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| .\" ======================================================================== |
| .\" |
| .IX Title "LD 1" |
| .TH LD 1 "2013-07-21" "binutils-2.23.52.0.2" "GNU Development Tools" |
| .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| .\" way too many mistakes in technical documents. |
| .if n .ad l |
| .nh |
| .SH "NAME" |
| ld \- The GNU linker |
| .SH "SYNOPSIS" |
| .IX Header "SYNOPSIS" |
| ld [\fBoptions\fR] \fIobjfile\fR ... |
| .SH "DESCRIPTION" |
| .IX Header "DESCRIPTION" |
| \&\fBld\fR combines a number of object and archive files, relocates |
| their data and ties up symbol references. Usually the last step in |
| compiling a program is to run \fBld\fR. |
| .PP |
| \&\fBld\fR accepts Linker Command Language files written in |
| a superset of \s-1AT&T\s0's Link Editor Command Language syntax, |
| to provide explicit and total control over the linking process. |
| .PP |
| This man page does not describe the command language; see the |
| \&\fBld\fR entry in \f(CW\*(C`info\*(C'\fR for full details on the command |
| language and on other aspects of the \s-1GNU\s0 linker. |
| .PP |
| This version of \fBld\fR uses the general purpose \s-1BFD\s0 libraries |
| to operate on object files. This allows \fBld\fR to read, combine, and |
| write object files in many different formats\-\-\-for example, \s-1COFF\s0 or |
| \&\f(CW\*(C`a.out\*(C'\fR. Different formats may be linked together to produce any |
| available kind of object file. |
| .PP |
| Aside from its flexibility, the \s-1GNU\s0 linker is more helpful than other |
| linkers in providing diagnostic information. Many linkers abandon |
| execution immediately upon encountering an error; whenever possible, |
| \&\fBld\fR continues executing, allowing you to identify other errors |
| (or, in some cases, to get an output file in spite of the error). |
| .PP |
| The \s-1GNU\s0 linker \fBld\fR 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. |
| .SH "OPTIONS" |
| .IX Header "OPTIONS" |
| The linker supports a plethora of command-line options, but in actual |
| practice few of them are used in any particular context. |
| For instance, a frequent use of \fBld\fR is to link standard Unix |
| object files on a standard, supported Unix system. On such a system, to |
| link a file \f(CW\*(C`hello.o\*(C'\fR: |
| .PP |
| .Vb 1 |
| \& ld \-o <output> /lib/crt0.o hello.o \-lc |
| .Ve |
| .PP |
| This tells \fBld\fR to produce a file called \fIoutput\fR as the |
| result of linking the file \f(CW\*(C`/lib/crt0.o\*(C'\fR with \f(CW\*(C`hello.o\*(C'\fR and |
| the library \f(CW\*(C`libc.a\*(C'\fR, which will come from the standard search |
| directories. (See the discussion of the \fB\-l\fR option below.) |
| .PP |
| Some of the command-line options to \fBld\fR may be specified at any |
| point in the command line. However, options which refer to files, such |
| as \fB\-l\fR or \fB\-T\fR, cause the file to be read at the point at |
| which the option appears in the command line, relative to the object |
| files and other file options. Repeating non-file options with a |
| different argument will either have no further effect, or override prior |
| occurrences (those further to the left on the command line) of that |
| option. Options which may be meaningfully specified more than once are |
| noted in the descriptions below. |
| .PP |
| Non-option arguments are object files or archives which are to be linked |
| together. They may follow, precede, or be mixed in with command-line |
| options, except that an object file argument may not be placed between |
| an option and its argument. |
| .PP |
| Usually the linker is invoked with at least one object file, but you can |
| specify other forms of binary input files using \fB\-l\fR, \fB\-R\fR, |
| and the script command language. If \fIno\fR binary input files at all |
| are specified, the linker does not produce any output, and issues the |
| message \fBNo input files\fR. |
| .PP |
| If the linker cannot recognize the format of an object file, it will |
| assume that it is a linker script. A script specified in this way |
| augments the main linker script used for the link (either the default |
| linker script or the one specified by using \fB\-T\fR). This feature |
| permits the linker to link against a file which appears to be an object |
| or an archive, but actually merely defines some symbol values, or uses |
| \&\f(CW\*(C`INPUT\*(C'\fR or \f(CW\*(C`GROUP\*(C'\fR to load other objects. Specifying a |
| script in this way merely augments the main linker script, with the |
| extra commands placed after the main script; use the \fB\-T\fR option |
| to replace the default linker script entirely, but note the effect of |
| the \f(CW\*(C`INSERT\*(C'\fR command. |
| .PP |
| For options whose names are a single letter, |
| option arguments must either follow the option letter without intervening |
| whitespace, or be given as separate arguments immediately following the |
| option that requires them. |
| .PP |
| For options whose names are multiple letters, either one dash or two can |
| precede the option name; for example, \fB\-trace\-symbol\fR and |
| \&\fB\-\-trace\-symbol\fR are equivalent. Note\-\-\-there is one exception to |
| this rule. Multiple letter options that start with a lower case 'o' can |
| only be preceded by two dashes. This is to reduce confusion with the |
