path: root/ld/ld.1

.\" Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 1999, 2000 Free Software Foundation
.\" See section COPYING for conditions for redistribution
.TH ld 1 "" "Free Software Foundation" "GNU Development Tools"
.de BP
.sp
.ti \-.2i
\(**
..

.SH NAME
ld \- the GNU linker

.SH SYNOPSIS
.hy 0
.na
.TP
.B ld 
.RB "[\|" \-o "
.I output\c
\&\|] \c
.I objfile\c
\&.\|.\|.
.br
.RB "[\|" \-A\c
.I architecture\c
\&\|] 
.RB "[\|" "\-b\ "\c
.I input-format\c
\&\|] 
.RB "[\|" \-Bstatic "\|]"  
.RB "[\|" \-Bdynamic "\|]"  
.RB "[\|" \-Bsymbolic "\|]"  
.RB "[\|" "\-c\ "\c
.I commandfile\c
\&\|] 
.RB "[\|" \-\-cref "\|]"
.RB "[\|" \-d | \-dc | \-dp\c
\|]
.br
.RB "[\|" "\-defsym\ "\c
.I symbol\c
\&=\c
.I expression\c
\&\|]
.RB "[\|" \-\-demangle "\|]"
.RB "[\|" \-\-no\-demangle "\|]"
.RB "[\|" "\-e\ "\c
.I entry\c
\&\|] 
.RB "[\|" \-embedded\-relocs "\|]"
.RB "[\|" \-E "\|]" 
.RB "[\|" \-export\-dynamic "\|]"
.RB "[\|" "\-f\ "\c
.I name\c
\&\|]
.RB "[\|" "\-\-auxiliary\ "\c
.I name\c
\&\|]
.RB "[\|" "\-F\ "\c
.I name\c
\&\|]
.RB "[\|" "\-\-filter\ "\c
.I name\c
\&\|]
.RB "[\|" "\-format\ "\c
.I input-format\c
\&\|] 
.RB "[\|" \-g "\|]" 
.RB "[\|" \-G
.I size\c
\&\|]
.RB "[\|" "\-h\ "\c
.I name\c
\&\|]
.RB "[\|" "\-soname\ "\c
.I name\c
\&\|]
.RB "[\|" \-\-help "\|]"
.RB "[\|" \-i "\|]"
.RB "[\|" \-l\c
.I ar\c
\&\|] 
.RB "[\|" \-L\c
.I searchdir\c
\&\|] 
.RB "[\|" \-M "\|]" 
.RB "[\|" \-Map
.I mapfile\c
\&\|] 
.RB "[\|" \-m
.I emulation\c
\&\|] 
.RB "[\|" \-n | \-N "\|]" 
.RB "[\|" \-noinhibit-exec "\|]" 
.RB "[\|" \-no\-keep\-memory "\|]" 
.RB "[\|" \-no\-warn\-mismatch "\|]" 
.RB "[\|" \-O\c
.I level\c
\&\|]
.RB "[\|" "\--oformat\ "\c
.I output-format\c
\&\|] 
.RB "[\|" "\-R\ "\c
.I filename\c
\&\|]
.RB "[\|" \-relax "\|]"
.RB "[\|" \-r | \-Ur "\|]" 
.RB "[\|" "\-rpath\ "\c
.I directory\c
\&\|]
.RB "[\|" "\-rpath\-link\ "\c
.I directory\c
\&\|]
.RB "[\|" \-S "\|]" 
.RB "[\|" \-s "\|]" 
.RB "[\|" \-shared "\|]" 
.RB "[\|" \-sort\-common "\|]" 
.RB "[\|" "\-split\-by\-reloc\ "\c
.I count\c
\&\|]
.RB "[\|" \-split\-by\-file "\|]" 
.RB "[\|" "\-T\ "\c
.I commandfile\c
\&\|]  
.RB "[\|" "\-\-section\-start\ "\c
.I sectionname\c
\&=\c
.I sectionorg\c
\&\|]
.RB "[\|" "\-Ttext\ "\c
.I textorg\c
\&\|] 
.RB "[\|" "\-Tdata\ "\c
.I dataorg\c
\&\|] 
.RB "[\|" "\-Tbss\ "\c
.I bssorg\c
\&\|]
.RB "[\|" \-t "\|]" 
.RB "[\|" "\-u\ "\c
.I sym\c
\&]
.RB "[\|" \-V "\|]"
.RB "[\|" \-v "\|]"
.RB "[\|" \-\-verbose "\|]"
.RB "[\|" \-\-version "\|]"
.RB "[\|" \-warn\-common "\|]" 
.RB "[\|" \-warn\-constructors "\|]" 
.RB "[\|" \-warn\-multiple\-gp "\|]" 
.RB "[\|" \-warn\-once "\|]" 
.RB "[\|" \-warn\-section\-align "\|]" 
.RB "[\|" \-\-whole\-archive "\|]" 
.RB "[\|" \-\-no\-whole\-archive "\|]" 
.RB "[\|" "\-\-wrap\ "\c
.I symbol\c
\&\|]
.RB "[\|" \-X "\|]" 
.RB "[\|" \-x "\|]" 
.ad b
.hy 1
.SH DESCRIPTION
\c
.B ld\c
\& combines a number of object and archive files, relocates
their data and ties up symbol references. Often the last step in
building a new compiled program to run is a call to \c
.B ld\c
\&.

