ld.texinfo

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@item --noinhibit-exec
Retain the executable output file whenever it is still usable.
Normally, the linker will not produce an output file if it encounters
errors during the link process; it exits without writing an output file
when it issues any error whatsoever.

@ifclear SingleFormat
@kindex --oformat
@item --oformat @var{output-format}
@code{ld} may be configured to support more than one kind of object
file.  If your @code{ld} is configured this way, you can use the
@samp{--oformat} option to specify the binary format for the output
object file.  Even when @code{ld} is configured to support alternative
object formats, you don't usually need to specify this, as @code{ld}
should be configured to produce as a default output format the most
usual format on each machine.  @var{output-format} is a text string, the
name of a particular format supported by the BFD libraries.  (You can
list the available binary formats with @samp{objdump -i}.)  The script
command @code{OUTPUT_FORMAT} can also specify the output format, but
this option overrides it.  @xref{BFD}.
@end ifclear

@kindex -qmagic
@item -qmagic
This option is ignored for Linux compatibility.

@kindex -Qy
@item -Qy
This option is ignored for SVR4 compatibility.

@kindex --relax
@cindex synthesizing linker
@cindex relaxing addressing modes
@item --relax
An option with machine dependent effects.
@ifset GENERIC
This option is only supported on a few targets.
@end ifset
@ifset H8300
@xref{H8/300,,@code{ld} and the H8/300}.
@end ifset
@ifset I960
@xref{i960,, @code{ld} and the Intel 960 family}.
@end ifset


On some platforms, the @samp{--relax} option performs global
optimizations that become possible when the linker resolves addressing
in the program, such as relaxing address modes and synthesizing new
instructions in the output object file.

On some platforms these link time global optimizations may make symbolic
debugging of the resulting executable impossible.
@ifset GENERIC
This is known to be
the case for the Matsushita MN10200 and MN10300 family of processors.
@end ifset

@ifset GENERIC
On platforms where this is not supported, @samp{--relax} is accepted,
but ignored.
@end ifset

@cindex retaining specified symbols
@cindex stripping all but some symbols
@cindex symbols, retaining selectively
@item --retain-symbols-file @var{filename}
Retain @emph{only} the symbols listed in the file @var{filename},
discarding all others.  @var{filename} is simply a flat file, with one
symbol name per line.  This option is especially useful in environments
@ifset GENERIC
(such as VxWorks)
@end ifset
where a large global symbol table is accumulated gradually, to conserve
run-time memory.

@samp{--retain-symbols-file} does @emph{not} discard undefined symbols,
or symbols needed for relocations.

You may only specify @samp{--retain-symbols-file} once in the command
line.  It overrides @samp{-s} and @samp{-S}.

@ifset GENERIC
@item -rpath @var{dir}
@cindex runtime library search path
@kindex -rpath
Add a directory to the runtime library search path.  This is used when
linking an ELF executable with shared objects.  All @code{-rpath}
arguments are concatenated and passed to the runtime linker, which uses
them to locate shared objects at runtime.  The @code{-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
@code{-rpath-link} option.  If @code{-rpath} is not used when linking an
ELF executable, the contents of the environment variable
@code{LD_RUN_PATH} will be used if it is defined.

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

For compatibility with other ELF linkers, if the @code{-R} option is
followed by a directory name, rather than a file name, it is treated as
the @code{-rpath} option.
@end ifset

@ifset GENERIC
@cindex link-time runtime library search path
@kindex -rpath-link
@item -rpath-link @var{DIR}
When using ELF or SunOS, one shared library may require another.  This
happens when an @code{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-relocatable 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 @code{-rpath-link} option
specifies the first set of directories to search.  The
@code{-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.

This option should be used with caution as it overrides the search path
that may have been hard compiled into a shared library. In such a case it
is possible to use unintentionally a different search path than the
runtime linker would do.

The linker uses the following search paths to locate required shared
libraries.
@enumerate
@item
Any directories specified by @code{-rpath-link} options.
@item
Any directories specified by @code{-rpath} options.  The difference
between @code{-rpath} and @code{-rpath-link} is that directories
specified by @code{-rpath} options are included in the executable and
used at runtime, whereas the @code{-rpath-link} option is only effective
at link time. It is for the native linker only.
@item
On an ELF system, if the @code{-rpath} and @code{rpath-link} options
were not used, search the contents of the environment variable
@code{LD_RUN_PATH}. It is for the native linker only.
@item
On SunOS, if the @code{-rpath} option was not used, search any
directories specified using @code{-L} options.
@item
For a native linker, the contents of the environment variable
@code{LD_LIBRARY_PATH}.
@item
For a native ELF linker, the directories in @code{DT_RUNPATH} or
@code{DT_RPATH} of a shared library are searched for shared
libraries needed by it. The @code{DT_RPATH} entries are ignored if
@code{DT_RUNPATH} entries exist.
@item
The default directories, normally @file{/lib} and @file{/usr/lib}.
@item
For a native linker on an ELF system, if the file @file{/etc/ld.so.conf}
exists, the list of directories found in that file.
@end enumerate

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

@kindex -shared
@kindex -Bshareable
@item -shared
@itemx -Bshareable
@cindex shared libraries
Create a shared library.  This is currently only supported on ELF, XCOFF
and SunOS platforms.  On SunOS, the linker will automatically create a
shared library if the @code{-e} option is not used and there are
undefined symbols in the link.

