symbol (aspace).
The symbol is a debugging symbol (d) or a dynamic symbol (D) or
a normal symbol (a space).

F
fO

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, exceptthat 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.

Chapter 5: objdump

48--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) andthe --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.
-w--wideFormat 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.
-Z--decompress
The -Z option is meant to be used in conunction with the -s option. It instructs
objdump to decompress any compressed sections before displaying their contents.

49

6 ranlibranlib [--plugin name] [-DhHvVt] archive

ranlib generates an index to the contents of an archive and stores it in the archive. The
index lists each symbol defined by a member of an archive that is a relocatable object file.
You may use ‘nm -s’ or ‘nm --print-armap’ to list this index.
An archive with such an index speeds up linking to the library and allows routines in thelibrary to call each other without regard to their placement in the archive.
The gnu ranlib program is another form of gnu ar; running ranlib is completely
equivalent to executing ‘ar -s’. See Chapter 1 [ar], page 1.
-h-H--helpShow usage information for ranlib.

-v-V--version
Show the version number of ranlib.
-D

Operate in deterministic mode. The symbol map archive member’s header willshow zero for the UID, GID, and timestamp. When this option is used, multiple
runs will produce identical output files.
If binutils was configured with --enable-deterministic-archives, thenthis mode is on by default. It can be disabled with the ‘-U’ option, described
below.

-t

Update the timestamp of the symbol map of an archive.

-U

Do not operate in deterministic mode. This is the inverse of the ‘-D’ option,
above: the archive index will get actual UID, GID, timestamp, and file mode
values.
If binutils was configured without --enable-deterministic-archives, thenthis mode is on by default.

50

7 sizesize [-A|-B|-G|--format=compatibility][--help][-d|-o|-x|--radix=number][--common][-t|--totals][--target=bfdname] [-V|--version][-f][objfile...]

The gnu size utility lists the section sizes and the total size for each of the binary files
objfile on its argument list. By default, one line of output is generated for each file or each
module if the file is an archive.
objfile . . . are the files to be examined. If none are specified, the file a.out will be usedinstead.
The command-line options have the following meanings:-A-B-G--format=compatibility
Using one of these options, you can choose whether the output from gnu
size resembles output from System V size (using -A, or --format=sysv), or
Berkeley size (using -B, or --format=berkeley). The default is the one-line
format similar to Berkeley’s. Alternatively, you can choose the GNU format
output (using -G, or --format=gnu), this is similar to Berkeley’s output format,
but sizes are counted differently.
Here is an example of the Berkeley (default) format of output from size:$ size --format=Berkeley ranlib size
text
data
bss
dec
hex filename
29488081920
11592 388392
5ed28 ranlib
29488081920
11888 388688
5ee50 size

The Berkeley style output counts read only data in the text column, not in thedata column, the dec and hex columns both display the sum of the text, data,
and bss columns in decimal and hexadecimal respectively.
The GNU format counts read only data in the data column, not the text
column, and only displays the sum of the text, data, and bss columns once, inthe total column. The --radix option can be used to change the number basefor all columns. Here is the same data displayed with GNU conventions:$ size --format=GNU ranlib size
text
data
bss
27988096920
11592
27988096920
11888

total filename
388392 ranlib
388688 size

This is the same data, but displayed closer to System V conventions:$ size --format=SysV ranlib size
ranlib :section
size
addr
.text
294880
8192
.data
81920
303104.bss
11592
385024

Chapter 7: size

51

Total

388392

size :
section
.text
.data
.bss
Total

size
29488081920
11888
388688addr
8192
303104385024--help-h-H-?

Show a summary of acceptable arguments and options.

-d
-o
-x
--radix=number
Using one of these options, you can control whether the size of each section is
given in decimal (-d, or --radix=10); octal (-o, or --radix=8); or hexadecimal(-x, or --radix=16). In --radix=number, only the three values (8, 10, 16) aresupported. The total size is always given in two radices; decimal and hexadecimalfor -d or -x output, or octal and hexadecimal if you’re using -o.
--common-t--totals

Print total size of common symbols in each file. When using Berkeley or GNU
format these are included in the bss size.
Show totals of all objects listed (Berkeley or GNU format mode only).

--target=bfdname
Specify that the object-code format for objfile is bfdname. This option may not
be necessary; size can automatically recognize many formats. See Section 18.1
[Target Selection], page 91, for more information.
-v-V--version
Display the version number of size.
-fIgnored. This option is used by other versions of the size program, but it is
not supported by the GNU Binutils version.

52

8 strings
strings [-afovV] [-min-len][-n min-len] [--bytes=min-len][-t radix] [--radix=radix][-e encoding] [--encoding=encoding][-U method] [--unicode=method][-] [--all] [--print-file-name][-T bfdname] [--target=bfdname][-w] [--include-all-whitespace][-s] [--output-separator sep_string][--help] [--version] file...

For each file given, gnu strings prints the printable character sequences that are atleast 4 characters long (or the number given with the options below) and are followed by an
unprintable character.
Depending upon how the strings program was configured it will default to either displaying
all the printable sequences that it can find in each file, or only those sequences that are inloadable, initialized data sections. If the file type is unrecognizable, or if strings is readingfrom stdin then it will always display all of the printable sequences that it can find.
For backwards compatibility any file that occurs after a command-line option of just will also be scanned in full, regardless of the presence of any -d option.
strings is mainly useful for determining the contents of non-text files.
-a
--all
-

-d
--dataScan the whole file, regardless of what sections it contains or whether thosesections are loaded or initialized. Normally this is the default behaviour, but
strings can be configured so that the -d is the default instead.
The - option is position dependent and forces strings to perform full scans ofany file that is mentioned after the - on the command line, even if the -d option
has been specified.
Only print strings from initialized, loaded data sections in the file. This may
reduce the amount of garbage in the output, but it also exposes the strings
program to any security flaws that may be present in the BFD library used
to scan and load sections. Strings can be configured so that this option is thedefault behaviour. In such cases the -a option can be used to avoid using the
BFD library and instead just print all of the strings found in the file.

-f--print-file-namePrint the name of the file before each string.
--helpPrint a summary of the program usage on the standard output and exit.

-min-len-n min-len--bytes=min-len
Print sequences of displayable characters that are at least min-len characterslong. If not specified a default minimum length of 4 is used. The distinction

Chapter 8: strings

53

between displayable and non-displayable characters depends upon the setting of
the -e and -U options. Sequences are always terminated at control characterssuch as new-line and carriage-return, but not the tab character.
-oLike ‘-t o’. Some other versions of strings have -o act like ‘-t d’ instead.
Since we can not be compatible with both ways, we simply chose one.

-t radix--radix=radix
Print the offset within the file before each string. The single character argument
specifies the radix of the offset—‘o’ for octal, ‘x’ for hexadecimal, or ‘d’ for
decimal.
-e encoding--encoding=encoding
Select the character encoding of the strings that are to be found. Possible values
for encoding are: ‘s’ = single-7-bit-byte characters (default), ‘S’ = single-8-bitbyte characters, ‘b’ = 16-bit bigendian, ‘l’ = 16-bit littleendian, ‘B’ = 32-bit
bigendian, ‘L’ = 32-bit littleendian. Useful for finding wide character strings.
(‘l’ and ‘b’ apply to, for example, Unicode UTF-16/UCS-2 encodings).
-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, and instead
rely upon the setting of the --encoding option. The other values for this option
automatically enable --encoding=S.
The --unicode=invalid option treats them as non-graphic characters andhence not part of a valid string. All the remaining options treat them as valid
string characters.
The --unicode=locale option displays them in the current locale, which may or
may not support UTF-8 encoding. The --unicode=hex option displays them ashex byte sequences enclosed between <> characters. 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 presenceof unicode sequences where they might not be expected.
-T bfdname--target=bfdname
Specify an object code format other than your system’s default format. See
Section 18.1 [Target Selection], page 91, for more information.
-v-V--version
Print the program version number on the standard output and exit.

Chapter 8: strings

54-w--include-all-whitespace
By default tab and space characters are included in the strings that are displayed,
but other whitespace characters, such a newlines and carriage returns, are not.
The -w option changes this so that all whitespace characters are considered tobe part of a string.
-s--output-separator
By default, output strings are delimited by a new-line. This option allows you
to supply any string to be used as the output record separator. Useful with–include-all-whitespace where strings may contain new-lines internally.

55

9 strip
strip [-F bfdname |--target=bfdname][-I bfdname |--input-target=bfdname][-O bfdname |--output-target=bfdname][-s|--strip-all][-S|-g|-d|--strip-debug][--strip-dwo][-K symbolname|--keep-symbol=symbolname][-M|--merge-notes][--no-merge-notes][-N symbolname |--strip-symbol=symbolname][-w|--wildcard][-x|--discard-all] [-X |--discard-locals][-R sectionname |--remove-section=sectionname][--keep-section=sectionpattern][--remove-relocations=sectionpattern][--strip-section-headers][-o file] [-p|--preserve-dates][-D|--enable-deterministic-archives][-U|--disable-deterministic-archives][--keep-section-symbols][--keep-file-symbols][--only-keep-debug][-v |--verbose] [-V|--version][--help] [--info]
objfile...

gnu strip discards all symbols from object files objfile. The list of object files may
include archives. At least one object file must be given.
strip modifies the files named in its argument, rather than writing modified copies under
different names.
-F bfdname--target=bfdname
Treat the original objfile as a file with the object code format bfdname, andrewrite it in the same format. See Section 18.1 [Target Selection], page 91, formore information.
--helpShow a summary of the options to strip and exit.

--infoDisplay a list showing all architectures and object formats available.