\c
.B ld\c
\& accepts Linker Command Language files 
to provide explicit and total control over the linking process.
This man page does not describe the command language; see the `\|\c
.B ld\c
\|' entry in `\|\c
.B info\c
\|', or the manual
.I
ld: the GNU linker
\&, for full details on the command language and on other aspects of
the GNU linker. 

This version of \c
.B ld\c
\& uses the general purpose BFD libraries
to operate on object files. This allows \c
.B ld\c
\& to read, combine, and
write object files in many different formats\(em\&for example, COFF or
\c
.B a.out\c
\&.  Different formats may be linked together to produce any
available kind of object file.  You can use `\|\c
.B objdump \-i\c
\|' to get a list of formats supported on various architectures; see 
.BR objdump ( 1 ).

Aside from its flexibility, the GNU linker is more helpful than other
linkers in providing diagnostic information.  Many linkers abandon
execution immediately upon encountering an error; whenever possible,
\c
.B ld\c
\& continues executing, allowing you to identify other errors
(or, in some cases, to get an output file in spite of the error).

The GNU linker \c
.B ld\c
\& is meant to cover a broad range of situations,
and to be as compatible as possible with other linkers.  As a result,
you have many choices to control its behavior through the command line,
and through environment variables.

.SH OPTIONS
The plethora of command-line options may seem intimidating, but in
actual practice few of them are used in any particular context.
For instance, a frequent use of \c
.B ld\c
\& is to link standard Unix
object files on a standard, supported Unix system.  On such a system, to
link a file \c
.B hello.o\c
\&:
.sp
.br
$\ ld\ \-o\ output\ /lib/crt0.o\ hello.o\ \-lc
.br
.sp
This tells \c
.B ld\c
\& to produce a file called \c
.B output\c
\& as the
result of linking the file \c
.B /lib/crt0.o\c
\& with \c
.B hello.o\c
\& and
the library \c
.B libc.a\c
\& which will come from the standard search
directories.

The command-line options to \c
.B ld\c
\& may be specified in any order, and
may be repeated at will.  For the most part, repeating an option with a
different argument will either have no further effect, or override prior
occurrences (those further to the left on the command line) of an
option.  

The exceptions\(em\&which may meaningfully be used more than once\(em\&are
\c
.B \-A\c
\&, \c
.B \-b\c
\& (or its synonym \c
.B \-format\c
\&), \c
.B \-defsym\c
\&, \c
.B \-\-section\-start\c
\&, \c
.B \-L\c
\&, \c
.B \-l\c
\&, \c
.B \-R\c
\&, and \c
.B \-u\c
\&.

The list of object files to be linked together, shown as \c
.I objfile\c
\&,
may follow, precede, or be mixed in with command-line options; save that
an \c
.I objfile\c
\& argument may not be placed between an option flag and
its argument.

Usually the linker is invoked with at least one object file, but other
forms of binary input files can also be specified with \c
.B \-l\c
\&,
\c
.B \-R\c
\&, and the script command language.  If \c
.I no\c
\& binary input
files at all are specified, the linker does not produce any output, and
issues the message `\|\c
.B No input files\c
\|'.

Option arguments must either follow the option letter without intervening
whitespace, or be given as separate arguments immediately following the
option that requires them.

.TP
.BI "-A" "architecture"
In the current release of \c
.B ld\c
\&, this option is useful only for the
Intel 960 family of architectures.  In that \c
.B ld\c
\& configuration, the
\c
.I architecture\c
\& argument is one of the two-letter names identifying
members of the 960 family; the option specifies the desired output
target, and warns of any incompatible instructions in the input files.
It also modifies the linker's search strategy for archive libraries, to
support the use of libraries specific to each particular
architecture, by including in the search loop names suffixed with the
string identifying the architecture.

For example, if your \c
.B ld\c
\& command line included `\|\c
.B \-ACA\c
\|' as
well as `\|\c
.B \-ltry\c
\|', the linker would look (in its built-in search
paths, and in any paths you specify with \c
.B \-L\c
\&) for a library with
the names
.sp
.br
try
.br
libtry.a
.br
tryca
.br
libtryca.a
.br
.sp

The first two possibilities would be considered in any event; the last
two are due to the use of `\|\c
.B \-ACA\c
\|'.