| \&\fB\-o\fR option. So for example \fB\-omagic\fR sets the output file |
| name to \fBmagic\fR whereas \fB\-\-omagic\fR sets the \s-1NMAGIC\s0 flag on the |
| output. |
| .PP |
| Arguments to multiple-letter options must either be separated from the |
| option name by an equals sign, or be given as separate arguments |
| immediately following the option that requires them. For example, |
| \&\fB\-\-trace\-symbol foo\fR and \fB\-\-trace\-symbol=foo\fR are equivalent. |
| Unique abbreviations of the names of multiple-letter options are |
| accepted. |
| .PP |
| Note\-\-\-if the linker is being invoked indirectly, via a compiler driver |
| (e.g. \fBgcc\fR) then all the linker command line options should be |
| prefixed by \fB\-Wl,\fR (or whatever is appropriate for the particular |
| compiler driver) like this: |
| .PP |
| .Vb 1 |
| \& gcc \-Wl,\-\-start\-group foo.o bar.o \-Wl,\-\-end\-group |
| .Ve |
| .PP |
| This is important, because otherwise the compiler driver program may |
| silently drop the linker options, resulting in a bad link. Confusion |
| may also arise when passing options that require values through a |
| driver, as the use of a space between option and argument acts as |
| a separator, and causes the driver to pass only the option to the linker |
| and the argument to the compiler. In this case, it is simplest to use |
| the joined forms of both single\- and multiple-letter options, such as: |
| .PP |
| .Vb 1 |
| \& gcc foo.o bar.o \-Wl,\-eENTRY \-Wl,\-Map=a.map |
| .Ve |
| .PP |
| Here is a table of the generic command line switches accepted by the \s-1GNU\s0 |
| linker: |
| .IP "\fB@\fR\fIfile\fR" 4 |
| .IX Item "@file" |
| Read command-line options from \fIfile\fR. The options read are |
| inserted in place of the original @\fIfile\fR option. If \fIfile\fR |
| does not exist, or cannot be read, then the option will be treated |
| literally, and not removed. |
| .Sp |
| Options in \fIfile\fR are separated by whitespace. A whitespace |
| character may be included in an option by surrounding the entire |
| option in either single or double quotes. Any character (including a |
| backslash) may be included by prefixing the character to be included |
| with a backslash. The \fIfile\fR may itself contain additional |
| @\fIfile\fR options; any such options will be processed recursively. |
| .IP "\fB\-a\fR \fIkeyword\fR" 4 |
| .IX Item "-a keyword" |
| This option is supported for \s-1HP/UX\s0 compatibility. The \fIkeyword\fR |
| argument must be one of the strings \fBarchive\fR, \fBshared\fR, or |
| \&\fBdefault\fR. \fB\-aarchive\fR is functionally equivalent to |
| \&\fB\-Bstatic\fR, and the other two keywords are functionally equivalent |
| to \fB\-Bdynamic\fR. This option may be used any number of times. |
| .IP "\fB\-\-audit\fR \fI\s-1AUDITLIB\s0\fR" 4 |
| .IX Item "--audit AUDITLIB" |
| Adds \fI\s-1AUDITLIB\s0\fR to the \f(CW\*(C`DT_AUDIT\*(C'\fR entry of the dynamic section. |
| \&\fI\s-1AUDITLIB\s0\fR is not checked for existence, nor will it use the \s-1DT_SONAME\s0 |
| specified in the library. If specified multiple times \f(CW\*(C`DT_AUDIT\*(C'\fR |
| will contain a colon separated list of audit interfaces to use. If the linker |
| finds an object with an audit entry while searching for shared libraries, |
| it will add a corresponding \f(CW\*(C`DT_DEPAUDIT\*(C'\fR entry in the output file. |
| This option is only meaningful on \s-1ELF\s0 platforms supporting the rtld-audit |
| interface. |
| .IP "\fB\-A\fR \fIarchitecture\fR" 4 |
| .IX Item "-A architecture" |
| .PD 0 |
| .IP "\fB\-\-architecture=\fR\fIarchitecture\fR" 4 |
| .IX Item "--architecture=architecture" |
| .PD |
| In the current release of \fBld\fR, this option is useful only for the |
| Intel 960 family of architectures. In that \fBld\fR configuration, the |
| \&\fIarchitecture\fR argument identifies the particular architecture in |
| the 960 family, enabling some safeguards and modifying the |
| archive-library search path. |
| .Sp |
| Future releases of \fBld\fR may support similar functionality for |
| other architecture families. |
| .IP "\fB\-b\fR \fIinput-format\fR" 4 |
| .IX Item "-b input-format" |
| .PD 0 |
| .IP "\fB\-\-format=\fR\fIinput-format\fR" 4 |
| .IX Item "--format=input-format" |
| .PD |
| \&\fBld\fR may be configured to support more than one kind of object |
| file. If your \fBld\fR is configured this way, you can use the |
| \&\fB\-b\fR option to specify the binary format for input object files |
| that follow this option on the command line. Even when \fBld\fR is |
| configured to support alternative object formats, you don't usually need |
| to specify this, as \fBld\fR should be configured to expect as a |
| default input format the most usual format on each machine. |
| \&\fIinput-format\fR is a text string, the name of a particular format |
| supported by the \s-1BFD\s0 libraries. (You can list the available binary |
| formats with \fBobjdump \-i\fR.) |
| .Sp |
| You may want to use this option if you are linking files with an unusual |
| binary format. You can also use \fB\-b\fR to switch formats explicitly (when |
| linking object files of different formats), by including |
| \&\fB\-b\fR \fIinput-format\fR before each group of object files in a |
| particular format. |
| .Sp |
| The default format is taken from the environment variable |
| \&\f(CW\*(C`GNUTARGET\*(C'\fR. |