-I bfdname--input-target=bfdname
Treat the original objfile as a file with the object code format bfdname. See
Section 18.1 [Target Selection], page 91, for more information.
-O bfdname--output-target=bfdname
Replace objfile with a file in the output format bfdname. See Section 18.1
[Target Selection], page 91, for more information.
-R sectionname--remove-section=sectionname
Remove any section named sectionname from the output file, in addition towhatever sections would otherwise be removed. This option may be given more

Chapter 9: strip

56

than once. Note that using this option inappropriately may make the output fileunusable. The wildcard character ‘*’ may be given at the end of sectionname.
If so, then any section starting with sectionname will be removed.
If the first character of sectionpattern is the exclamation point (!) then matching
sections will not be removed even if an earlier use of --remove-section on thesame command line would otherwise remove it. For example:--remove-section=.text.* --remove-section=!.text.foo

will remove all sections matching the pattern ’.text.*’, but will not remove thesection ’.text.foo’.
--keep-section=sectionpattern
When removing sections from the output file, keep sections that match
sectionpattern.
--remove-relocations=sectionpattern
Remove relocations from the output file for any section matching sectionpattern.
This option may be given more than once. Note that using this option inappropriately may make the output file unusable. Wildcard characters are accepted
in sectionpattern. For example:--remove-relocations=.text.*

will remove the relocations for all sections matching the patter ’.text.*’.
If the first character of sectionpattern is the exclamation point (!) then matching
sections will not have their relocation removed even if an earlier use of --removerelocations on the same command line would otherwise cause the relocations
to be removed. For example:--remove-relocations=.text.* --remove-relocations=!.text.foo

will remove all relocations for sections matching the pattern ’.text.*’, but will
not remove relocations for the section ’.text.foo’.
--strip-section-headers
Strip section headers. This option is specific to ELF files. Implies --strip-all
and --merge-notes.
-s--strip-all
Remove all symbols.
-g-S-d--strip-debug
Remove debugging symbols only.
--strip-dwo
Remove the contents of all DWARF .dwo sections, leaving the remaining debugging sections and all symbols intact. See the description of this option in theobjcopy section for more information.
--strip-unneeded
Remove all symbols that are not needed for relocation processing in addition to
debugging symbols and sections stripped by --strip-debug.

Chapter 9: strip

57-K symbolname--keep-symbol=symbolname
When stripping symbols, keep symbol symbolname even if it would normally be
stripped. This option may be given more than once.
-M--merge-notes--no-merge-notes
For ELF files, attempt (or do not attempt) to reduce the size of any SHT NOTE
type sections by removing duplicate notes. The default is to attempt thisreduction unless stripping debug or DWO information.
-N symbolname--strip-symbol=symbolname
Remove symbol symbolname from the source file. This option may be given
more than once, and may be combined with strip options other than -K.
Put the stripped output in file, rather than replacing the existing file. When
this argument is used, only one objfile argument may be specified.

-o file-p--preserve-dates
Preserve the access and modification dates of the file.
-D--enable-deterministic-archives
Operate in deterministic mode. When copying archive members and writing
the archive index, use zero for UIDs, GIDs, timestamps, and use consistent filemodes for all files.
If binutils was configured with --enable-deterministic-archives, thenthis mode is on by default. It can be disabled with the ‘-U’ option, below.
-U--disable-deterministic-archives
Do not operate in deterministic mode. This is the inverse of the -D option,
above: when copying archive members and writing the archive index, use theiractual UID, GID, timestamp, and file mode values.
This is the default unless binutils was configured with --enabledeterministic-archives.
-w--wildcard
Permit regular expressions in symbolnames used in other command line options.
The question mark (?), asterisk (*), backslash (\) and square brackets ([])
operators can be used anywhere in the symbol name. If the first character ofthe symbol name is the exclamation point (!) then the sense of the switch isreversed for that symbol. For example:-w -K !foo -K fo*

would cause strip to only keep symbols that start with the letters “fo”, but todiscard the symbol “foo”.

Chapter 9: strip

58-x--discard-all
Remove non-global symbols.
-X--discard-locals
Remove compiler-generated local symbols. (These usually start with ‘L’ or ‘.’.)--keep-section-symbols
When stripping a file, perhaps with --strip-debug or --strip-unneeded,retain any symbols specifying section names, which would otherwise get stripped.
--keep-file-symbols
When stripping a file, perhaps with --strip-debug or --strip-unneeded,retain any symbols specifying source file names, which would otherwise get
stripped.
--only-keep-debug
Strip a file, emptying the contents of any sections that would not be strippedby --strip-debug and leaving the debugging sections intact. In ELF files, thispreserves all the note sections in the output as well.
Note - the section headers of the stripped sections are preserved, including theirsizes, but the contents of the section are discarded. The section headers arepreserved so that other tools can match up the debuginfo file with the real
executable, even if that executable has been relocated to a different address
space.
The intention is that this option will be used in conjunction with --add-gnudebuglink to create a two part executable. One a stripped binary which will
occupy less space in RAM and in a distribution and the second a debugging
information file which is only needed if debugging abilities are required. The
suggested procedure to create these files is as follows:
1. Link the executable as normal. Assuming that it is called foo then...
2. Run objcopy --only-keep-debug foo foo.dbg to create a file containing
the debugging info.
3. Run objcopy --strip-debug foo to create a stripped executable.
4. Run objcopy --add-gnu-debuglink=foo.dbg foo to add a link to the
debugging info into the stripped executable.
Note—the choice of .dbg as an extension for the debug info file is arbitrary.
Also the --only-keep-debug step is optional. You could instead do this:
1. Link the executable as normal.
2. Copy foo to foo.full
3. Run strip --strip-debug foo
4. Run objcopy --add-gnu-debuglink=foo.full foo
i.e., the file pointed to by the --add-gnu-debuglink can be the full executable.
It does not have to be a file created by the --only-keep-debug switch.

Chapter 9: strip

59

Note—this switch is only intended for use on fully linked files. It does notmake sense to use it on object files where the debugging information may
be incomplete. Besides the gnu debuglink feature currently only supports
the presence of one filename containing debugging information, not multiple
filenames on a one-per-object-file basis.
-V--version
Show the version number for strip.
-v--verbose
Verbose output: list all object files modified. In the case of archives, ‘strip -v’lists all members of the archive.

60

10 c++filt
c++filt [-_|--strip-underscore][-n|--no-strip-underscore][-p|--no-params][-t|--types][-i|--no-verbose][-r|--no-recurse-limit][-R|--recurse-limit][-s format|--format=format][--help] [--version] [symbol...]The C++ and Java languages provide function overloading, which means that you canwrite many functions with the same name, providing that each function takes parameters ofdifferent types. In order to be able to distinguish these similarly named functions C++ andJava encode them into a low-level assembler name which uniquely identifies each different
version. This process is known as mangling. The c++filt1 program does the inverse
mapping: it decodes (demangles) low-level names into user-level names so that they can beread.
Every alphanumeric word (consisting of letters, digits, underscores, dollars, or periods)
seen in the input is a potential mangled name. If the name decodes into a C++ name, theC++ name replaces the low-level name in the output, otherwise the original word is output.
In this way you can pass an entire assembler source file, containing mangled names, throughc++filt and see the same source file containing demangled names.
You can also use c++filt to decipher individual symbols by passing them on the commandline:
c++filt symbol
If no symbol arguments are given, c++filt reads symbol names from the standard
input instead. All the results are printed on the standard output. The difference between
reading names from the command line versus reading names from the standard input isthat command-line arguments are expected to be just mangled names and no checking is
performed to separate them from surrounding text. Thus for example:
c++filt -n _Z1fv

will work and demangle the name to “f()” whereas:
c++filt -n _Z1fv,

will not work. (Note the extra comma at the end of the mangled name which makes it
invalid). This command however will work:echo _Z1fv, | c++filt -n

and will display “f(),”, i.e., the demangled name followed by a trailing comma. Thisbehaviour is because when the names are read from the standard input it is expected thatthey might be part of an assembler source file where there might be extra, extraneous
characters trailing after a mangled name. For example:.type_Z1fv, @function-_--strip-underscore
On some systems, both the C and C++ compilers put an underscore in front of
every name. For example, the C name foo gets the low-level name _foo. This
1

MS-DOS does not allow + characters in file names, so on MS-DOS this program is named CXXFILT.

Chapter 10: c++filt

61

option removes the initial underscore. Whether c++filt removes the underscoreby default is target dependent.
-n--no-strip-underscore
Do not remove the initial underscore.
-p--no-params
When demangling the name of a function, do not display the types of thefunction’s parameters.
-t--types

Attempt to demangle types as well as function names. This is disabled by default
since mangled types are normally only used internally in the compiler, and they
can be confused with non-mangled names. For example, a function called “a”
treated as a mangled type name would be demangled to “signed char”.

-i--no-verbose
Do not include implementation details (if any) in the demangled output.
-r-R--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 ofrecursion it is possible to create strings whose decoding will exhaust the amountof stack space available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion to 2048 levelsof nesting.
The default is for this limit to be enabled, but disabling it may be necessary inorder to demangle truly complicated names. Note however that if the recursion
limit is disabled then stack exhaustion is possible and any bug reports aboutsuch an event will be rejected.
The -r option is a synonym for the --no-recurse-limit option. The -R option
is a synonym for the --recurse-limit option.
-s format--format=format
c++filt can decode various methods of mangling, used by different compilers.
The argument to this option selects which method it uses:
auto

Automatic selection based on executable (the default method)gnu

the one used by the gnu C++ compiler (g++)

lucidthe one used by the Lucid compiler (lcc)Chapter 10: c++filt--help62

arm

the one specified by the C++ Annotated Reference Manualhp

the one used by the HP compiler (aCC)

edg

the one used by the EDG compiler

gnu-v3the one used by the gnu C++ compiler (g++) with the V3 ABI.

java

the one used by the gnu Java compiler (gcj)

gnat

the one used by the gnu Ada compiler (GNAT).

Print a summary of the options to c++filt and exit.

--version
Print the version number of c++filt and exit.
Warning: c++filt is a new utility, and the details of its user interface aresubject to change in future releases. In particular, a command-line option may
be required in the future to decode a name passed as an argument on thecommand line; in other words,
c++filt symbol
may in a future release become
c++filt option symbol

63

11 addr2line
addr2line [-a|--addresses][-b bfdname|--target=bfdname][-C|--demangle[=style]][-r|--no-recurse-limit][-R|--recurse-limit][-e filename|--exe=filename][-f|--functions] [-s|--basename][-i|--inlines][-p|--pretty-print][-j|--section=name][-H|--help] [-V|--version][addr addr ...]

addr2line translates addresses or symbol+offset into file names and line numbers. Givenan address or symbol+offset in an executable or an offset in a section of a relocatable object, it
uses the debugging information to figure out which file name and line number are associatedwith it.
The executable or relocatable object to use is specified with the -e option. The default
is the file a.out. The section in the relocatable object to use is specified with the -j option.
addr2line has two modes of operation.
In the first, hexadecimal addresses or symbol+offset are specified on the command line,
and addr2line displays the file name and line number for each address.
In the second, addr2line reads hexadecimal addresses or symbol+offset from standard
input, and prints the file name and line number for each address on standard output. In
this mode, addr2line may be used in a pipe to convert dynamically chosen addresses.
The format of the output is ‘FILENAME:LINENO’. By default each input address generates
one line of output.
Two options can generate additional lines before each ‘FILENAME:LINENO’ line (in thatorder).
If the -a option is used then a line with the input address is displayed.
If the -f option is used, then a line with the ‘FUNCTIONNAME’ is displayed. This is thename of the function containing the address.
One option can generate additional lines after the ‘FILENAME:LINENO’ line.
If the -i option is used and the code at the given address is present there because of
inlining by the compiler then additional lines are displayed afterwards. One or two extra
lines (if the -f option is used) are displayed for each inlined function.
Alternatively if the -p option is used then each input address generates a single, long,output line containing the address, the function name, the file name and the line number. If
the -i option has also been used then any inlined functions will be displayed in the samemanner, but on separate lines, and prefixed by the text ‘(inlined by)’.
If the file name or function name can not be determined, addr2line will print twoquestion marks in their place. If the line number can not be determined, addr2line will
print 0.
When symbol+offset is used, +offset is optional, except when the symbol is ambigious
with a hex number. The resolved symbols can be mangled or unmangled, except unmangled
symbols with + are not allowed.