Future releases of \c
.B ld\c
\& may support similar functionality for
other architecture families.

You can meaningfully use \c
.B \-A\c
\& more than once on a command line, if
an architecture family allows combination of target architectures; each
use will add another pair of name variants to search for when \c
.B \-l
specifies a library.

.TP
.BI "\-b " "input-format"
Specify the binary format for input object files that follow this option
on the command line.  You don't usually need to specify this, as
\c
.B ld\c
\& is configured to expect as a default input format the most
usual format on each machine.  \c
.I input-format\c
\& is a text string, the
name of a particular format supported by the BFD libraries.  
\c
.B \-format \c
.I input-format\c
\&\c
\& has the same effect, as does the script command
.BR TARGET .

You may want to use this option if you are linking files with an unusual
binary format.  You can also use \c
.B \-b\c
\& to switch formats explicitly (when
linking object files of different formats), by including
\c
.B \-b \c
.I input-format\c
\&\c
\& before each group of object files in a
particular format.  

The default format is taken from the environment variable
.B GNUTARGET\c
\&.  You can also define the input
format from a script, using the command \c
.B TARGET\c
\&.

.TP
.B \-Bstatic 
Do not link against shared libraries.  This is only meaningful on
platforms for which shared libraries are supported.

.TP
.B \-Bdynamic
Link against dynamic libraries.  This is only meaningful on platforms
for which shared libraries are supported.  This option is normally the
default on such platforms.

.TP
.B \-Bsymbolic
When creating a shared library, bind references to global symbols to
the definition within the shared library, if any.  Normally, it is
possible for a program linked against a shared library to override the
definition within the shared library.  This option is only meaningful
on ELF platforms which support shared libraries.

.TP
.BI "\-c " "commandfile"
Directs \c
.B ld\c
\& to read link commands from the file
\c
.I commandfile\c
\&.  These commands will completely override \c
.B ld\c
\&'s
default link format (rather than adding to it); \c
.I commandfile\c
\& must
specify everything necessary to describe the target format.


You may also include a script of link commands directly in the command
line by bracketing it between `\|\c
.B {\c
\|' and `\|\c
.B }\c
\|' characters.

.TP
.B \-\-cref
Output a cross reference table.  If a linker map file is being
generated, the cross reference table is printed to the map file.
Otherwise, it is printed on the standard output.

.TP
.B \-d 
.TP
.B \-dc
.TP
.B \-dp
These three options are equivalent; multiple forms are supported for
compatibility with other linkers.  Use any of them to make \c
.B ld
assign space to common symbols even if a relocatable output file is
specified (\c
.B \-r\c
\&).  The script command
\c
.B FORCE_COMMON_ALLOCATION\c
\& has the same effect.

.TP
.BI "-defsym " "symbol" "\fR=\fP" expression
Create a global symbol in the output file, containing the absolute
address given by \c
.I expression\c
\&.  You may use this option as many
times as necessary to define multiple symbols in the command line.  A
limited form of arithmetic is supported for the \c
.I expression\c
\& in this
context: you may give a hexadecimal constant or the name of an existing
symbol, or use \c
.B +\c
\& and \c
.B \-\c
\& to add or subtract hexadecimal
constants or symbols.  If you need more elaborate expressions, consider
using the linker command language from a script.

.TP
.B \-\-demangle
.TP
.B \-\-no\-demangle
These options control whether to demangle symbol names in error
messages and other output.  When the linker is told to demangle, it
tries to present symbol names in a readable fashion: it strips leading
underscores if they are used by the object file format, and converts
C++ mangled symbol names into user readable names.  The linker will
demangle by default unless the environment variable
.B COLLECT_NO_DEMANGLE
is set.  These options may be used to override the default.

.TP
.BI "-e " "entry"\c
\& 
Use \c
.I entry\c
\& as the explicit symbol for beginning execution of your
program, rather than the default entry point.  See the `\|\c
.B ld\c
\|' entry in `\|\c
.B info\c
\|' for a
discussion of defaults and other ways of specifying the
entry point.

.TP
.B \-embedded\-relocs
This option is only meaningful when linking MIPS embedded PIC code,
generated by the
.B \-membedded\-pic
option to the GNU compiler and assembler.  It causes the linker to
create a table which may be used at runtime to relocate any data which
was statically initialized to pointer values.  See the code in
testsuite/ld-empic for details.

.TP
.B \-E
.TP
.B \-export\-dynamic
When creating an ELF file, add all symbols to the dynamic symbol table.
Normally, the dynamic symbol table contains only symbols which are used
by a dynamic object.  This option is needed for some uses of
.I dlopen.

.TP
.BI "-f " "name"
.TP
.BI "--auxiliary " "name"
When creating an ELF shared object, set the internal DT_AUXILIARY field
to the specified name.  This tells the dynamic linker that the symbol
table of the shared object should be used as an auxiliary filter on the
symbol table of the shared object
.I name.