| .Sp |
| You can also define the input format from a script, using the command |
| \&\f(CW\*(C`TARGET\*(C'\fR; |
| .IP "\fB\-c\fR \fIMRI-commandfile\fR" 4 |
| .IX Item "-c MRI-commandfile" |
| .PD 0 |
| .IP "\fB\-\-mri\-script=\fR\fIMRI-commandfile\fR" 4 |
| .IX Item "--mri-script=MRI-commandfile" |
| .PD |
| For compatibility with linkers produced by \s-1MRI\s0, \fBld\fR accepts script |
| files written in an alternate, restricted command language, described in |
| the \s-1MRI\s0 Compatible Script Files section of \s-1GNU\s0 ld documentation. |
| Introduce \s-1MRI\s0 script files with |
| the option \fB\-c\fR; use the \fB\-T\fR option to run linker |
| scripts written in the general-purpose \fBld\fR scripting language. |
| If \fIMRI-cmdfile\fR does not exist, \fBld\fR looks for it in the directories |
| specified by any \fB\-L\fR options. |
| .IP "\fB\-d\fR" 4 |
| .IX Item "-d" |
| .PD 0 |
| .IP "\fB\-dc\fR" 4 |
| .IX Item "-dc" |
| .IP "\fB\-dp\fR" 4 |
| .IX Item "-dp" |
| .PD |
| These three options are equivalent; multiple forms are supported for |
| compatibility with other linkers. They assign space to common symbols |
| even if a relocatable output file is specified (with \fB\-r\fR). The |
| script command \f(CW\*(C`FORCE_COMMON_ALLOCATION\*(C'\fR has the same effect. |
| .IP "\fB\-\-depaudit\fR \fI\s-1AUDITLIB\s0\fR" 4 |
| .IX Item "--depaudit AUDITLIB" |
| .PD 0 |
| .IP "\fB\-P\fR \fI\s-1AUDITLIB\s0\fR" 4 |
| .IX Item "-P AUDITLIB" |
| .PD |
| Adds \fI\s-1AUDITLIB\s0\fR to the \f(CW\*(C`DT_DEPAUDIT\*(C'\fR entry of the dynamic section. |
| \&\fI\s-1AUDITLIB\s0\fR is not checked for existence, nor will it use the \s-1DT_SONAME\s0 |
| specified in the library. If specified multiple times \f(CW\*(C`DT_DEPAUDIT\*(C'\fR |
| will contain a colon separated list of audit interfaces to use. This |
| option is only meaningful on \s-1ELF\s0 platforms supporting the rtld-audit interface. |
| The \-P option is provided for Solaris compatibility. |
| .IP "\fB\-e\fR \fIentry\fR" 4 |
| .IX Item "-e entry" |
| .PD 0 |
| .IP "\fB\-\-entry=\fR\fIentry\fR" 4 |
| .IX Item "--entry=entry" |
| .PD |
| Use \fIentry\fR as the explicit symbol for beginning execution of your |
| program, rather than the default entry point. If there is no symbol |
| named \fIentry\fR, the linker will try to parse \fIentry\fR as a number, |
| and use that as the entry address (the number will be interpreted in |
| base 10; you may use a leading \fB0x\fR for base 16, or a leading |
| \&\fB0\fR for base 8). |
| .IP "\fB\-\-exclude\-libs\fR \fIlib\fR\fB,\fR\fIlib\fR\fB,...\fR" 4 |
| .IX Item "--exclude-libs lib,lib,..." |
| Specifies a list of archive libraries from which symbols should not be automatically |
| exported. The library names may be delimited by commas or colons. Specifying |
| \&\f(CW\*(C`\-\-exclude\-libs ALL\*(C'\fR excludes symbols in all archive libraries from |
| automatic export. This option is available only for the i386 \s-1PE\s0 targeted |
| port of the linker and for \s-1ELF\s0 targeted ports. For i386 \s-1PE\s0, symbols |
| explicitly listed in a .def file are still exported, regardless of this |
| option. For \s-1ELF\s0 targeted ports, symbols affected by this option will |
| be treated as hidden. |
| .IP "\fB\-\-exclude\-modules\-for\-implib\fR \fImodule\fR\fB,\fR\fImodule\fR\fB,...\fR" 4 |
| .IX Item "--exclude-modules-for-implib module,module,..." |
| Specifies a list of object files or archive members, from which symbols |
| should not be automatically exported, but which should be copied wholesale |
| into the import library being generated during the link. The module names |
| may be delimited by commas or colons, and must match exactly the filenames |
| used by \fBld\fR to open the files; for archive members, this is simply |
| the member name, but for object files the name listed must include and |
| match precisely any path used to specify the input file on the linker's |
| command-line. This option is available only for the i386 \s-1PE\s0 targeted port |
| of the linker. Symbols explicitly listed in a .def file are still exported, |
| regardless of this option. |
| .IP "\fB\-E\fR" 4 |
| .IX Item "-E" |
| .PD 0 |
| .IP "\fB\-\-export\-dynamic\fR" 4 |
| .IX Item "--export-dynamic" |
| .IP "\fB\-\-no\-export\-dynamic\fR" 4 |
| .IX Item "--no-export-dynamic" |
| .PD |
| When creating a dynamically linked executable, using the \fB\-E\fR |
| option or the \fB\-\-export\-dynamic\fR option causes the linker to add |
| all symbols to the dynamic symbol table. The dynamic symbol table is the |
| set of symbols which are visible from dynamic objects at run time. |
| .Sp |
| If you do not use either of these options (or use the |
| \&\fB\-\-no\-export\-dynamic\fR option to restore the default behavior), the |
| dynamic symbol table will normally contain only those symbols which are |
| referenced by some dynamic object mentioned in the link. |
| .Sp |
| If you use \f(CW\*(C`dlopen\*(C'\fR to load a dynamic object which needs to refer |
| back to the symbols defined by the program, rather than some other |
| dynamic object, then you will probably need to use this option when |
| linking the program itself. |
| .Sp |
| You can also use the dynamic list to control what symbols should |
| be added to the dynamic symbol table if the output format supports it. |
| See the description of \fB\-\-dynamic\-list\fR. |
| .Sp |