Chapter 11: addr2line

64

The long and short forms of options, shown here as alternatives, are equivalent.
-a--addresses
Display the address before the function name, file and line number information.
The address is printed with a ‘0x’ prefix to easily identify it.
-b bfdname--target=bfdname
Specify that the object-code format for the object files is bfdname.
-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. See Chapter 10 [c++filt], page 60, for more
information on demangling.
-e filename--exe=filename
Specify the name of the executable for which addresses should be translated.
The default file is a.out.
-f--functions
Display function names as well as file and line number information.
-s--basenames
Display only the base of each file name.
-i--inlines
If the address belongs to a function that was inlined, the source information for
all enclosing scopes back to the first non-inlined function will also be printed.
For example, if main inlines callee1 which inlines callee2, and address is fromcallee2, the source information for callee1 and main will also be printed.
-j--section
Read offsets relative to the specified section instead of absolute addresses.
-p--pretty-print
Make the output more human friendly: each location are printed on one line. If
option -i is specified, lines for all enclosing scopes are prefixed with ‘(inlinedby)’.

Chapter 11: addr2line

65

-r
-R
--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 ofrecursion it is possible to create strings whose decoding will exhaust the amountof stack space available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion to 2048 levelsof nesting.
The default is for this limit to be enabled, but disabling it may be necessary inorder to demangle truly complicated names. Note however that if the recursion
limit is disabled then stack exhaustion is possible and any bug reports aboutsuch an event will be rejected.
The -r option is a synonym for the --no-recurse-limit option. The -R option
is a synonym for the --recurse-limit option.
Note this option is only effective if the -C or --demangle option has beenenabled.

66

12 windmc
windmc may be used to generator Windows message resources.
Warning: windmc is not always built as part of the binary utilities, since it is
only useful for Windows targets.
windmc [options] input-filewindmc reads message definitions from an input file (.mc) and translate them into a setof output files. The output files may be of four kinds:h

A C header file containing the message definitions.

rc

A resource file compilable by the windres tool.

bin

One or more binary files containing the resource data for a specific message
language.

dbg

A C include file that maps message id’s to their symbolic name.

The exact description of these different formats is available in documentation fromMicrosoft.
When windmc converts from the mc format to the bin format, rc, h, and optional dbg it
is acting like the Windows Message Compiler.
-a--ascii_in
Specifies that the input file specified is ASCII. This is the default behaviour.
-A--ascii_out
Specifies that messages in the output bin files should be in ASCII format.
-b--binprefix
Specifies that bin filenames should have to be prefixed by the basename of thesource file.
-c--customflag
Sets the customer bit in all message id’s.
-C codepage--codepage_in codepage
Sets the default codepage to be used to convert input file to UTF16. The default
is ocdepage 1252.
-d--decimal_values
Outputs the constants in the header file in decimal. Default is using hexadecimal
output.
-e ext--extension ext
The extension for the header file. The default is .h extension.

Chapter 12: windmc

67-F target--target target
Specify the BFD format to use for a bin file as output. This is a BFD target
name; you can use the --help option to see a list of supported targets. Normallywindmc will use the default format, which is the first one listed by the --help
option. Section 18.1 [Target Selection], page 91.
-h path--headerdir path
The target directory of the generated header file. The default is the current
directory.
-H--help

Displays a list of command-line options and then exits.

-m characters--maxlength characters
Instructs windmc to generate a warning if the length of any message exceeds thenumber specified.
-n--nullterminate
Terminate message text in bin files by zero. By default they are terminated by
CR/LF.
-o--hresult_use
Not yet implemented. Instructs windmc to generate an OLE2 header file, using
HRESULT definitions. Status codes are used if the flag is not specified.
-O codepage--codepage_out codepage
Sets the default codepage to be used to output text files. The default is ocdepage1252.
-r path--rcdir path
The target directory for the generated rc script and the generated bin files thatthe resource compiler script includes. The default is the current directory.
-u--unicode_in
Specifies that the input file is UTF16.
-U--unicode_out
Specifies that messages in the output bin file should be in UTF16 format. Thisis the default behaviour.
-v--verbose
Enable verbose mode.

Chapter 12: windmc

68-V--version
Prints the version number for windmc.
-x path--xdgb path
The path of the dbg C include file that maps message id’s to the symbolic name.
No such file is generated without specifying the switch.

69

13 windres
windres may be used to manipulate Windows resources.
Warning: windres is not always built as part of the binary utilities, since it is
only useful for Windows targets.
windres [options] [input-file] [output-file]windres reads resources from an input file and copies them into an output file. Either
file may be in one of three formats:rc

A text format read by the Resource Compiler.

res

A binary format generated by the Resource Compiler.

coff

A COFF object or executable.

The exact description of these different formats is available in documentation fromMicrosoft.
When windres converts from the rc format to the res format, it is acting like theWindows Resource Compiler. When windres converts from the res format to the coffformat, it is acting like the Windows CVTRES program.
When windres generates an rc file, the output is similar but not identical to the format
expected for the input. When an input rc file refers to an external filename, an output rc
file will instead include the file contents.
If the input or output format is not specified, windres will guess based on the file name,or, for the input file, the file contents. A file with an extension of .rc will be treated as
an rc file, a file with an extension of .res will be treated as a res file, and a file with anextension of .o or .exe will be treated as a coff file.
If no output file is specified, windres will print the resources in rc format to standard
output.
The normal use is for you to write an rc file, use windres to convert it to a COFF
object file, and then link the COFF file into your application. This will make the resources
described in the rc file available to Windows.
-i filename--input filename
The name of the input file. If this option is not used, then windres will use thefirst non-option argument as the input file name. If there are no non-option
arguments, then windres will read from standard input. windres can not reada COFF file from standard input.
-o filename--output filename
The name of the output file. If this option is not used, then windres will use
the first non-option argument, after any used for the input file name, as theoutput file name. If there is no non-option argument, then windres will write
to standard output. windres can not write a COFF file to standard output.
Note, for compatibility with rc the option -fo is also accepted, but its use is
not recommended.

Chapter 13: windres70-J format--input-format format
The input format to read. format may be ‘res’, ‘rc’, or ‘coff’. If no input
format is specified, windres will guess, as described above.
-O format--output-format format
The output format to generate. format may be ‘res’, ‘rc’, or ‘coff’. If no
output format is specified, windres will guess, as described above.
-F target--target target
Specify the BFD format to use for a COFF file as input or output. This is a
BFD target name; you can use the --help option to see a list of supported
targets. Normally windres will use the default format, which is the first one
listed by the --help option. Section 18.1 [Target Selection], page 91.
--preprocessor program
When windres reads an rc file, it runs it through the C preprocessor first. This
option may be used to specify the preprocessor to use. The default preprocessor
is gcc.
--preprocessor-arg option
When windres reads an rc file, it runs it through the C preprocessor first. This
option may be used to specify additional text to be passed to preprocessor on its
command line. This option can be used multiple times to add multiple options
to the preprocessor command line. If the --preprocessor option has not been
specified then a default set of preprocessor arguments will be used, with any--preprocessor-arg options being placed after them on the command line.
These default arguments are -E, -xc-header and -DRC_INVOKED.
-I directory--include-dir directorySpecify an include directory to use when reading an rc file. windres will passthis to the preprocessor as an -I option. windres will also search this directorywhen looking for files named in the rc file. If the argument passed to thiscommand matches any of the supported formats (as described in the -J option),
it will issue a deprecation warning, and behave just like the -J option. New
programs should not use this behaviour. If a directory happens to match aformat, simple prefix it with ‘./’ to disable the backward compatibility.
-D target--define sym[=val]
Specify a -D option to pass to the preprocessor when reading an rc file.
-U target--undefine sym
Specify a -U option to pass to the preprocessor when reading an rc file.
-r

Ignored for compatibility with rc.

-v

Enable verbose mode. This tells you what the preprocessor is if you didn’t
specify one.

Chapter 13: windres

71-c val--codepage val
Specify the default codepage to use when reading an rc file. val should be ahexadecimal prefixed by ‘0x’ or decimal codepage code. The valid range is fromzero up to 0xffff, but the validity of the codepage is host and configuration
dependent.
-l val--language val
Specify the default language to use when reading an rc file. val should be ahexadecimal language code. The low eight bits are the language, and the higheight bits are the sublanguage.
--use-temp-file
Use a temporary file to instead of using popen to read the output of the
preprocessor. Use this option if the popen implementation is buggy on the host(eg., certain non-English language versions of Windows 95 and Windows 98 are
known to have buggy popen where the output will instead go the console).
--no-use-temp-file
Use popen, not a temporary file, to read the output of the preprocessor. This is
the default behaviour.
-h--helpPrints a usage summary.

-V--version
Prints the version number for windres.
--yydebug
If windres is compiled with YYDEBUG defined as 1, this will turn on parser
debugging.