.TP
.BI "-F " "name"
.TP
.BI "--filter " "name"
When creating an ELF shared object, set the internal DT_FILTER field to
the specified name.  This tells the dynamic linker that the symbol table
of the shared object should be used as a filter on the symbol table of
the shared object
.I name.

.TP
.BI "\-format " "input\-format"
Synonym for \c
.B \-b\c
\& \c
.I input\-format\c
\&.

.TP
.B \-g
Accepted, but ignored; provided for compatibility with other tools.

.TP
.BI "\-G " "size"\c
Set the maximum size of objects to be optimized using the GP register
to
.I size
under MIPS ECOFF.  Ignored for other object file formats.

.TP
.BI "-h " "name"
.TP
.BI "-soname " "name"
When creating an ELF shared object, set the internal DT_SONAME field to
the specified name.  When an executable is linked with a shared object
which has a DT_SONAME field, then when the executable is run the dynamic
linker will attempt to load the shared object specified by the DT_SONAME
field rather than the using the file name given to the linker.

.TP
.B \-\-help
Print a summary of the command-line options on the standard output and exit.
This option and
.B \-\-version
begin with two dashes instead of one
for compatibility with other GNU programs.  The other options start with
only one dash for compatibility with other linkers.

.TP
.B \-i
Perform an incremental link (same as option \c
.B \-r\c
\&).

.TP
.BI "\-l" "ar"\c
\& 
Add an archive file \c
.I ar\c
\& to the list of files to link.  This 
option may be used any number of times.  \c
.B ld\c
\& will search its
path-list for occurrences of \c
.B lib\c
.I ar\c
\&.a\c
\& for every \c
.I ar
specified.

.TP
.BI "\-L" "searchdir"
This command adds path \c
.I searchdir\c
\& to the list of paths that
\c
.B ld\c
\& will search for archive libraries.  You may use this option
any number of times.

The default set of paths searched (without being specified with
\c
.B \-L\c
\&) depends on what emulation mode \c
.B ld\c
\& is using, and in
some cases also on how it was configured.    The
paths can also be specified in a link script with the \c
.B SEARCH_DIR
command.

.TP
.B \-M 
Print (to the standard output file) a link map\(em\&diagnostic information
about where symbols are mapped by \c
.B ld\c
\&, and information on global
common storage allocation.

.TP
.BI "\-Map " "mapfile"\c
Print to the file
.I mapfile
a link map\(em\&diagnostic information
about where symbols are mapped by \c
.B ld\c
\&, and information on global
common storage allocation.

.TP
.BI "\-m " "emulation"\c
Emulate the
.I emulation
linker.  You can list the available emulations with the
.I \-\-verbose
or
.I \-V
options.  This option overrides the compiled-in default, which is the
system for which you configured
.BR ld .

.TP
.B \-N 
specifies readable and writable \c
.B text\c
\& and \c
.B data\c
\& sections. If
the output format supports Unix style magic numbers, the output is
marked as \c
.B OMAGIC\c
\&.

When you use the `\|\c
.B \-N\c
\&\|' option, the linker does not page-align the
data segment.

.TP
.B \-n 
sets the text segment to be read only, and \c
.B NMAGIC\c
\& is written
if possible.

.TP
.B \-noinhibit\-exec
Normally, the linker will not produce an output file if it encounters
errors during the link process.  With this flag, you can specify that
you wish the output file retained even after non-fatal errors.

.TP
.B \-no\-keep\-memory
The linker normally optimizes for speed over memory usage by caching
the symbol tables of input files in memory.  This option tells the
linker to instead optimize for memory usage, by rereading the symbol
tables as necessary.  This may be required if the linker runs out of
memory space while linking a large executable.

.TP
.B \-no\-warn\-mismatch
Normally the linker will give an error if you try to link together
input files that are mismatched for some reason, perhaps because they
have been compiled for different processors or for different
endiannesses.  This option tells the linker that it should silently
permit such possible errors.  This option should only be used with
care, in cases when you have taken some special action that ensures
that the linker errors are inappropriate.

.TP
.BI "\-o " "output"
.I output\c
\& is a name for the program produced by \c
.B ld\c
\&; if this
option is not specified, the name `\|\c
.B a.out\c
\|' is used by default.  The
script command \c
.B OUTPUT\c
\& can also specify the output file name.

.TP
.BI "\-O" "level"
Generate optimized output files.  This might use significantly more
time and therefore probably should be enabled only for generating the
final binary.
\c
.I level\c
\& is supposed to be a numeric value.  Any value greater than zero enables
the optimizations.