| Note that this option is specific to \s-1ELF\s0 targeted ports. \s-1PE\s0 targets |
| support a similar function to export all symbols from a \s-1DLL\s0 or \s-1EXE\s0; see |
| the description of \fB\-\-export\-all\-symbols\fR below. |
| .IP "\fB\-EB\fR" 4 |
| .IX Item "-EB" |
| Link big-endian objects. This affects the default output format. |
| .IP "\fB\-EL\fR" 4 |
| .IX Item "-EL" |
| Link little-endian objects. This affects the default output format. |
| .IP "\fB\-f\fR \fIname\fR" 4 |
| .IX Item "-f name" |
| .PD 0 |
| .IP "\fB\-\-auxiliary=\fR\fIname\fR" 4 |
| .IX Item "--auxiliary=name" |
| .PD |
| When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_AUXILIARY\s0 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 \fIname\fR. |
| .Sp |
| If you later link a program against this filter object, then, when you |
| run the program, the dynamic linker will see the \s-1DT_AUXILIARY\s0 field. If |
| the dynamic linker resolves any symbols from the filter object, it will |
| first check whether there is a definition in the shared object |
| \&\fIname\fR. If there is one, it will be used instead of the definition |
| in the filter object. The shared object \fIname\fR need not exist. |
| Thus the shared object \fIname\fR may be used to provide an alternative |
| implementation of certain functions, perhaps for debugging or for |
| machine specific performance. |
| .Sp |
| This option may be specified more than once. The \s-1DT_AUXILIARY\s0 entries |
| will be created in the order in which they appear on the command line. |
| .IP "\fB\-F\fR \fIname\fR" 4 |
| .IX Item "-F name" |
| .PD 0 |
| .IP "\fB\-\-filter=\fR\fIname\fR" 4 |
| .IX Item "--filter=name" |
| .PD |
| When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_FILTER\s0 field to |
| the specified name. This tells the dynamic linker that the symbol table |
| of the shared object which is being created should be used as a filter |
| on the symbol table of the shared object \fIname\fR. |
| .Sp |
| If you later link a program against this filter object, then, when you |
| run the program, the dynamic linker will see the \s-1DT_FILTER\s0 field. The |
| dynamic linker will resolve symbols according to the symbol table of the |
| filter object as usual, but it will actually link to the definitions |
| found in the shared object \fIname\fR. Thus the filter object can be |
| used to select a subset of the symbols provided by the object |
| \&\fIname\fR. |
| .Sp |
| Some older linkers used the \fB\-F\fR option throughout a compilation |
| toolchain for specifying object-file format for both input and output |
| object files. |
| The \s-1GNU\s0 linker uses other mechanisms for this purpose: the |
| \&\fB\-b\fR, \fB\-\-format\fR, \fB\-\-oformat\fR options, the |
| \&\f(CW\*(C`TARGET\*(C'\fR command in linker scripts, and the \f(CW\*(C`GNUTARGET\*(C'\fR |
| environment variable. |
| The \s-1GNU\s0 linker will ignore the \fB\-F\fR option when not |
| creating an \s-1ELF\s0 shared object. |
| .IP "\fB\-fini=\fR\fIname\fR" 4 |
| .IX Item "-fini=name" |
| When creating an \s-1ELF\s0 executable or shared object, call \s-1NAME\s0 when the |
| executable or shared object is unloaded, by setting \s-1DT_FINI\s0 to the |
| address of the function. By default, the linker uses \f(CW\*(C`_fini\*(C'\fR as |
| the function to call. |
| .IP "\fB\-g\fR" 4 |
| .IX Item "-g" |
| Ignored. Provided for compatibility with other tools. |
| .IP "\fB\-G\fR \fIvalue\fR" 4 |
| .IX Item "-G value" |
| .PD 0 |
| .IP "\fB\-\-gpsize=\fR\fIvalue\fR" 4 |
| .IX Item "--gpsize=value" |
| .PD |
| Set the maximum size of objects to be optimized using the \s-1GP\s0 register to |
| \&\fIsize\fR. This is only meaningful for object file formats such as |
| \&\s-1MIPS\s0 \s-1ECOFF\s0 which supports putting large and small objects into different |
| sections. This is ignored for other object file formats. |
| .IP "\fB\-h\fR \fIname\fR" 4 |
| .IX Item "-h name" |
| .PD 0 |
| .IP "\fB\-soname=\fR\fIname\fR" 4 |
| .IX Item "-soname=name" |
| .PD |
| When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_SONAME\s0 field to |
| the specified name. When an executable is linked with a shared object |
| which has a \s-1DT_SONAME\s0 field, then when the executable is run the dynamic |
| linker will attempt to load the shared object specified by the \s-1DT_SONAME\s0 |
| field rather than the using the file name given to the linker. |
| .IP "\fB\-i\fR" 4 |
| .IX Item "-i" |
| Perform an incremental link (same as option \fB\-r\fR). |
| .IP "\fB\-init=\fR\fIname\fR" 4 |
| .IX Item "-init=name" |
| When creating an \s-1ELF\s0 executable or shared object, call \s-1NAME\s0 when the |
| executable or shared object is loaded, by setting \s-1DT_INIT\s0 to the address |
| of the function. By default, the linker uses \f(CW\*(C`_init\*(C'\fR as the |
| function to call. |
| .IP "\fB\-l\fR \fInamespec\fR" 4 |
| .IX Item "-l namespec" |
| .PD 0 |
| .IP "\fB\-\-library=\fR\fInamespec\fR" 4 |
| .IX Item "--library=namespec" |
| .PD |
| Add the archive or object file specified by \fInamespec\fR to the |
| list of files to link. This option may be used any number of times. |
| If \fInamespec\fR is of the form \fI:\fIfilename\fI\fR, \fBld\fR |
| will search the library path for a file called \fIfilename\fR, otherwise it |
| will search the library path for a file called \fIlib\fInamespec\fI.a\fR. |
| .Sp |