72

14 dlltool
dlltool is used to create the files needed to create dynamic link libraries (DLLs) on systems
which understand PE format image files such as Windows. A DLL contains an exporttable which contains information that the runtime loader needs to resolve references from areferencing program.
The export table is generated by this program by reading in a .def file or scanning
the .a and .o files which will be in the DLL. A .o file can contain information in special‘.drectve’ sections with export information.
Note: dlltool is not always built as part of the binary utilities, since it is only
useful for those targets which support DLLs.
dlltool [-d|--input-def def-file-name][-b|--base-file base-file-name][-e|--output-exp exports-file-name][-z|--output-def def-file-name][-l|--output-lib library-file-name][-y|--output-delaylib library-file-name][--export-all-symbols] [--no-export-all-symbols][--exclude-symbols list][--no-default-excludes][-S|--as path-to-assembler] [-f|--as-flags options][-D|--dllname name] [-m|--machine machine][-a|--add-indirect][-U|--add-underscore] [--add-stdcall-underscore][-k|--kill-at] [-A|--add-stdcall-alias][-p|--ext-prefix-alias prefix][-x|--no-idata4] [-c|--no-idata5][--use-nul-prefixed-import-tables][-I|--identify library-file-name] [--identify-strict][-i|--interwork][-n|--nodelete] [-t|--temp-prefix prefix][-v|--verbose][-h|--help] [-V|--version][--no-leading-underscore] [--leading-underscore][--deterministic-libraries] [--non-deterministic-libraries][object-file ...]

dlltool reads its inputs, which can come from the -d and -b options as well as object
files specified on the command line. It then processes these inputs and if the -e option has
been specified it creates a exports file. If the -l option has been specified it creates a library
file and if the -z option has been specified it creates a def file. Any or all of the -e, -l and-z options can be present in one invocation of dlltool.
When creating a DLL, along with the source for the DLL, it is necessary to have threeother files. dlltool can help with the creation of these files.
The first file is a .def file which specifies which functions are exported from the DLL,
which functions the DLL imports, and so on. This is a text file and can be created by hand,or dlltool can be used to create it using the -z option. In this case dlltool will scan
the object files specified on its command line looking for those functions which have been
specially marked as being exported and put entries for them in the .def file it creates.
In order to mark a function as being exported from a DLL, it needs to have an-export:<name_of_function> entry in the ‘.drectve’ section of the object file. Thiscan be done in C by using the asm() operator:

Chapter 14: dlltool73

asm (".section .drectve");asm (".ascii \"-export:my_func\"");
int my_func (void) { ... }The second file needed for DLL creation is an exports file. This file is linked with theobject files that make up the body of the DLL and it handles the interface between the DLL
and the outside world. This is a binary file and it can be created by giving the -e option to
dlltool when it is creating or reading in a .def file.
The third file needed for DLL creation is the library file that programs will link with inorder to access the functions in the DLL (an ‘import library’). This file can be created bygiving the -l option to dlltool when it is creating or reading in a .def file.
If the -y option is specified, dlltool generates a delay-import library that can be usedinstead of the normal import library to allow a program to link to the dll only as soon as animported function is called for the first time. The resulting executable will need to be linked
to the static delayimp library containing delayLoadHelper2(), which in turn will import
LoadLibraryA and GetProcAddress from kernel32.
dlltool builds the library file by hand, but it builds the exports file by creating temporary
files containing assembler statements and then assembling these. The -S command-line
option can be used to specify the path to the assembler that dlltool will use, and the -f
option can be used to pass specific flags to that assembler. The -n can be used to prevent
dlltool from deleting these temporary assembler files when it is done, and if -n is specified
twice then this will prevent dlltool from deleting the temporary object files it used to build
the library.
Here is an example of creating a DLL from a source file ‘dll.c’ and also creating a
program (from an object file called ‘program.o’) that uses that DLL:
gcc -c dll.c
dlltool -e exports.o -l dll.lib dll.ogcc dll.o exports.o -o dll.dll
gcc program.o dll.lib -o program

dlltool may also be used to query an existing import library to determine the name of
the DLL to which it is associated. See the description of the -I or --identify option.
The command-line options have the following meanings:-d filename--input-def filename
Specifies the name of a .def file to be read in and processed.
-b filename--base-file filename
Specifies the name of a base file to be read in and processed. The contents ofthis file will be added to the relocation section in the exports file generated bydlltool.
-e filename--output-exp filename
Specifies the name of the export file to be created by dlltool.
-z filename--output-def filename
Specifies the name of the .def file to be created by dlltool.

Chapter 14: dlltool

74-l filename--output-lib filename
Specifies the name of the library file to be created by dlltool.
-y filename--output-delaylib filename
Specifies the name of the delay-import library file to be created by dlltool.
--deterministic-libraries--non-deterministic-libraries
When creating output libraries in response to either the --output-lib or--output-delaylib options either use the value of zero for any timestamps,
user ids and group ids created (--deterministic-libraries) or the actual
timestamps, user ids and group ids (--non-deterministic-libraries).
--export-all-symbols
Treat all global and weak defined symbols found in the input object files as
symbols to be exported. There is a small list of symbols which are not exported
by default; see the --no-default-excludes option. You may add to the list ofsymbols to not export by using the --exclude-symbols option.
--no-export-all-symbols
Only export symbols explicitly listed in an input .def file or in ‘.drectve’
sections in the input object files. This is the default behaviour. The ‘.drectve’
sections are created by ‘dllexport’ attributes in the source code.
--exclude-symbols list
Do not export the symbols in list. This is a list of symbol names separated bycomma or colon characters. The symbol names should not contain a leading
underscore. This is only meaningful when --export-all-symbols is used.
--no-default-excludes
When --export-all-symbols is used, it will by default avoid exporting certain
special symbols. The current list of symbols to avoid exporting is ‘DllMain@12’,‘DllEntryPoint@0’, ‘impure_ptr’. You may use the --no-default-excludes
option to go ahead and export these special symbols. This is only meaningfulwhen --export-all-symbols is used.
-S path--as path Specifies the path, including the filename, of the assembler to be used to create
the exports file.
-f options--as-flags options
Specifies any specific command-line options to be passed to the assembler whenbuilding the exports file. This option will work even if the -S option is not used.
This option only takes one argument, and if it occurs more than once on thecommand line, then later occurrences will override earlier occurrences. So if it
is necessary to pass multiple options to the assembler they should be enclosed
in double quotes.

Chapter 14: dlltool

75-D name--dll-name nameSpecifies the name to be stored in the .def file as the name of the DLL whenthe -e option is used. If this option is not present, then the filename given to
the -e option will be used as the name of the DLL.
-m machine-machine machine
Specifies the type of machine for which the library file should be built. dlltool
has a built in default type, depending upon how it was created, but this option
can be used to override that. This is normally only useful when creating DLLs
for an ARM processor, when the contents of the DLL are actually encode using
Thumb instructions.
-a--add-indirect
Specifies that when dlltool is creating the exports file it should add a section
which allows the exported functions to be referenced without using the importlibrary. Whatever the hell that means!
-U--add-underscore
Specifies that when dlltool is creating the exports file it should prepend anunderscore to the names of all exported symbols.
--no-leading-underscore--leading-underscore
Specifies whether standard symbol should be forced to be prefixed, or not.
--add-stdcall-underscore
Specifies that when dlltool is creating the exports file it should prepend
an underscore to the names of exported stdcall functions. Variable names
and non-stdcall function names are not modified. This option is useful whencreating GNU-compatible import libs for third party DLLs that were built with
MS-Windows tools.
-k--kill-at
Specifies that ‘@<number>’ suffixes should be omitted from the names of stdcall
functions that will be imported from the DLL. This is useful when creating animport library for a DLL which exports stdcall functions but without the usual‘@<number>’ symbol name suffix.
This does not change the naming of symbols provided by the import library
to programs linked against it, but only the entries in the import table (ie the.idata section).
-A--add-stdcall-alias
Specifies that when dlltool is creating the exports file it should add aliases
for stdcall symbols without ‘@ <number>’ in addition to the symbols with ‘@<number>’.

Chapter 14: dlltool

76-p--ext-prefix-alias prefix
Causes dlltool to create external aliases for all DLL imports with the specified
prefix. The aliases are created for both external and import symbols with noleading underscore.
-x--no-idata4
Specifies that when dlltool is creating the exports and library files it should
omit the .idata4 section. This is for compatibility with certain operating
systems.
--use-nul-prefixed-import-tablesSpecifies that when dlltool is creating the exports and library files it should
prefix the .idata4 and .idata5 by zero an element. This emulates old gnu
import library generation of dlltool. By default this option is turned off.
-c--no-idata5
Specifies that when dlltool is creating the exports and library files it should
omit the .idata5 section. This is for compatibility with certain operating
systems.
-I filename--identify filename
Specifies that dlltool should inspect the import library indicated by filename
and report, on stdout, the name(s) of the associated DLL(s). This can be
performed in addition to any other operations indicated by the other options
and arguments. dlltool fails if the import library does not exist or is not
actually an import library. See also --identify-strict.
--identify-strict
Modifies the behavior of the --identify option, such that an error is reported
if filename is associated with more than one DLL.
-i--interwork
Specifies that dlltool should mark the objects in the library file and exports
file that it produces as supporting interworking between ARM and Thumb code.
-n--nodelete
Makes dlltool preserve the temporary assembler files it used to create theexports file. If this option is repeated then dlltool will also preserve the temporary
object files it uses to create the library file.
-t prefix--temp-prefix prefix
Makes dlltool use prefix when constructing the names of temporary assembler
and object files. By default, the temp file prefix is generated from the pid.

Chapter 14: dlltool

77-v--verboseMake dlltool describe what it is doing.
-h--help

Displays a list of command-line options and then exits.

-V--version
Displays dlltool’s version number and then exits.

14.1 The format of the dlltool .def file
A .def file contains any number of the following commands:
NAME name [ , base ]The result is going to be named name.exe.
LIBRARY name [ , base ]The result is going to be named name.dll. Note: If you want to use LIBRARY
as name then you need to quote. Otherwise this will fail due a necessary hackfor libtool (see PR binutils/13710 for more details).
EXPORTS ( ( ( name1 [ = name2 ] ) | ( name1 = module-name . external-name ) ) [== its name ][ integer ] [ NONAME ] [ CONSTANT ] [ DATA ] [ PRIVATE ] ) *Declares name1 as an exported symbol from the DLL, with optional ordinal
number integer, or declares name1 as an alias (forward) of the function externalname in the DLL. If its name is specified, this name is used as string in exporttable. module-name. Note: The EXPORTS has to be the last command in .def
file, as keywords are treated - beside LIBRARY - as simple name-identifiers. If
you want to use LIBRARY as name then you need to quote it.
IMPORTS ( ( internal-name = module-name . integer ) | [ internal-name = ] module-name. external-name ) [ == ) its_name ] *Declares that external-name or the exported function whose ordinal number
is integer is to be imported from the file module-name. If internal-name isspecified then this is the name that the imported function will be referred toin the body of the DLL. If its name is specified, this name is used as string inimport table. Note: The IMPORTS has to be the last command in .def file, as
keywords are treated - beside LIBRARY - as simple name-identifiers. If you want
to use LIBRARY as name then you need to quote it.
DESCRIPTION string
Puts string into the output .exp file in the .rdata section.
STACKSIZE number-reserve [, number-commit ]HEAPSIZE number-reserve [, number-commit ]Generates --stack or --heap number-reserve,number-commit in the output.drectve section. The linker will see this and act upon it.