.TP
.BI "\--oformat " "output\-format"
Specify the binary format for the output object file.
You don't usually need to specify this, as
\c
.B ld\c
\& is configured to produce as a default output format the most
usual format on each machine.  \c
.I output-format\c
\& is a text string, the
name of a particular format supported by the BFD libraries.  
The script command
.B OUTPUT_FORMAT
can also specify the output format, but this option overrides it.

.TP
.BI "\-R " "filename"
Read symbol names and their addresses from \c
.I filename\c
\&, but do not
relocate it or include it in the output.  This allows your output file
to refer symbolically to absolute locations of memory defined in other
programs.

.TP
.B \-relax
An option with machine dependent effects.  Currently this option is only
supported on the H8/300.

On some platforms, use this option to perform global optimizations that
become possible when the linker resolves addressing in your program, such
as relaxing address modes and synthesizing new instructions in the
output object file.  

On platforms where this is not supported, `\|\c
.B \-relax\c
\&\|' is accepted, but has no effect.

.TP
.B \-r 
Generates relocatable output\(em\&i.e., generate an output file that can in
turn serve as input to \c
.B ld\c
\&.  This is often called \c
.I partial
linking\c
\&.  As a side effect, in environments that support standard Unix
magic numbers, this option also sets the output file's magic number to
\c
.B OMAGIC\c
\&.
If this option is not specified, an absolute file is produced.  When
linking C++ programs, this option \c
.I will not\c
\& resolve references to
constructors; \c
.B \-Ur\c
\& is an alternative. 

This option does the same as \c
.B \-i\c
\&.

.TP
.B \-rpath\ \fIdirectory
Add a directory to the runtime library search path.  This is used when
linking an ELF executable with shared objects.  All 
.B \-rpath
arguments are concatenated and passed to the runtime linker, which uses
them to locate shared objects at runtime.  The
.B \-rpath
option is also used when locating shared objects which are needed by
shared objects explicitly included in the link; see the description of
the
.B \-rpath\-link
option.  If
.B \-rpath
is not used when linking an ELF executable, the contents of the
environment variable
.B LD_RUN_PATH
will be used if it is defined.

The
.B \-rpath
option may also be used on SunOS.  By default, on SunOS, the linker
will form a runtime search path out of all the
.B \-L
options it is given.  If a
.B \-rpath
option is used, the runtime search path will be formed exclusively
using the
.B \-rpath
options, ignoring
the
.B \-L
options.  This can be useful when using gcc, which adds many
.B \-L
options which may be on NFS mounted filesystems.

.TP
.B \-rpath\-link\ \fIdirectory
When using ELF or SunOS, one shared library may require another.  This
happens when an
.B ld\ \-shared
link includes a shared library as one of the input files.

When the linker encounters such a dependency when doing a non-shared,
non-relocateable link, it will automatically try to locate the required
shared library and include it in the link, if it is not included
explicitly.  In such a case, the
.B \-rpath\-link
option specifies the first set of directories to search.  The
.B \-rpath\-link
option may specify a sequence of directory names either by specifying
a list of names separated by colons, or by appearing multiple times.

If the required shared library is not found, the linker will issue a
warning and continue with the link.

.TP
.B \-S 
Omits debugger symbol information (but not all symbols) from the output file.

.TP
.B \-s 
Omits all symbol information from the output file.

.TP
.B \-shared
Create a shared library.  This is currently only supported on ELF and
SunOS platforms (on SunOS it is not required, as the linker will
automatically create a shared library when there are undefined symbols
and the
.B \-e
option is not used).

.TP
.B \-sort\-common
Normally, when
.B ld
places the global common symbols in the appropriate output sections,
it sorts them by size.  First come all the one byte symbols, then all
the two bytes, then all the four bytes, and then everything else.
This is to prevent gaps between symbols due to
alignment constraints.  This option disables that sorting.

.TP
.B \-split\-by\-reloc\ \fIcount
Trys to creates extra sections in the output file so that no single
output section in the file contains more than
.I count
relocations.
This is useful when generating huge relocatable for downloading into
certain real time kernels with the COFF object file format; since COFF
cannot represent more than 65535 relocations in a single section.
Note that this will fail to work with object file formats which do not
support arbitrary sections.  The linker will not split up individual
input sections for redistribution, so if a single input section
contains more than
.I count
relocations one output section will contain that many relocations.

.TP
.B \-split\-by\-file
Similar to
.B \-split\-by\-reloc
but creates a new output section for each input file.

.TP
.BI "--section-start " "sectionname" "\fR=\fP"org
Locate a section in the output file at the absolute
address given by \c
.I org\c
\&.  \c
\c
.I org\c
\& must be a hexadecimal integer.
You may use this option as many
times as necessary to locate multiple sections in the command
line.  If you need more elaborate expressions, consider
using the linker command language from a script.