| On systems which support shared libraries, \fBld\fR may also search for |
| files other than \fIlib\fInamespec\fI.a\fR. Specifically, on \s-1ELF\s0 |
| and SunOS systems, \fBld\fR will search a directory for a library |
| called \fIlib\fInamespec\fI.so\fR before searching for one called |
| \&\fIlib\fInamespec\fI.a\fR. (By convention, a \f(CW\*(C`.so\*(C'\fR extension |
| indicates a shared library.) Note that this behavior does not apply |
| to \fI:\fIfilename\fI\fR, which always specifies a file called |
| \&\fIfilename\fR. |
| .Sp |
| The linker will search an archive only once, at the location where it is |
| specified on the command line. If the archive defines a symbol which |
| was undefined in some object which appeared before the archive on the |
| command line, the linker will include the appropriate file(s) from the |
| archive. However, an undefined symbol in an object appearing later on |
| the command line will not cause the linker to search the archive again. |
| .Sp |
| See the \fB\-(\fR option for a way to force the linker to search |
| archives multiple times. |
| .Sp |
| You may list the same archive multiple times on the command line. |
| .Sp |
| This type of archive searching is standard for Unix linkers. However, |
| if you are using \fBld\fR on \s-1AIX\s0, note that it is different from the |
| behaviour of the \s-1AIX\s0 linker. |
| .IP "\fB\-L\fR \fIsearchdir\fR" 4 |
| .IX Item "-L searchdir" |
| .PD 0 |
| .IP "\fB\-\-library\-path=\fR\fIsearchdir\fR" 4 |
| .IX Item "--library-path=searchdir" |
| .PD |
| Add path \fIsearchdir\fR to the list of paths that \fBld\fR will search |
| for archive libraries and \fBld\fR control scripts. You may use this |
| option any number of times. The directories are searched in the order |
| in which they are specified on the command line. Directories specified |
| on the command line are searched before the default directories. All |
| \&\fB\-L\fR options apply to all \fB\-l\fR options, regardless of the |
| order in which the options appear. \fB\-L\fR options do not affect |
| how \fBld\fR searches for a linker script unless \fB\-T\fR |
| option is specified. |
| .Sp |
| If \fIsearchdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced |
| by the \fIsysroot prefix\fR, a path specified when the linker is configured. |
| .Sp |
| The default set of paths searched (without being specified with |
| \&\fB\-L\fR) depends on which emulation mode \fBld\fR is using, and in |
| some cases also on how it was configured. |
| .Sp |
| The paths can also be specified in a link script with the |
| \&\f(CW\*(C`SEARCH_DIR\*(C'\fR command. Directories specified this way are searched |
| at the point in which the linker script appears in the command line. |
| .IP "\fB\-m\fR \fIemulation\fR" 4 |
| .IX Item "-m emulation" |
| Emulate the \fIemulation\fR linker. You can list the available |
| emulations with the \fB\-\-verbose\fR or \fB\-V\fR options. |
| .Sp |
| If the \fB\-m\fR option is not used, the emulation is taken from the |
| \&\f(CW\*(C`LDEMULATION\*(C'\fR environment variable, if that is defined. |
| .Sp |
| Otherwise, the default emulation depends upon how the linker was |
| configured. |
| .IP "\fB\-M\fR" 4 |
| .IX Item "-M" |
| .PD 0 |
| .IP "\fB\-\-print\-map\fR" 4 |
| .IX Item "--print-map" |
| .PD |
| Print a link map to the standard output. A link map provides |
| information about the link, including the following: |
| .RS 4 |
| .IP "\(bu" 4 |
| Where object files are mapped into memory. |
| .IP "\(bu" 4 |
| How common symbols are allocated. |
| .IP "\(bu" 4 |
| All archive members included in the link, with a mention of the symbol |
| which caused the archive member to be brought in. |
| .IP "\(bu" 4 |
| The values assigned to symbols. |
| .Sp |
| Note \- symbols whose values are computed by an expression which |
| involves a reference to a previous value of the same symbol may not |
| have correct result displayed in the link map. This is because the |
| linker discards intermediate results and only retains the final value |
| of an expression. Under such circumstances the linker will display |
| the final value enclosed by square brackets. Thus for example a |
| linker script containing: |
| .Sp |
| .Vb 3 |
| \& foo = 1 |
| \& foo = foo * 4 |
| \& foo = foo + 8 |
| .Ve |
| .Sp |
| will produce the following output in the link map if the \fB\-M\fR |
| option is used: |
| .Sp |
| .Vb 3 |
| \& 0x00000001 foo = 0x1 |
| \& [0x0000000c] foo = (foo * 0x4) |
| \& [0x0000000c] foo = (foo + 0x8) |
| .Ve |
| .Sp |
| See \fBExpressions\fR for more information about expressions in linker |
| scripts. |
| .RE |
| .RS 4 |
| .RE |
| .IP "\fB\-n\fR" 4 |
| .IX Item "-n" |
| .PD 0 |
| .IP "\fB\-\-nmagic\fR" 4 |
| .IX Item "--nmagic" |
| .PD |
| Turn off page alignment of sections, and disable linking against shared |
| libraries. If the output format supports Unix style magic numbers, |
| mark the output as \f(CW\*(C`NMAGIC\*(C'\fR. |
| .IP "\fB\-N\fR" 4 |
| .IX Item "-N" |
| .PD 0 |
| .IP "\fB\-\-omagic\fR" 4 |
| .IX Item "--omagic" |
| .PD |
| Set the text and data sections to be readable and writable. Also, do |
| not page-align the data segment, and disable linking against shared |
| libraries. If the output format supports Unix style magic numbers, |
| mark the output as \f(CW\*(C`OMAGIC\*(C'\fR. Note: Although a writable text section |