Chapter 14: dlltool

78

CODE attr +DATA attr +SECTIONS ( section-name attr + ) *Generates --attr section-name attr in the output .drectve section, where attr
is one of READ, WRITE, EXECUTE or SHARED. The linker will see this and act upon
it.

79

15 readelfreadelf [-a|--all][-h|--file-header][-l|--program-headers|--segments][-S|--section-headers|--sections][-g|--section-groups][-t|--section-details][-e|--headers][-s|--syms|--symbols][--dyn-syms|--lto-syms][--sym-base=[0|8|10|16]][--demangle=style|--no-demangle][--quiet][--recurse-limit|--no-recurse-limit][-U method|--unicode=method][-X|--extra-sym-info|--no-extra-sym-info][-n|--notes][-r|--relocs][-u|--unwind][-d|--dynamic][-V|--version-info][-A|--arch-specific][-D|--use-dynamic][-L|--lint|--enable-checks][-x <number or name>|--hex-dump=<number or name>][-p <number or name>|--string-dump=<number or name>][-R <number or name>|--relocated-dump=<number or name>][-z|--decompress][-c|--archive-index][-w[lLiaprmfFsoORtUuTgAck]|--debug-dump[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=framesinterp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr[-wK|--debug-dump=follow-links][-wN|--debug-dump=no-follow-links][-wD|--debug-dump=use-debuginfod][-wE|--debug-dump=do-not-use-debuginfod][-P|--process-links][--dwarf-depth=n][--dwarf-start=n][--ctf=section][--ctf-parent=section][--ctf-symbols=section][--ctf-strings=section][--sframe=section][-I|--histogram][-v|--version][-W|--wide][-T|--silent-truncation][-H|--help]
elffile...

readelf displays information about one or more ELF format object files. The options
control what particular information to display.
elffile . . . are the object files to be examined. 32-bit and 64-bit ELF files are supported,
as are archives containing ELF files.

Chapter 15: readelf

80

This program performs a similar function to objdump but it goes into more detail and it
exists independently of the bfd library, so if there is a bug in bfd then readelf will not beaffected.
The long and short forms of options, shown here as alternatives, are equivalent. At least
one option besides ‘-v’ or ‘-H’ must be given.
-a
--all

Equivalent to specifying --file-header, --program-headers, --sections,--symbols, --relocs, --dynamic, --notes, --version-info, --archspecific, --unwind, --section-groups and --histogram.
Note - this option does not enable --use-dynamic itself, so if that option is notpresent on the command line then dynamic symbols and dynamic relocs will
not be displayed.

-h--file-header
Displays the information contained in the ELF header at the start of the file.
-l--program-headers--segments
Displays the information contained in the file’s segment headers, if it has any.
Suppress "no symbols" diagnostic.

--quiet-S--sections--section-headers
Displays the information contained in the file’s section headers, if it has any.
-g--section-groups
Displays the information contained in the file’s section groups, if it has any.
-t--section-details
Displays the detailed section information. Implies -S.
-s--symbols--syms
Displays the entries in symbol table section of the file, if it has one. If a symbol
has version information associated with it then this is displayed as well. The
version string is displayed as a suffix to the symbol name, preceded by an @character. For example ‘foo@VER_1’. If the version is the default version to be
used when resolving unversioned references to the symbol then it is displayed asa suffix preceded by two @ characters. For example ‘foo@@VER_2’.
--dyn-syms
Displays the entries in dynamic symbol table section of the file, if it has one.
The output format is the same as the format used by the --syms option.
--lto-syms
Displays the contents of any LTO symbol tables in the file.

Chapter 15: readelf

81--sym-base=[0|8|10|16]
Forces the size field of the symbol table to use the given base. Any unrecognized
options will be treated as ‘0’. --sym-base=0 represents the default and legacy
behaviour. This will output sizes as decimal for numbers less than 100000. For
sizes 100000 and greater hexadecimal notation will be used with a 0x prefix.
--sym-base=8 will give the symbol sizes in octal. --sym-base=10 will always
give the symbol sizes in decimal. --sym-base=16 will always give the symbol
sizes in hexadecimal with a 0x prefix.
-C--demangle[=style]
Decode (demangle) low-level symbol names into user-level names. 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 Chapter 10 [c++filt], page 60, for more
information on demangling.
--no-demangle
Do not demangle low-level symbol names. This is the default.
--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 ofrecursion it is possible to create strings whose decoding will exhaust the amountof stack space available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion to 2048 levelsof nesting.
The default is for this limit to be enabled, but disabling it may be necessary inorder to demangle truly complicated names. Note however that if the recursion
limit is disabled then stack exhaustion is possible and any bug reports aboutsuch an event will be rejected.
-U [d|i|l|e|x|h]--unicode=[default|invalid|locale|escape|hex|highlight]
Controls the display of non-ASCII characters in identifier names. The default(--unicode=locale or --unicode=default) is to treat them as multibyte characters and display them in the current locale. All other versions of this option
treat the bytes as UTF-8 encoded values and attempt to interpret them. If theycannot be interpreted or if the --unicode=invalid option is used then they
are displayed as a sequence of hex bytes, encloses in curly parethesis characters.
Using the --unicode=escape option will display the characters as as unicode
escape sequences (\uxxxx). Using the --unicode=hex will display the charactersas hex byte sequences enclosed between angle brackets.
Using the --unicode=highlight will display the characters as unicode escapesequences but it will also highlighted them in red, assuming that colouring isChapter 15: readelf82

supported by the output device. The colouring is intended to draw attention to
the presence of unicode sequences when they might not be expected.
-X--extra-sym-info
When displaying details of symbols, include extra information not normallypresented. Currently this just adds the name of the section referenced by thesymbol’s index field, if there is one. In the future more information may bedisplayed when this option is enabled.
Enabling this option effectively enables the --wide option as well, at least whendisplaying symbol information.
--no-extra-sym-info
Disables the effect of the --extra-sym-info option. This is the default.
-e--headers
Display all the headers in the file. Equivalent to -h -l -S.
-n--notes

Displays the contents of the NOTE segments and/or sections, if any.

-r--relocs

Displays the contents of the file’s relocation section, if it has one.

-u--unwind

Displays the contents of the file’s unwind section, if it has one. Only the unwind
sections for IA64 ELF files, as well as ARM unwind tables (.ARM.exidx /.ARM.extab) are currently supported. If support is not yet implemented foryour architecture you could try dumping the contents of the .eh frames section
using the --debug-dump=frames or --debug-dump=frames-interp options.

-d--dynamic
Displays the contents of the file’s dynamic section, if it has one.
-V--version-info
Displays the contents of the version sections in the file, it they exist.
-A--arch-specific
Displays architecture-specific information in the file, if there is any.
-D--use-dynamic
When displaying symbols, this option makes readelf use the symbol hash tablesin the file’s dynamic section, rather than the symbol table sections.
When displaying relocations, this option makes readelf display the dynamic
relocations rather than the static relocations.

Chapter 15: readelf83-L--lint--enable-checks
Displays warning messages about possible problems with the file(s) being examined. If used on its own then all of the contents of the file(s) will be examined.
If used with one of the dumping options then the warning messages will only be
produced for the things being displayed.
-x <number or name>--hex-dump=<number or name>
Displays the contents of the indicated section as a hexadecimal bytes. A number
identifies a particular section by index in the section table; any other string
identifies all sections with that name in the object file.
-R <number or name>--relocated-dump=<number or name>
Displays the contents of the indicated section as a hexadecimal bytes. A number
identifies a particular section by index in the section table; any other string
identifies all sections with that name in the object file. The contents of thesection will be relocated before they are displayed.
-p <number or name>--string-dump=<number or name>
Displays the contents of the indicated section as printable strings. A number
identifies a particular section by index in the section table; any other string
identifies all sections with that name in the object file.
-z--decompress
Requests that the section(s) being dumped by x, R or p options are decompressed
before being displayed. If the section(s) are not compressed then they aredisplayed as is.
-c--archive-index
Displays the file symbol index information contained in the header part of binary
archives. Performs the same function as the t command to ar, but without
using the BFD library. See Chapter 1 [ar], page 1.
-w[lLiaprmfFsOoRtUuTgAckK]--debugdump[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=framesinterp,=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 are automatically decompressed (temporarily) before
they are displayed. If one or more of the optional letters or words follows theswitch then only those type(s) of data will be dumped. The letters and words
refer to the following information:

Chapter 15: readelf84a=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‘.debug_tu_index’ sections.
f=framesthe‘.debug_cu_index’

and/or

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

k
=links

Displays the contents of the ‘.debug_info’ section. Note: theoutput from this option can also be restricted by the use of the--dwarf-depth and --dwarf-start options.
Displaysthecontentsofthe‘.gnu_debuglink’,‘.gnu_debugaltlink’ and ‘.debug_sup’ sections, if any ofthem are present. Also displays any links to separate dwarf object
files (dwo), if they are 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 foundin linked, separate debug info file(s). This can result in multiple
versions of the same debug section being displayed if it exists inmore than one file.
In addition, when displaying DWARF attributes, if a form is foundthat 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 chosenwhen configuring the binutils via the --enable-follow-debuglinks=yes or --enable-follow-debug-links=no options. If these
are not used then the default is to enable the following of debug
links.

Chapter 15: readelf85

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 toresolve. This behaviour can be disabled via the =do-not-usedebuginfod 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 is a need to follow
debug links. This is the default behaviour.
E=do-not-use-debuginfod
Disables contacting debuginfod servers when there is 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=macroo=loc

Displays the contents‘.debug_macinfo’ sections.

of

the

Displaysthecontents‘.debug_loclists’ sections.

of

the

‘.debug_macro’

and/or‘.debug_loc’

and/orO=str-offsets
Displays the contents of the ‘.debug_str_offsets’ section.
p=pubnames
Displays the contents of the‘.debug_gnu_pubnames’ sections.
r=aranges
R=Ranges‘.debug_pubnames’

and/or

Displays the contents of the ‘.debug_aranges’ section.
Displays the contents of‘.debug_rnglists’ sections.

the‘.debug_ranges’

and/orChapter 15: readelf

s
=str
t
=pubtype86

Displays the contents of the ‘.debug_str’, ‘.debug_line_str’
and/or ‘.debug_str_offsets’ sections.
Displays the contents of the‘.debug_gnu_pubtypes’ sections.