.TP
.BI "\-Tbss " "org"\c
.TP
.BI "\-Tdata " "org"\c
.TP
.BI "\-Ttext " "org"\c
Use \c
.I org\c
\& as the starting address for\(em\&respectively\(em\&the
\c
.B bss\c
\&, \c
.B data\c
\&, or the \c
.B text\c
\& segment of the output file.
\c
.I org\c
\& must be a hexadecimal integer.

.TP
.BI "\-T " "commandfile"
Equivalent to \c
.B \-c \c
.I commandfile\c
\&\c
\&; supported for compatibility with
other tools.  

.TP
.B \-t 
Prints names of input files as \c
.B ld\c
\& processes them.

.TP
.BI "\-u " "sym"
Forces \c
.I sym\c
\& to be entered in the output file as an undefined symbol.
This may, for example, trigger linking of additional modules from
standard libraries.  \c
.B \-u\c
\& may be repeated with different option
arguments to enter additional undefined symbols.

.TP
.B \-Ur 
For anything other than C++ programs, this option is equivalent to
\c
.B \-r\c
\&: it generates relocatable output\(em\&i.e., an output file that can in
turn serve as input to \c
.B ld\c
\&.  When linking C++ programs, \c
.B \-Ur
.I will\c
\& resolve references to constructors, unlike \c
.B \-r\c
\&.

.TP
.B \-\-verbose
Display the version number for \c
.B ld
and list the supported emulations.
Display which input files can and can not be opened.

.TP
.B \-v, \-V
Display the version number for \c
.B ld\c
\&.
The
.B \-V
option also lists the supported emulations.

.TP
.B \-\-version
Display the version number for \c
.B ld
and exit.

.TP
.B \-warn\-common
Warn when a common symbol is combined with another common symbol or with
a symbol definition.  Unix linkers allow this somewhat sloppy practice,
but linkers on some other operating systems do not.  This option allows
you to find potential problems from combining global symbols.

.TP
.B \-warn\-constructors
Warn if any global constructors are used.  This is only useful for a
few object file formats.  For formats like COFF or ELF, the linker can
not detect the use of global constructors.

.TP
.B \-warn\-multiple\-gp
Warn if the output file requires multiple global-pointer values.  This
option is only meaningful for certain processors, such as the Alpha.

.TP
.B \-warn\-once
Only warn once for each undefined symbol, rather than once per module
which refers to it.

.TP
.B \-warn\-section\-align
Warn if the address of an output section is changed because of
alignment.  Typically, the alignment will be set by an input section.
The address will only be changed if it not explicitly specified; that
is, if the SECTIONS command does not specify a start address for the
section.

.TP
.B \-\-whole\-archive
For each archive mentioned on the command line after the
.B \-\-whole\-archive
option, include every object file in the archive in the link, rather
than searching the archive for the required object files.  This is
normally used to turn an archive file into a shared library, forcing
every object to be included in the resulting shared library.

.TP
.B \-\-no\-whole\-archive
Turn off the effect of the
.B \-\-whole\-archive
option for archives which appear later on the command line.

.TP
.BI "--wrap " "symbol"
Use a wrapper function for 
.I symbol.
Any undefined reference to
.I symbol
will be resolved to
.BI "__wrap_" "symbol".
Any undefined reference to
.BI "__real_" "symbol"
will be resolved to
.I symbol.

.TP
.B \-X 
Delete all temporary local symbols.  For most targets, this is all local
symbols whose names begin with `\|\c
.B L\c
\|'.

.TP
.B \-x
Delete all local symbols.

.PP

.SH ENVIRONMENT
\c
You can change the behavior of
.B ld\c
\& with the environment variable \c
.B GNUTARGET\c
\&.

\c
.B GNUTARGET\c
\& determines the input-file object format if you don't
use \c
.B \-b\c
\& (or its synonym \c
.B \-format\c
\&).  Its value should be one
of the BFD names for an input format.  If there is no
\c
.B GNUTARGET\c
\& in the environment, \c
.B ld\c
\& uses the natural format
of the host. If \c
.B GNUTARGET\c
\& is set to \c
.B default\c
\& then BFD attempts to discover the
input format by examining binary input files; this method often
succeeds, but there are potential ambiguities, since there is no method
of ensuring that the magic number used to flag object-file formats is
unique.  However, the configuration procedure for BFD on each system
places the conventional format for that system first in the search-list,
so ambiguities are resolved in favor of convention.

.PP

.SH "SEE ALSO"

.BR objdump ( 1 )
.br
.br
.RB "`\|" ld "\|' and `\|" binutils "\|'"
entries in
.B info\c
.br
.I 
ld: the GNU linker\c
, Steve Chamberlain and Roland Pesch;
.I
The GNU Binary Utilities\c
, Roland H. Pesch.