| is allowed for PE-COFF targets, it does not conform to the format |
| specification published by Microsoft. |
| .IP "\fB\-\-no\-omagic\fR" 4 |
| .IX Item "--no-omagic" |
| This option negates most of the effects of the \fB\-N\fR option. It |
| sets the text section to be read-only, and forces the data segment to |
| be page-aligned. Note \- this option does not enable linking against |
| shared libraries. Use \fB\-Bdynamic\fR for this. |
| .IP "\fB\-o\fR \fIoutput\fR" 4 |
| .IX Item "-o output" |
| .PD 0 |
| .IP "\fB\-\-output=\fR\fIoutput\fR" 4 |
| .IX Item "--output=output" |
| .PD |
| Use \fIoutput\fR as the name for the program produced by \fBld\fR; if this |
| option is not specified, the name \fIa.out\fR is used by default. The |
| script command \f(CW\*(C`OUTPUT\*(C'\fR can also specify the output file name. |
| .IP "\fB\-O\fR \fIlevel\fR" 4 |
| .IX Item "-O level" |
| If \fIlevel\fR is a numeric values greater than zero \fBld\fR optimizes |
| the output. This might take significantly longer and therefore probably |
| should only be enabled for the final binary. At the moment this |
| option only affects \s-1ELF\s0 shared library generation. Future releases of |
| the linker may make more use of this option. Also currently there is |
| no difference in the linker's behaviour for different non-zero values |
| of this option. Again this may change with future releases. |
| .IP "\fB\-q\fR" 4 |
| .IX Item "-q" |
| .PD 0 |
| .IP "\fB\-\-emit\-relocs\fR" 4 |
| .IX Item "--emit-relocs" |
| .PD |
| Leave relocation sections and contents in fully linked executables. |
| Post link analysis and optimization tools may need this information in |
| order to perform correct modifications of executables. This results |
| in larger executables. |
| .Sp |
| This option is currently only supported on \s-1ELF\s0 platforms. |
| .IP "\fB\-\-force\-dynamic\fR" 4 |
| .IX Item "--force-dynamic" |
| Force the output file to have dynamic sections. This option is specific |
| to VxWorks targets. |
| .IP "\fB\-r\fR" 4 |
| .IX Item "-r" |
| .PD 0 |
| .IP "\fB\-\-relocatable\fR" 4 |
| .IX Item "--relocatable" |
| .PD |
| Generate relocatable output\-\-\-i.e., generate an output file that can in |
| turn serve as input to \fBld\fR. This is often called \fIpartial |
| linking\fR. As a side effect, in environments that support standard Unix |
| magic numbers, this option also sets the output file's magic number to |
| \&\f(CW\*(C`OMAGIC\*(C'\fR. |
| If this option is not specified, an absolute file is produced. When |
| linking \*(C+ programs, this option \fIwill not\fR resolve references to |
| constructors; to do that, use \fB\-Ur\fR. |
| .Sp |
| When an input file does not have the same format as the output file, |
| partial linking is only supported if that input file does not contain any |
| relocations. Different output formats can have further restrictions; for |
| example some \f(CW\*(C`a.out\*(C'\fR\-based formats do not support partial linking |
| with input files in other formats at all. |
| .Sp |
| This option does the same thing as \fB\-i\fR. |
| .IP "\fB\-R\fR \fIfilename\fR" 4 |
| .IX Item "-R filename" |
| .PD 0 |
| .IP "\fB\-\-just\-symbols=\fR\fIfilename\fR" 4 |
| .IX Item "--just-symbols=filename" |
| .PD |
| Read symbol names and their addresses from \fIfilename\fR, 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. You may use this option more than once. |
| .Sp |
| For compatibility with other \s-1ELF\s0 linkers, if the \fB\-R\fR option is |
| followed by a directory name, rather than a file name, it is treated as |
| the \fB\-rpath\fR option. |
| .IP "\fB\-s\fR" 4 |
| .IX Item "-s" |
| .PD 0 |
| .IP "\fB\-\-strip\-all\fR" 4 |
| .IX Item "--strip-all" |
| .PD |
| Omit all symbol information from the output file. |
| .IP "\fB\-S\fR" 4 |
| .IX Item "-S" |
| .PD 0 |
| .IP "\fB\-\-strip\-debug\fR" 4 |
| .IX Item "--strip-debug" |
| .PD |
| Omit debugger symbol information (but not all symbols) from the output file. |
| .IP "\fB\-t\fR" 4 |
| .IX Item "-t" |
| .PD 0 |
| .IP "\fB\-\-trace\fR" 4 |
| .IX Item "--trace" |
| .PD |
| Print the names of the input files as \fBld\fR processes them. |
| .IP "\fB\-T\fR \fIscriptfile\fR" 4 |
| .IX Item "-T scriptfile" |
| .PD 0 |
| .IP "\fB\-\-script=\fR\fIscriptfile\fR" 4 |
| .IX Item "--script=scriptfile" |
| .PD |
| Use \fIscriptfile\fR as the linker script. This script replaces |
| \&\fBld\fR's default linker script (rather than adding to it), so |
| \&\fIcommandfile\fR must specify everything necessary to describe the |
| output file. If \fIscriptfile\fR does not exist in |
| the current directory, \f(CW\*(C`ld\*(C'\fR looks for it in the directories |
| specified by any preceding \fB\-L\fR options. Multiple \fB\-T\fR |
| options accumulate. |
| .IP "\fB\-dT\fR \fIscriptfile\fR" 4 |
| .IX Item "-dT scriptfile" |
| .PD 0 |
| .IP "\fB\-\-default\-script=\fR\fIscriptfile\fR" 4 |
| .IX Item "--default-script=scriptfile" |
| .PD |
| Use \fIscriptfile\fR as the default linker script. |
| .Sp |
| This option is similar to the \fB\-\-script\fR option except that |
| processing of the script is delayed until after the rest of the |
| command line has been processed. This allows options placed after the |
| \&\fB\-\-default\-script\fR option on the command line to affect the |
| behaviour of the linker script, which can be important when the linker |
| command line cannot be directly controlled by the user. (eg because |