@item --sort-common
@kindex --sort-common
This option tells @code{ld} to sort the common symbols by size when it
places them in the appropriate output sections.  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.

@kindex --split-by-file
@item --split-by-file [@var{size}]
Similar to @code{--split-by-reloc} but creates a new output section for
each input file when @var{size} is reached.  @var{size} defaults to a
size of 1 if not given.

@kindex --split-by-reloc
@item --split-by-reloc [@var{count}]
Tries to creates extra sections in the output file so that no single
output section in the file contains more than @var{count} relocations.
This is useful when generating huge relocatable files 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 @var{count} relocations one output section will contain that
many relocations.  @var{count} defaults to a value of 32768.

@kindex --stats
@item --stats
Compute and display statistics about the operation of the linker, such
as execution time and memory usage.

@kindex --traditional-format
@cindex traditional format
@item --traditional-format
For some targets, the output of @code{ld} is different in some ways from
the output of some existing linker.  This switch requests @code{ld} to
use the traditional format instead.

@cindex dbx
For example, on SunOS, @code{ld} combines duplicate entries in the
symbol string table.  This can reduce the size of an output file with
full debugging information by over 30 percent.  Unfortunately, the SunOS
@code{dbx} program can not read the resulting program (@code{gdb} has no
trouble).  The @samp{--traditional-format} switch tells @code{ld} to not
combine duplicate entries.

@kindex --section-start @var{sectionname}=@var{org}
@item --section-start @var{sectionname}=@var{org}
Locate a section in the output file at the absolute
address given by @var{org}.  You may use this option as many
times as necessary to locate multiple sections in the command
line.
@var{org} must be a single hexadecimal integer;
for compatibility with other linkers, you may omit the leading
@samp{0x} usually associated with hexadecimal values.  @emph{Note:} there
should be no white space between @var{sectionname}, the equals
sign (``@key{=}''), and @var{org}.

@kindex -Tbss @var{org}
@kindex -Tdata @var{org}
@kindex -Ttext @var{org}
@cindex segment origins, cmd line
@item -Tbss @var{org}
@itemx -Tdata @var{org}
@itemx -Ttext @var{org}
Use @var{org} as the starting address for---respectively---the
@code{bss}, @code{data}, or the @code{text} segment of the output file.
@var{org} must be a single hexadecimal integer;
for compatibility with other linkers, you may omit the leading
@samp{0x} usually associated with hexadecimal values.

@kindex --verbose
@cindex verbose
@item --dll-verbose
@itemx --verbose
Display the version number for @code{ld} and list the linker emulations
supported.  Display which input files can and cannot be opened.  Display
the linker script if using a default builtin script.

@kindex --version-script=@var{version-scriptfile}
@cindex version script, symbol versions
@itemx --version-script=@var{version-scriptfile}
Specify the name of a version script to the linker.  This is typically
used when creating shared libraries to specify additional information
about the version heirarchy for the library being created.  This option
is only meaningful on ELF platforms which support shared libraries.
@xref{VERSION}.

@kindex --warn-comon
@cindex warnings, on combining symbols
@cindex combining symbols, warnings on
@item --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.
Unfortunately, some C libraries use this practice, so you may get some
warnings about symbols in the libraries as well as in your programs.

There are three kinds of global symbols, illustrated here by C examples:

@table @samp
@item int i = 1;
A definition, which goes in the initialized data section of the output
file.

@item extern int i;
An undefined reference, which does not allocate space.
There must be either a definition or a common symbol for the
variable somewhere.

@item int i;
A common symbol.  If there are only (one or more) common symbols for a
variable, it goes in the uninitialized data area of the output file.
The linker merges multiple common symbols for the same variable into a
single symbol.  If they are of different sizes, it picks the largest
size.  The linker turns a common symbol into a declaration, if there is
a definition of the same variable.
@end table

The @samp{--warn-common} option can produce five kinds of warnings.
Each warning consists of a pair of lines: the first describes the symbol
just encountered, and the second describes the previous symbol
encountered with the same name.  One or both of the two symbols will be
a common symbol.

@enumerate
@item
Turning a common symbol into a reference, because there is already a
definition for the symbol.
@smallexample
@var{file}(@var{section}): warning: common of `@var{symbol}'
   overridden by definition
@var{file}(@var{section}): warning: defined here
@end smallexample

@item
Turning a common symbol into a reference, because a later definition for
the symbol is encountered.  This is the same as the previous case,
except that the symbols are encountered in a different order.
@smallexample
@var{file}(@var{section}): warning: definition of `@var{symbol}'
   overriding common
@var{file}(@var{section}): warning: common is here
@end smallexample

@item
Merging a common symbol with a previous same-sized common symbol.
@smallexample
@var{file}(@var{section}): warning: multiple common
   of `@var{symbol}'
@var{file}(@var{section}): warning: previous common is here