.SH COPYING
Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 1998, 2000 Free Software Foundation, Inc.
.PP
This document is distributed under the terms of the GNU Free
Documentation License, version 1.1.  That license is described in the
sources for this manual page, but it is not displayed here in order to
make this manual more consise.  Copies of this license can also be
obtained from: http://www.gnu.org/copyleft/.

\"  .SH GNU Free Documentation License
\"    Version 1.1, March 2000

\"    Copyright (C) 2000  Free Software Foundation, Inc.
\"    59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     
\"    Everyone is permitted to copy and distribute verbatim
\"    copies of this license document, but changing it is
\"    not allowed.
\"  .PP
\"  0. PREAMBLE
\"  .PP
\"  The purpose of this License is to make a manual, textbook, or other
\"  written 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.
\"  .PP
\"  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.
\"  .PP
\"  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 to software manuals;
\"  it can be used for any textual work, regardless of subject matter or
\"  whether it is published as a printed book.  We recommend this License
\"  principally for works whose purpose is instruction or reference.
\"  .PP
\"  1. APPLICABILITY AND DEFINITIONS
\"  .PP
\"  This License applies to any manual or other work that contains a
\"  notice placed by the copyright holder saying it can be distributed
\"  under the terms of this License.  The "Document", below, refers to any
\"  such manual or work.  Any member of the public is a licensee, and is
\"  addressed as "you".
\"  .PP
\"  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 into another language.
\"  .PP
\"  A "Secondary Section" is a named appendix or a front-matter section of
\"  the Document that 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.  (For example, 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 regarding
\"  them.
\"  .PP
\"  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 under this License.
\"  .PP
\"  The "Cover Texts" are certain short passages of text that are listed,
\"  as Front-Cover Texts or Back-Cover Texts, in the notice that says that
\"  the Document is released under this License.
\"  .PP
\"  A "Transparent" copy of the Document means a machine-readable copy,
\"  represented in a format whose specification is available to the
\"  general public, whose contents can be viewed and edited directly and
\"  straightforwardly with generic text editors or (for images composed of
\"  pixels) generic paint programs or (for drawings) some widely available
\"  drawing editor, and that is suitable for input to text formatters or
\"  for automatic translation to a variety of formats suitable for input
\"  to text formatters.  A copy made in an otherwise Transparent file
\"  format whose markup has been designed to thwart or discourage
\"  subsequent modification by readers is not Transparent.  A copy that is
\"  not "Transparent" is called "Opaque".
\"  .PP
\"  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 DTD, and standard-conforming simple
\"  HTML designed for human modification.  Opaque formats include
\"  PostScript, PDF, 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 produced by some word processors for output
\"  purposes only.
\"  .PP
\"  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 the title 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.
\"  .PP
\"  2. VERBATIM COPYING
\"  .PP
\"  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, and that 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.
\"  .PP
\"  You may also lend copies, under the same conditions stated above, and
\"  you may publicly display copies.
\"  .PP
\"  3. COPYING IN QUANTITY
\"  .PP
\"  If you publish printed copies 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, all these 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 publisher of 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 the Document and satisfy these conditions, can be treated
\"  as verbatim copying in other respects.
\"  .PP
\"  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 the rest onto adjacent
\"  pages.
\"  .PP
\"  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 Opaque copy, or state in or with each Opaque copy
\"  a publicly-accessible computer-network location containing a complete
\"  Transparent copy of the Document, free of added material, which the
\"  general network-using public has access to download anonymously at no
\"  charge using public-standard network protocols.  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 will remain 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.
\"  .PP
\"  It is requested, but not required, that you contact the authors of the
\"  Document well before redistributing any large number of copies, to give
\"  them a chance to provide you with an updated version of the Document.
\"  .PP
\"  4. MODIFICATIONS
\"  .PP
\"  You may copy and distribute a Modified Version of the Document under
\"  the conditions of 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:
\"  .PP
\"  A. Use in the Title Page (and on the covers, if any) a title distinct
\"  from that of the Document, and from those of previous versions
\"  (which should, if there were any, be listed in the History section
\"  of the Document).  You may use the same title as a previous version
\"  if the original publisher of that version gives permission.
\"  .PP
\"  B. List on the Title Page, as authors, one or more persons or entities
\"  responsible for authorship of the modifications in the Modified
\"  Version, together with at least five of the principal authors of the
\"  Document (all of its principal authors, if it has less than five).
\"  .PP
\"  C. State on the Title page the name of the publisher of the
\"  Modified Version, as the publisher.
\"  .PP
\"  D. Preserve all the copyright notices of the Document.
\"  .PP
\"  E. Add an appropriate copyright notice for your modifications
\"  adjacent to the other copyright notices.
\"  .PP
\"  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 form shown in the Addendum below.
\"  Preserve in that license notice the full lists of Invariant Sections
\"  and required Cover Texts given in the Document's license notice.
\"  .PP
\"  H. Include an unaltered copy of this License.
\"  .PP
\"  I. Preserve the section entitled "History", and 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.
\"  .PP
\"  J. Preserve the network location, if any, given in the Document for
\"  public access to a 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 published at
\"  least four years before the Document itself, or if the original
\"  publisher of the version it refers to gives permission.
\"  .PP
\"  K. In any section entitled "Acknowledgements" or "Dedications",
\"  preserve the section's title, and preserve in the section all the
\"  substance and tone of each of the contributor acknowledgements
\"  and/or dedications given therein.
\"  .PP
\"  L. Preserve all the Invariant Sections of the Document,
\"  unaltered in their text and in their titles.  Section numbers
\"  or the equivalent are not considered part of the section titles.
\"  .PP
\"  M. Delete any section entitled "Endorsements".  Such a section
\"  may not be included in the Modified Version.
\"  .PP
\"  N. Do not retitle any existing section as "Endorsements"
\"  or to conflict in title with any Invariant Section.
\"  .PP
\"  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 at your option designate some or all
\"  of these sections as invariant.  To do this, add their titles to the
\"  list of Invariant Sections in the Modified Version's license notice.
\"  These titles must be distinct from any other section titles.
\"  .PP
\"  You may add a section entitled "Endorsements", provided it contains
\"  nothing but endorsements of your Modified Version by various
\"  parties--for example, statements of peer review or that the text has
\"  been approved by an organization as the authoritative definition of a
\"  standard.
\"  .PP
\"  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 added by (or
\"  through arrangements made by) any one entity.  If the Document already
\"  includes a cover text for the same cover, previously added by you or
\"  by arrangement 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.
\"  .PP
\"  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.
\"  .PP