| the command line is being constructed by another tool, such as |
| \&\fBgcc\fR). |
| .IP "\fB\-u\fR \fIsymbol\fR" 4 |
| .IX Item "-u symbol" |
| .PD 0 |
| .IP "\fB\-\-undefined=\fR\fIsymbol\fR" 4 |
| .IX Item "--undefined=symbol" |
| .PD |
| Force \fIsymbol\fR to be entered in the output file as an undefined |
| symbol. Doing this may, for example, trigger linking of additional |
| modules from standard libraries. \fB\-u\fR may be repeated with |
| different option arguments to enter additional undefined symbols. This |
| option is equivalent to the \f(CW\*(C`EXTERN\*(C'\fR linker script command. |
| .IP "\fB\-Ur\fR" 4 |
| .IX Item "-Ur" |
| For anything other than \*(C+ programs, this option is equivalent to |
| \&\fB\-r\fR: it generates relocatable output\-\-\-i.e., an output file that can in |
| turn serve as input to \fBld\fR. When linking \*(C+ programs, \fB\-Ur\fR |
| \&\fIdoes\fR resolve references to constructors, unlike \fB\-r\fR. |
| It does not work to use \fB\-Ur\fR on files that were themselves linked |
| with \fB\-Ur\fR; once the constructor table has been built, it cannot |
| be added to. Use \fB\-Ur\fR only for the last partial link, and |
| \&\fB\-r\fR for the others. |
| .IP "\fB\-\-unique[=\fR\fI\s-1SECTION\s0\fR\fB]\fR" 4 |
| .IX Item "--unique[=SECTION]" |
| Creates a separate output section for every input section matching |
| \&\fI\s-1SECTION\s0\fR, or if the optional wildcard \fI\s-1SECTION\s0\fR argument is |
| missing, for every orphan input section. An orphan section is one not |
| specifically mentioned in a linker script. You may use this option |
| multiple times on the command line; It prevents the normal merging of |
| input sections with the same name, overriding output section assignments |
| in a linker script. |
| .IP "\fB\-v\fR" 4 |
| .IX Item "-v" |
| .PD 0 |
| .IP "\fB\-\-version\fR" 4 |
| .IX Item "--version" |
| .IP "\fB\-V\fR" 4 |
| .IX Item "-V" |
| .PD |
| Display the version number for \fBld\fR. The \fB\-V\fR option also |
| lists the supported emulations. |
| .IP "\fB\-x\fR" 4 |
| .IX Item "-x" |
| .PD 0 |
| .IP "\fB\-\-discard\-all\fR" 4 |
| .IX Item "--discard-all" |
| .PD |
| Delete all local symbols. |
| .IP "\fB\-X\fR" 4 |
| .IX Item "-X" |
| .PD 0 |
| .IP "\fB\-\-discard\-locals\fR" 4 |
| .IX Item "--discard-locals" |
| .PD |
| Delete all temporary local symbols. (These symbols start with |
| system-specific local label prefixes, typically \fB.L\fR for \s-1ELF\s0 systems |
| or \fBL\fR for traditional a.out systems.) |
| .IP "\fB\-y\fR \fIsymbol\fR" 4 |
| .IX Item "-y symbol" |
| .PD 0 |
| .IP "\fB\-\-trace\-symbol=\fR\fIsymbol\fR" 4 |
| .IX Item "--trace-symbol=symbol" |
| .PD |
| Print the name of each linked file in which \fIsymbol\fR appears. This |
| option may be given any number of times. On many systems it is necessary |
| to prepend an underscore. |
| .Sp |
| This option is useful when you have an undefined symbol in your link but |
| don't know where the reference is coming from. |
| .IP "\fB\-Y\fR \fIpath\fR" 4 |
| .IX Item "-Y path" |
| Add \fIpath\fR to the default library search path. This option exists |
| for Solaris compatibility. |
| .IP "\fB\-z\fR \fIkeyword\fR" 4 |
| .IX Item "-z keyword" |
| The recognized keywords are: |
| .RS 4 |
| .IP "\fBcombreloc\fR" 4 |
| .IX Item "combreloc" |
| Combines multiple reloc sections and sorts them to make dynamic symbol |
| lookup caching possible. |
| .IP "\fBdefs\fR" 4 |
| .IX Item "defs" |
| Disallows undefined symbols in object files. Undefined symbols in |
| shared libraries are still allowed. |
| .IP "\fBexecstack\fR" 4 |
| .IX Item "execstack" |
| Marks the object as requiring executable stack. |
| .IP "\fBglobal\fR" 4 |
| .IX Item "global" |
| This option is only meaningful when building a shared object. It makes |
| the symbols defined by this shared object available for symbol resolution |
| of subsequently loaded libraries. |
| .IP "\fBinitfirst\fR" 4 |
| .IX Item "initfirst" |
| This option is only meaningful when building a shared object. |
| It marks the object so that its runtime initialization will occur |
| before the runtime initialization of any other objects brought into |
| the process at the same time. Similarly the runtime finalization of |
| the object will occur after the runtime finalization of any other |
| objects. |
| .IP "\fBinterpose\fR" 4 |
| .IX Item "interpose" |
| Marks the object that its symbol table interposes before all symbols |
| but the primary executable. |
| .IP "\fBlazy\fR" 4 |
| .IX Item "lazy" |
| When generating an executable or shared library, mark it to tell the |
| dynamic linker to defer function call resolution to the point when |
| the function is called (lazy binding), rather than at load time. |
| Lazy binding is the default. |
| .IP "\fBloadfltr\fR" 4 |
| .IX Item "loadfltr" |
| Marks the object that its filters be processed immediately at |
| runtime. |
| .IP "\fBmuldefs\fR" 4 |
| .IX Item "muldefs" |
| Allows multiple definitions. |
| .IP "\fBnocombreloc\fR" 4 |
| .IX Item "nocombreloc" |
| Disables multiple reloc sections combining. |
| .IP "\fBnocopyreloc\fR" 4 |
| .IX Item "nocopyreloc" |
| Disables production of copy relocs. |
| .IP "\fBnodefaultlib\fR" 4 |
| .IX Item "nodefaultlib" |
| Marks the object that the search for dependencies of this object will |
| ignore any default library search paths. |