‘.debug_pubtypes’

and/orT=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.
--dwarf-depth=nLimit the dump of the .debug_info section to n children. This is only usefulwith --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=nPrint 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.
-P--process-links
Display the contents of non-debug sections found in separate debuginfo files thatare linked to the main file. This option automatically implies the -wK option,and only sections requested by other command line options will be displayed.
--ctf[=section]
Display the contents of the specified CTF section. CTF sections themselvescontain many subsections, all of which are displayed in order.
By default, display the name of the section named .ctf, which is the nameemitted by ld.
--ctf-parent=member
If the CTF section contains ambiguously-defined types, it will consist of anarchive of many CTF dictionaries, all inheriting from one dictionary containingChapter 15: readelf87

unambiguous types. This member is by default named .ctf, like the section
containing it, but it is possible to change this name using the ctf_link_set_
memb_name_changer function at link time. When looking at CTF archives thathave 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 theparent.
--ctf-symbols=section--ctf-strings=section
Specify the name of another section from which the CTF file can inherit stringsand symbols. By default, the .symtab and its linked string table are used.
If either of --ctf-symbols or --ctf-strings is specified, the other must be
specified as well.
-I--histogram
Display a histogram of bucket list lengths when displaying the contents of thesymbol tables.
-v--version
Display the version number of readelf.
-W--wideDon’t break output lines to fit into 80 columns. By default readelf breaks
section header and segment listing lines for 64-bit ELF files, so that they fit into
80 columns. This option causes readelf to print each section header resp. eachsegment one a single line, which is far more readable on terminals wider than
80 columns.

-T--silent-truncation
Normally when readelf is displaying a symbol name, and it has to truncate thename to fit into an 80 column display, it will add a suffix of [...] to the name.
This command line option disables this behaviour, allowing 5 more charactersof the name to be displayed and restoring the old behaviour of readelf (prior torelease 2.35).
-H--help

Display the command-line options understood by readelf.

88

16 elfedit
elfedit [--input-mach=machine][--input-type=type][--input-osabi=osabi][--input-abiversion=version]--output-mach=machine--output-type=type--output-osabi=osabi--output-abiversion=version--enable-x86-feature=feature--disable-x86-feature=feature[-v|--version][-h|--help]
elffile...

elfedit updates the ELF header and program property of ELF files which have thematching ELF machine and file types. The options control how and which fields in the ELF
header and program property should be updated.
elffile . . . are the ELF files to be updated. 32-bit and 64-bit ELF files are supported, as
are archives containing ELF files.
The long and short forms of options, shown here as alternatives, are equivalent. At
least one of the --output-mach, --output-type, --output-osabi, --output-abiversion,--enable-x86-feature and --disable-x86-feature options must be given.
--input-mach=machine
Set the matching input ELF machine type to machine. If --input-mach isn’t
specified, it will match any ELF machine types.
The supported ELF machine types are, i386, IAMCU, L1OM, K1OM andx86-64.
--output-mach=machine
Change the ELF machine type in the ELF header to machine. The supported
ELF machine types are the same as --input-mach.
--input-type=type
Set the matching input ELF file type to type. If --input-type isn’t specified,
it will match any ELF file types.
The supported ELF file types are, rel, exec and dyn.
--output-type=type
Change the ELF file type in the ELF header to type. The supported ELF types
are the same as --input-type.
--input-osabi=osabi
Set the matching input ELF file OSABI to osabi. If --input-osabi isn’t
specified, it will match any ELF OSABIs.
The supported ELF OSABIs are, none, HPUX, NetBSD, GNU, Linux (alias forGNU ), Solaris, AIX, Irix, FreeBSD, TRU64, Modesto, OpenBSD, OpenVMS,
NSK, AROS and FenixOS.
--output-osabi=osabi
Change the ELF OSABI in the ELF header to osabi. The supported ELF
OSABI are the same as --input-osabi.

Chapter 16: elfedit

89--input-abiversion=version
Set the matching input ELF file ABIVERSION to version. version must be
between 0 and 255. If --input-abiversion isn’t specified, it will match any
ELF ABIVERSIONs.
--output-abiversion=version
Change the ELF ABIVERSION in the ELF header to version. version must be
between 0 and 255.
--enable-x86-feature=feature
Set the feature bit in program property in exec or dyn ELF files with machinetypes of i386 or x86-64. The supported features are, ibt, shstk, lam u48 andlam u57.
--disable-x86-feature=feature
Clear the feature bit in program property in exec or dyn ELF files with machinetypes of i386 or x86-64. The supported features are the same as --enablex86-feature.
Note: --enable-x86-feature and --disable-x86-feature are available only
on hosts with ‘mmap’ support.
-v--version
Display the version number of elfedit.
-h--help

Display the command-line options understood by elfedit.

90

17 Common Options
The following command-line options are supported by all of the programs described in thismanual.
@file

Read command-line options from file. The options read are inserted in placeof the original @file option. If file does not exist, or cannot be read, then theoption 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 thecharacter to be included with a backslash. The file may itself contain additional@file options; any such options will be processed recursively.

--help

Display the command-line options supported by the program.

--version
Display the version number of the program.

91

18 Selecting the Target System
You can specify two aspects of the target system to the gnu binary file utilities, each inseveral ways:• the target• the architecture
In the following summaries, the lists of ways to specify values are in order of decreasing
precedence. The ways listed first override those listed later.
The commands to list valid values only list the values for which the programs you
are running were configured. If they were configured with --enable-targets=all, thecommands list most of the available values, but a few are left out; not all targets can be
configured in at once because some of them can only be configured native (on hosts withthe same type as the target system).

18.1 Target Selection
A target is an object file format. A given target may be supported for multiple architectures(see Section 18.2 [Architecture Selection], page 92). A target selection may also havevariations for different operating systems or architectures.
The command to list valid target values is ‘objdump -i’ (the first column of output
contains the relevant information).
Some sample values are: ‘a.out-hp300bsd’, ‘ecoff-littlemips’, ‘a.out-sunos-big’.
You can also specify a target using a configuration triplet. This is the same sort of namethat is passed to configure to specify a target. When you use a configuration triplet as anargument, it must be fully canonicalized. You can see the canonical version of a triplet byrunning the shell script config.sub which is included with the sources.
Some sample configuration‘sparc-sun-sunos’.

tripletsare:‘m68k-hp-bsd’,

objdump Target
Ways to specify:
1. command-line option: -b or --target
2. environment variable GNUTARGET
3. deduced from the input file

objcopy and strip Input Target
Ways to specify:
1. command-line options: -I or --input-target, or -F or --target
2. environment variable GNUTARGET
3. deduced from the input file‘mips-dec-ultrix’,Chapter 18: Selecting the Target System92

objcopy and strip Output Target
Ways to specify:
1. command-line options: -O or --output-target, or -F or --target
2. the input target (see “objcopy and strip Input Target” above)
3. environment variable GNUTARGET
4. deduced from the input file

nm, size, and strings Target
Ways to specify:
1. command-line option: --target
2. environment variable GNUTARGET
3. deduced from the input file18.2 Architecture Selection
An architecture is a type of cpu on which an object file is to run. Its name may contain acolon, separating the name of the processor family from the name of the particular cpu.
The command to list valid architecture values is ‘objdump -i’ (the second column contains
the relevant information).
Sample values: ‘m68k:68020’, ‘mips:3000’, ‘sparc’.

objdump Architecture
Ways to specify:
1. command-line option: -m or --architecture
2. deduced from the input file

objcopy, nm, size, strings Architecture
Ways to specify:
1. deduced from the input file93

19 debuginfod
debuginfod is a web service that indexes ELF/DWARF debugging resources by build-id and serves them over HTTP. For more information see:https://sourceware.org/elfutils/Debuginfod.html
Binutils can be built with the debuginfod client library libdebuginfod using the --withdebuginfod configure option. This option is enabled by default if libdebuginfod is installed
and found at configure time. This allows objdump and readelf to automatically query
debuginfod servers for separate debug files when the files are otherwise not found.
debuginfod is packaged with elfutils, starting with version 0.178. You can get the latest
version from ‘https://sourceware.org/elfutils/’.
The DWARF info dumping tools (readelf and objdump) have options to control when
they should access the debuginfod servers. By default this access is enabled.

94

20 Reporting Bugs
Your bug reports play an essential role in making the binary utilities reliable.
Reporting a bug may help you by bringing a solution to your problem, or it may not. But
in any case the principal function of a bug report is to help the entire community by making
the next version of the binary utilities work better. Bug reports are your contribution totheir maintenance.
In order for a bug report to serve its purpose, you must include the information thatenables us to fix the bug.

20.1 Have You Found a Bug?
If you are not sure whether you have found a bug, here are some guidelines:• If a binary utility gets a fatal signal, for any input whatever, that is a bug. Reliableutilities never crash.
• If a binary utility produces an error message for valid input, that is a bug.
• If you are an experienced user of binary utilities, your suggestions for improvement are
welcome in any case.

20.2 How to Report Bugs
A number of companies and individuals offer support for gnu products. If you obtained thebinary utilities from a support organization, we recommend you contact that organization
first.
You can find contact information for many support companies and individuals in the file
etc/SERVICE in the gnu Emacs distribution.
In any event, we also recommend that you send bug reports for the binary utilities tohttps://sourceware.org/bugzilla/.
The fundamental principle of reporting bugs usefully is this: report all the facts. If you
are not sure whether to state a fact or leave it out, state it!
Often people omit facts because they think they know what causes the problem andassume that some details do not matter. Thus, you might assume that the name of a file
you use in an example does not matter. Well, probably it does not, but one cannot be sure.
Perhaps the bug is a stray memory reference which happens to fetch from the location wherethat pathname is stored in memory; perhaps, if the pathname were different, the contents ofthat location would fool the utility into doing the right thing despite the bug. Play it safeand give a specific, complete example. That is the easiest thing for you to do, and the mosthelpful.
Keep in mind that the purpose of a bug report is to enable us to fix the bug if it is new
to us. Therefore, always write your bug reports on the assumption that the bug has notbeen reported previously.
Sometimes people give a few sketchy facts and ask, “Does this ring a bell?” This cannot
help us fix a bug, so it is basically useless. We respond by asking for enough details toenable us to investigate. You might as well expedite matters by sending them to begin with.