\"  5. COMBINING DOCUMENTS
\"  .PP
\"  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.
\"  .PP
\"  The combined work need only contain one copy of this License, and
\"  multiple identical Invariant 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 combined work.
\"  .PP
\"  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."
\"  .PP

\"  6. COLLECTIONS OF DOCUMENTS
\"  .PP
\"  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 other respects.
\"  .PP
\"  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 of that document.
\"  .PP

\"  7. AGGREGATION WITH INDEPENDENT WORKS
\"  .PP
\"  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, does not as a whole count as a Modified Version
\"  of the Document, provided no compilation copyright is claimed for the
\"  compilation.  Such a compilation is called an "aggregate", and this
\"  License does not apply to the other self-contained works thus compiled
\"  with the Document, on account of their being thus compiled, if they
\"  are not themselves derivative works of the Document.
\"  .PP
\"  If the Cover Text requirement of section 3 is applicable to these
\"  copies of the Document, then if the Document is less than one quarter
\"  of the entire aggregate, the Document's Cover Texts may be placed on
\"  covers that surround only the Document within the aggregate.
\"  Otherwise they must appear on covers around the whole aggregate.
\"  .PP

\"  8. TRANSLATION
\"  .PP
\"  Translation is considered a kind of modification, so you may
\"  distribute translations of the Document under the terms of section 4.
\"  Replacing Invariant Sections with translations requires special
\"  permission from their copyright holders, but you may include
\"  translations of some or all Invariant Sections in addition to the
\"  original versions of these Invariant Sections.  You may include a
\"  translation of this License provided that you also include the
\"  original English version of this License.  In case of a disagreement
\"  between the translation and the original English version of this
\"  License, the original English version will prevail.
\"  .PP

\"  9. TERMINATION
\"  .PP
\"  You may not copy, modify, sublicense, or distribute the Document except
\"  as expressly provided for under this License.  Any other attempt to
\"  copy, modify, sublicense or distribute the Document is void, and will
\"  automatically terminate your rights under this License.  However,
\"  parties who have received copies, or rights, from you under this
\"  License will not have their licenses terminated so long as such
\"  parties remain in full compliance.
\"  .PP

\"  10. FUTURE REVISIONS OF THIS LICENSE
\"  .PP
\"  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/.
\"  .PP
\"  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.
\"  .PP

\"  ADDENDUM: How to use this License for your documents
\"  .PP
\"  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:
\"  .PP
\"      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 1.1 or any later
\"      version published by the Free Software Foundation;
\"      with the Invariant Sections being LIST THEIR TITLES,
\"      with the Front-Cover Texts being LIST, and with the
\"      Back-Cover Texts being LIST.  A copy of the license
\"      is included in the section entitled "GNU Free
\"      Documentation License".
\"  .PP
\"  If you have no Invariant Sections, write "with no Invariant Sections"
\"  instead of saying which ones are invariant.  If you have no
\"  Front-Cover Texts, write "no Front-Cover Texts" instead of
\"  "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
\"  .PP
\"  If your document contains nontrivial examples of program code, we
\"  recommend releasing these examples in parallel under your choice of
\"  free software license, such as the GNU General Public License,
\"  to permit their use in free software.