Chapter 20: Reporting Bugs

95

To enable us to fix the bug, you should include all these things:• The version of the utility. Each utility announces it if you start it with the --version
argument.
Without this, we will not know whether there is any point in looking for the bug in thecurrent version of the binary utilities.
• Any patches you may have applied to the source, including any patches made to the
BFD library.
• The type of machine you are using, and the operating system name and version number.
• What compiler (and its version) was used to compile the utilities—e.g. “gcc-2.7”.
• The command arguments you gave the utility to observe the bug. To guarantee you
will not omit something important, list them all. A copy of the Makefile (or the output
from make) is sufficient.
If we were to try to guess the arguments, we would probably guess wrong and then wemight not encounter the bug.
• A complete input file, or set of input files, that will reproduce the bug. If the utility isreading an object file or files, then it is generally most helpful to send the actual object
files.
If the source files were produced exclusively using gnu programs (e.g., gcc, gas, and/or
the gnu ld), then it may be OK to send the source files rather than the object files. In
this case, be sure to say exactly what version of gcc, or whatever, was used to produce
the object files. Also say how gcc, or whatever, was configured.
• A description of what behavior you observe that you believe is incorrect. For example,“It gets a fatal signal.”
Of course, if the bug is that the utility gets a fatal signal, then we will certainly noticeit. But if the bug is incorrect output, we might not notice unless it is glaringly wrong.
You might as well not give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should still say so explicitly.
Suppose something strange is going on, such as your copy of the utility is out of sync,
or you have encountered a bug in the C library on your system. (This has happened!)
Your copy might crash and ours would not. If you told us to expect a crash, then whenours fails to crash, we would know that the bug was not happening for us. If you had
not told us to expect a crash, then we would not be able to draw any conclusion fromour observations.
• If you wish to suggest changes to the source, send us context diffs, as generated by diffwith the -u, -c, or -p option. Always send diffs from the old file to the new file. If you
wish to discuss something in the ld source, refer to it by context, not by line number.
The line numbers in our development sources will not match those in your sources. Yourline numbers would convey no useful information to us.
Here are some things that are not necessary:• A description of the envelope of the bug.
Often people who encounter a bug spend a lot of time investigating which changes tothe input file will make the bug go away and which changes will not affect it.

Chapter 20: Reporting Bugs

96

This is often time consuming and not very useful, because the way we will find the bug is
by running a single example under the debugger with breakpoints, not by pure deduction
from a series of examples. We recommend that you save your time for something else.
Of course, if you can find a simpler example to report instead of the original one, thatis a convenience for us. Errors in the output will be easier to spot, running under the
debugger will take less time, and so on.
However, simplification is not vital; if you do not want to do this, report the bug anyway
and send us the entire test case you used.
• A patch for the bug.
A patch for the bug does help us if it is a good one. But do not omit the necessary
information, such as the test case, on the assumption that a patch is all we need. We
might see problems with your patch and decide to fix the problem another way, or wemight not understand it at all.
Sometimes with programs as complicated as the binary utilities it is very hard toconstruct an example that will make the program follow a certain path through thecode. If you do not send us the example, we will not be able to construct one, so wewill not be able to verify that the bug is fixed.
And if we cannot understand what bug you are trying to fix, or why your patch should
be an improvement, we will not install it. A test case will help us to understand.
• A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even we cannot guess right about such things without
first using the debugger to find the facts.

97

Appendix A GNU Free Documentation License
Version 1.3, 3 November 2008c
Copyright
2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
http://fsf.org/
Everyone is permitted to copy and distribute verbatim copiesof this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other functional anduseful document free in the sense of freedom: to assure everyone the effective freedom
to copy and redistribute it, with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible for modifications
made by others.
This License is a kind of “copyleft”, which means that derivative works of the document
must themselves be free in the same sense. It complements the GNU General Public
License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because
free software needs free documentation: a free program should come with manuals
providing the same freedoms that the software does. But this License is not limited tosoftware manuals; it can be used for any textual work, regardless of subject matter orwhether it is published as a printed book. We recommend this License principally forworks whose purpose is instruction or reference.
1. APPLICABILITY AND DEFINITIONSThis License applies to any manual or other work, in any medium, that contains a noticeplaced by the copyright holder saying it can be distributed under the terms of thisLicense. Such a notice grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The “Document”, below, refers
to any such manual or work. Any member of the public is a licensee, and is addressed
as “you”. You accept the license if you copy, modify or distribute the work in a way
requiring permission under copyright law.
A “Modified Version” of the Document means any work containing the Document or
a portion of it, either copied verbatim, or with modifications and/or translated intoanother language.
A “Secondary Section” is a named appendix or a front-matter section of the Documentthat deals exclusively with the relationship of the publishers or authors of the Document
to the Document’s overall subject (or to related matters) and contains nothing that
could fall directly within that overall subject. (Thus, if the Document is in part a
textbook of mathematics, a Secondary Section may not explain any mathematics.) The
relationship could be a matter of historical connection with the subject or with related
matters, or of legal, commercial, philosophical, ethical or political position regardingthem.
The “Invariant Sections” are certain Secondary Sections whose titles are designated, as
being those of Invariant Sections, in the notice that says that the Document is released

Appendix A: GNU Free Documentation License98

under this License. If a section does not fit the above definition of Secondary then it is
not allowed to be designated as Invariant. The Document may contain zero Invariant
Sections. If the Document does not identify any Invariant Sections then there are none.
The “Cover Texts” are certain short passages of text that are listed, as Front-CoverTexts or Back-Cover Texts, in the notice that says that the Document is released under
this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
A “Transparent” copy of the Document means a machine-readable copy, represented in aformat whose specification is available to the general public, that is suitable for revising
the document straightforwardly with generic text editors or (for images composed ofpixels) generic paint programs or (for drawings) some widely available drawing editor,
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Transparent file format whose markup, or absence of markup, has been arranged tothwart or discourage subsequent modification by readers is not Transparent. An image
format is not Transparent if used for any substantial amount of text. A copy that is
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Examples of suitable formats for Transparent copies include plain ascii without markup,
Texinfo input format, LaTEX input format, SGML or XML using a publicly available
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Opaque formats include proprietary formats that can be read and edited only by
proprietary word processors, SGML or XML for which the DTD and/or processing
tools are not generally available, and the machine-generated HTML, PostScript or PDF
produced by some word processors for output purposes only.
The “Title Page” means, for a printed book, the title page itself, plus such following
pages as are needed to hold, legibly, the material this License requires to appear in thetitle page. For works in formats which do not have any title page as such, “Title Page”
means the text near the most prominent appearance of the work’s title, preceding the
beginning of the body of the text.
The “publisher” means any person or entity that distributes copies of the Document to
the public.
A section “Entitled XYZ” means a named subunit of the Document whose title either
is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in
another language. (Here XYZ stands for a specific section name mentioned below, suchas “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve
the Title” of such a section when you modify the Document means that it remains asection “Entitled XYZ” according to this definition.
The Document may include Warranty Disclaimers next to the notice which states that
this License applies to the Document. These Warranty Disclaimers are considered to be
included by reference in this License, but only as regards disclaiming warranties: anyother implication that these Warranty Disclaimers may have is void and has no effecton the meaning of this License.
2. VERBATIM COPYING

Appendix A: GNU Free Documentation License

99

You may copy and distribute the Document in any medium, either commercially or
noncommercially, provided that this License, the copyright notices, and the license
notice saying this License applies to the Document are reproduced in all copies, andthat you add no other conditions whatsoever to those of this License. You may not use
technical measures to obstruct or control the reading or further copying of the copies
you make or distribute. However, you may accept compensation in exchange for copies.
If you distribute a large enough number of copies you must also follow the conditions in
section 3.
You may also lend copies, under the same conditions stated above, and you may publicly
display copies.
3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly have printed covers) of
the Document, numbering more than 100, and the Document’s license notice requires
Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, allthese Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover. Both covers must also clearly and legibly identify you as the publisherof these copies. The front cover must present the full title with all words of the title
equally prominent and visible. You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve the title of theDocument and satisfy these conditions, can be treated as verbatim copying in otherrespects.
If the required texts for either cover are too voluminous to fit legibly, you should put
the first ones listed (as many as fit reasonably) on the actual cover, and continue therest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100,
you must either include a machine-readable Transparent copy along with each Opaquecopy, or state in or with each Opaque copy a computer-network location from which
the general network-using public has access to download using public-standard network
protocols a complete Transparent copy of the Document, free of added material. If
you use the latter option, you must take reasonably prudent steps, when you begin
distribution of Opaque copies in quantity, to ensure that this Transparent copy willremain thus accessible at the stated location until at least one year after the last time
you distribute an Opaque copy (directly or through your agents or retailers) of that
edition to the public.
It is requested, but not required, that you contact the authors of the Document wellbefore redistributing any large number of copies, to give them a chance to provide youwith an updated version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document under the conditionsof sections 2 and 3 above, provided that you release the Modified Version under precisely
this License, with the Modified Version filling the role of the Document, thus licensing
distribution and modification of the Modified Version to whoever possesses a copy of it.
In addition, you must do these things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title distinct from that of theDocument, and from those of previous versions (which should, if there were any,Appendix A: GNU Free Documentation License

100

be listed in the History section of the Document). You may use the same title as aprevious version if the original publisher of that version gives permission.
B. List on the Title Page, as authors, one or more persons or entities responsible forauthorship of the modifications in the Modified Version, together with at least fiveof the principal authors of the Document (all of its principal authors, if it has fewer
than five), unless they release you from this requirement.
C. State on the Title page the name of the publisher of the Modified Version, as the
publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications adjacent to the othercopyright notices.
F. Include, immediately after the copyright notices, a license notice giving the public
permission to use the Modified Version under the terms of this License, in the formshown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections and required CoverTexts given in the Document’s license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled “History”, Preserve its Title, and add to it an item
stating at least the title, year, new authors, and publisher of the Modified Version as
given on the Title Page. If there is no section Entitled “History” in the Document,
create one stating the title, year, authors, and publisher of the Document as given
on its Title Page, then add an item describing the Modified Version as stated in
the previous sentence.
J. Preserve the network location, if any, given in the Document for public access toa Transparent copy of the Document, and likewise the network locations given in
the Document for previous versions it was based on. These may be placed in the“History” section. You may omit a network location for a work that was publishedat least four years before the Document itself, or if the original publisher of theversion it refers to gives permission.
K. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Titleof the section, and preserve in the section all the substance and tone of each of thecontributor acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document, unaltered in their text andin their titles. Section numbers or the equivalent are not considered part of thesection titles.
M. Delete any section Entitled “Endorsements”. Such a section may not be includedin the Modified Version.
N. Do not retitle any existing section to be Entitled “Endorsements” or to conflict intitle with any Invariant Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or appendices that qualify as
Secondary Sections and contain no material copied from the Document, you may atyour option designate some or all of these sections as invariant. To do this, add theirAppendix A: GNU Free Documentation License

101

titles to the list of Invariant Sections in the Modified Version’s license notice. These
titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but
endorsements of your Modified Version by various parties—for example, statements ofpeer review or that the text has been approved by an organization as the authoritative
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up
to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified
Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be
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made by the same entity you are acting on behalf of, you may not add another; but
you may replace the old one, on explicit permission from the previous publisher that
added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission
to use their names for publicity for or to assert or imply endorsement of any Modified
Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under this License,
under the terms defined in section 4 above for modified versions, provided that you
include in the combination all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your combined work in its license
notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identicalInvariant Sections may be replaced with a single copy. If there are multiple Invariant
Sections with the same name but different contents, make the title of each such section
unique by adding at the end of it, in parentheses, the name of the original author or
publisher of that section if known, or else a unique number. Make the same adjustment
to the section titles in the list of Invariant Sections in the license notice of the combinedwork.
In the combination, you must combine any sections Entitled “History” in the various
original documents, forming one section Entitled “History”; likewise combine any
sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You
must delete all sections Entitled “Endorsements.”
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other documents released
under this License, and replace the individual copies of this License in the various
documents with a single copy that is included in the collection, provided that you follow
the rules of this License for verbatim copying of each of the documents in all otherrespects.
You may extract a single document from such a collection, and distribute it individually
under this License, provided you insert a copy of this License into the extracted
document, and follow this License in all other respects regarding verbatim copying ofthat document.

Appendix A: GNU Free Documentation License

102

7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other separate and independent
documents or works, in or on a volume of a storage or distribution medium, is called an“aggregate” if the copyright resulting from the compilation is not used to limit the legal
rights of the compilation’s users beyond what the individual works permit. When theDocument is included in an aggregate, this License does not apply to the other works
in the aggregate which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the Document,
then if the Document is less than one half of the entire aggregate, the Document’s CoverTexts may be placed on covers that bracket the Document within the aggregate, or theelectronic equivalent of covers if the Document is in electronic form. Otherwise theymust appear on printed covers that bracket the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may distribute translationsof the Document under the terms of section 4. Replacing Invariant Sections withtranslations requires special permission from their copyright holders, but you may
include translations of some or all Invariant Sections in addition to the original versionsof these Invariant Sections. You may include a translation of this License, and all thelicense notices in the Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the original versions of those
notices and disclaimers. In case of a disagreement between the translation and theoriginal version of this License or a notice or disclaimer, the original version will prevail.
If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically requirechanging the actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document except as expressly
provided under this License. Any attempt otherwise to copy, modify, sublicense, or
distribute it is void, and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license from a particular
copyright holder is reinstated (a) provisionally, unless and until the copyright holder
explicitly and finally terminates your license, and (b) permanently, if the copyrightholder fails to notify you of the violation by some reasonable means prior to 60 days
after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if
the copyright holder notifies you of the violation by some reasonable means, this is thefirst time you have received notice of violation of this License (for any work) from thatcopyright holder, and you cure the violation prior to 30 days after your receipt of thenotice.
Termination of your rights under this section does not terminate the licenses of parties
who have received copies or rights from you under this License. If your rights have been
terminated and not permanently reinstated, receipt of a copy of some or all of the samematerial does not give you any rights to use it.

Appendix A: GNU Free Documentation License

103

10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of the GNU Free
Documentation License from time to time. Such new versions will be similar in spirit
to the present version, but may differ in detail to address new problems or concerns.
See http://www.gnu.org/copyleft/.
Each version of the License is given a distinguishing version number. If the Document
specifies that a particular numbered version of this License “or any later version” applies
to it, you have the option of following the terms and conditions either of that specified
version or of any later version that has been published (not as a draft) by the Free
Software Foundation. If the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the Free Software
Foundation. If the Document specifies that a proxy can decide which future versionsof this License can be used, that proxy’s public statement of acceptance of a version
permanently authorizes you to choose that version for the Document.
11. RELICENSING“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide
Web server that publishes copyrightable works and also provides prominent facilities foranybody to edit those works. A public wiki that anybody can edit is an example ofsuch a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in thesite means any set of copyrightable works thus published on the MMC site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license publishedby Creative Commons Corporation, a not-for-profit corporation with a principal placeof business in San Francisco, California, as well as future copyleft versions of that license
published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or in part, as part ofanother Document.
An MMC is “eligible for relicensing” if it is licensed under this License, and if all works
that were first published under this License somewhere other than this MMC, andsubsequently incorporated in whole or in part into the MMC, (1) had no cover texts orinvariant sections, and (2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site under
CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is
eligible for relicensing.

Appendix A: GNU Free Documentation License

104

ADDENDUM: How to use this License for your documents
To use this License in a document you have written, include a copy of the License in the
document and put the following copyright and license notices just after the title page:
Copyright (C) year your name.
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, no Front-Cover Texts, and no Back-CoverTexts. A copy of the license is included in the section entitled ‘‘GNUFree Documentation License’’.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the“with. . . Texts.” line with this:with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.

If you have Invariant Sections without Cover Texts, or some other combination of thethree, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasingthese examples in parallel under your choice of free software license, such as the GNU
General Public License, to permit their use in free software.

105

Binutils Index–D–enable-deterministic-archives . . . . . . 4, 5, 23, 49, 57

dates in archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
debug symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
debugging symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
deleting from archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
demangling C++ symbols . . . . . . . . . . . . . . . . . . . . . . . 60
demangling in nm . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 81
demangling in objdump . . . . . . . . . . . . . . . . . . . . 34, 64
deterministic archives . . . . . . . . . . . . . . 4, 5, 23, 49, 57
disassembling object code . . . . . . . . . . . . . . . . . . . . . . 35
disassembly architecture . . . . . . . . . . . . . . . . . . . . . . . 37
disassembly endianness . . . . . . . . . . . . . . . . . . . . . . . . . 36
disassembly, with source . . . . . . . . . . . . . . . . . . . . . . . 41
discarding symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
dlltool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
DLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
dynamic relocation entries, in object file . . . . . . . . 41
dynamic symbol table entries, printing . . . . . . . . . 47
dynamic symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.
.stab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

A
Add prefix to absolute paths . . . . . . . . . . . . . . . . . . . 42
addr2line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
address to file name and line number . . . . . . . . . . . 63
all header information, object file. . . . . . . . . . . . . . . 48
ar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
ar compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
architectures available. . . . . . . . . . . . . . . . . . . . . . . . . . 37
archive contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Archive file symbol index information . . . . . . . . . . 83
archive headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
archives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Bbase files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
bug criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
bug reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
bugs, reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

C
c++filt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
changing object addresses . . . . . . . . . . . . . . . . . . . . . . 23changing section address . . . . . . . . . . . . . . . . . . . . . . . 24
changing section LMA . . . . . . . . . . . . . . . . . . . . . . . . . 24
changing section VMA . . . . . . . . . . . . . . . . . . . . . . . . . 24
changing start address . . . . . . . . . . . . . . . . . . . . . . . . . 23
collections of files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Compact Type Format . . . . . . . . . . . . . . . . . . . . . 45, 86
compatibility, ar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
compressed section contents . . . . . . . . . . . . . . . . . . . . 48
contents of archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
creating archives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
creating thin archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
CTF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45, 86
cxxfilt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

E
ELF dynamic section information . . . . . . . . . . . . . . 82
ELF dynamic symbol table information . . . . . . . . 80
ELF file header information . . . . . . . . . . . . . . . . . . . . 80
ELF file information . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
ELF notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
ELF object file format . . . . . . . . . . . . . . . . . . . . . . . . . 46
ELF program header information. . . . . . . . . . . . . . . 80
ELF reloc information . . . . . . . . . . . . . . . . . . . . . . . . . 82
ELF section group information . . . . . . . . . . . . . . . . . 80
ELF section information . . . . . . . . . . . . . . . . . . . . . . . 80
ELF segment information . . . . . . . . . . . . . . . . . . . . . . 80
ELF symbol table information . . . . . . . . . . . . . . . . . 80
ELF version sections information . . . . . . . . . . . . . . . 82
elfedit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
endianness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
error on valid input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
external symbols . . . . . . . . . . . . . . . . . . . . . . . . 13, 14, 15
extract from archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Ffatal signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
file name. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

H
header information, all . . . . . . . . . . . . . . . . . . . . . . . . . 48

Binutils Index

106

I

R

input .def file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
input file name. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Instruction width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

radix for section sizes . . . . . . . . . . . . . . . . . . . . . . . . . . 51
ranlib . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 49
readelf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
relative placement in archive . . . . . . . . . . . . . . . . . . . . 3
relocation entries, in object file . . . . . . . . . . . . . . . . . 41
removing symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
repeated names in archive . . . . . . . . . . . . . . . . . . . . . . . 3
replacement in archive . . . . . . . . . . . . . . . . . . . . . . . . . . 2reporting bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

L
ld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
linker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
listings strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
LTO symbol table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Mmachine instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
moving in archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
MRI compatibility, ar . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Nname duplication in archive . . . . . . . . . . . . . . . . . . . . . 3
name length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
nm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
nm compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 13
nm format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 13
not writing archive index . . . . . . . . . . . . . . . . . . . . . . . . 4

Oobjdump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
objdump inlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
object code format . . . . . . . . . . . . . . 16, 34, 51, 53, 64
object file header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
object file information. . . . . . . . . . . . . . . . . . . . . . . . . . 33
object file offsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
object file sections . . . . . . . . . . . . . . . . . . . . . . . . . . 41, 48
object formats available . . . . . . . . . . . . . . . . . . . . . . . . 37
offsets of files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
operations on archive . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Pplugins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 15
printing from archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
printing strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Sscripts, ar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
section addresses in objdump. . . . . . . . . . . . . . . . . . . 34
section headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
section information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
section sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
sections, full contents . . . . . . . . . . . . . . . . . . . . . . . 41, 48
separate debug files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
SFrame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
size display format . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
size number format . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
sorting symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
source code context . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
source disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
source file name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
source filenames for object files . . . . . . . . . . . . . . . . . 37
stab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
start-address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
stop-address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
strings, printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
strip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Strip absolute paths . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
symbol index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 49
symbol index, listing . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
symbol line numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
symbol table entries, printing . . . . . . . . . . . . . . . . . . 46
symbol table size base. . . . . . . . . . . . . . . . . . . . . . . . . . 81
symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
symbols, discarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Tthin archives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

UQquick append to archive . . . . . . . . . . . . . . . . . . . . . . . . . 2
quiet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

undefined symbols . . . . . . . . . . . . . . . . . . . . . . . . . . 14, 15
Unix compatibility, ar. . . . . . . . . . . . . . . . . . . . . . . . . . . 2
unwind information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Update ELF header . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
updating an archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Binutils Index

107

V

W

VMA in objdump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

wide output, printing . . . . . . . . . . . . . . . . . . . . . . . . . . 48
writing archive index . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4