| .IP "\fBnodelete\fR" 4 |
| .IX Item "nodelete" |
| Marks the object shouldn't be unloaded at runtime. |
| .IP "\fBnodlopen\fR" 4 |
| .IX Item "nodlopen" |
| Marks the object not available to \f(CW\*(C`dlopen\*(C'\fR. |
| .IP "\fBnodump\fR" 4 |
| .IX Item "nodump" |
| Marks the object can not be dumped by \f(CW\*(C`dldump\*(C'\fR. |
| .IP "\fBnoexecstack\fR" 4 |
| .IX Item "noexecstack" |
| Marks the object as not requiring executable stack. |
| .IP "\fBnorelro\fR" 4 |
| .IX Item "norelro" |
| Don't create an \s-1ELF\s0 \f(CW\*(C`PT_GNU_RELRO\*(C'\fR segment header in the object. |
| .IP "\fBnow\fR" 4 |
| .IX Item "now" |
| When generating an executable or shared library, mark it to tell the |
| dynamic linker to resolve all symbols when the program is started, or |
| when the shared library is linked to using dlopen, instead of |
| deferring function call resolution to the point when the function is |
| first called. |
| .IP "\fBorigin\fR" 4 |
| .IX Item "origin" |
| Marks the object may contain \f(CW$ORIGIN\fR. |
| .IP "\fBrelro\fR" 4 |
| .IX Item "relro" |
| Create an \s-1ELF\s0 \f(CW\*(C`PT_GNU_RELRO\*(C'\fR segment header in the object. |
| .IP "\fBnosecondary\fR" 4 |
| .IX Item "nosecondary" |
| Convert secondary symbols to weak symbols when generating a shared |
| library. |
| .IP "\fBmax\-page\-size=\fR\fIvalue\fR" 4 |
| .IX Item "max-page-size=value" |
| Set the emulation maximum page size to \fIvalue\fR. |
| .IP "\fBcommon\-page\-size=\fR\fIvalue\fR" 4 |
| .IX Item "common-page-size=value" |
| Set the emulation common page size to \fIvalue\fR. |
| .IP "\fBstack\-size=\fR\fIvalue\fR" 4 |
| .IX Item "stack-size=value" |
| Specify a stack size for in an \s-1ELF\s0 \f(CW\*(C`PT_GNU_STACK\*(C'\fR segment. |
| Specifying zero will override any default non-zero sized |
| \&\f(CW\*(C`PT_GNU_STACK\*(C'\fR segment creation. |
| .RE |
| .RS 4 |
| .Sp |
| Other keywords are ignored for Solaris compatibility. |
| .RE |
| .IP "\fB\-(\fR \fIarchives\fR \fB\-)\fR" 4 |
| .IX Item "-( archives -)" |
| .PD 0 |
| .IP "\fB\-\-start\-group\fR \fIarchives\fR \fB\-\-end\-group\fR" 4 |
| .IX Item "--start-group archives --end-group" |
| .PD |
| The \fIarchives\fR should be a list of archive files. They may be |
| either explicit file names, or \fB\-l\fR options. |
| .Sp |
| The specified archives are searched repeatedly until no new undefined |
| references are created. Normally, an archive is searched only once in |
| the order that it is specified on the command line. If a symbol in that |
| archive is needed to resolve an undefined symbol referred to by an |
| object in an archive that appears later on the command line, the linker |
| would not be able to resolve that reference. By grouping the archives, |
| they all be searched repeatedly until all possible references are |
| resolved. |
| .Sp |
| Using this option has a significant performance cost. It is best to use |
| it only when there are unavoidable circular references between two or |
| more archives. |
| .IP "\fB\-\-accept\-unknown\-input\-arch\fR" 4 |
| .IX Item "--accept-unknown-input-arch" |
| .PD 0 |
| .IP "\fB\-\-no\-accept\-unknown\-input\-arch\fR" 4 |
| .IX Item "--no-accept-unknown-input-arch" |
| .PD |
| Tells the linker to accept input files whose architecture cannot be |
| recognised. The assumption is that the user knows what they are doing |
| and deliberately wants to link in these unknown input files. This was |
| the default behaviour of the linker, before release 2.14. The default |
| behaviour from release 2.14 onwards is to reject such input files, and |
| so the \fB\-\-accept\-unknown\-input\-arch\fR option has been added to |
| restore the old behaviour. |
| .IP "\fB\-\-as\-needed\fR" 4 |
| .IX Item "--as-needed" |
| .PD 0 |
| .IP "\fB\-\-no\-as\-needed\fR" 4 |
| .IX Item "--no-as-needed" |
| .PD |
| This option affects \s-1ELF\s0 \s-1DT_NEEDED\s0 tags for dynamic libraries mentioned |
| on the command line after the \fB\-\-as\-needed\fR option. Normally |
| the linker will add a \s-1DT_NEEDED\s0 tag for each dynamic library mentioned |
| on the command line, regardless of whether the library is actually |
| needed or not. \fB\-\-as\-needed\fR causes a \s-1DT_NEEDED\s0 tag to only be |
| emitted for a library that \fIat that point in the link\fR satisfies a |
| non-weak undefined symbol reference from a regular object file or, if |
| the library is not found in the \s-1DT_NEEDED\s0 lists of other libraries, a |
| non-weak undefined symbol reference from another dynamic library. |
| Object files or libraries appearing on the command line \fIafter\fR |
| the library in question do not affect whether the library is seen as |
| needed. This is similar to the rules for extraction of object files |
| from archives. \fB\-\-no\-as\-needed\fR restores the default behaviour. |
| .IP "\fB\-\-add\-needed\fR" 4 |
| .IX Item "--add-needed" |
| .PD 0 |
| .IP "\fB\-\-no\-add\-needed\fR" 4 |
| .IX Item "--no-add-needed" |
| .PD |
| These two options have been deprecated because of the similarity of |
| their names to the \fB\-\-as\-needed\fR and \fB\-\-no\-as\-needed\fR |
| options. They have been replaced by \fB\-\-copy\-dt\-needed\-entries\fR |
| and \fB\-\-no\-copy\-dt\-needed\-entries\fR. |
| .IP "\fB\-assert\fR \fIkeyword\fR" 4 |
| .IX Item "-assert keyword" |
| This option is ignored for SunOS compatibility. |
| .IP "\fB\-Bdynamic\fR" 4 |
| .IX Item "-Bdynamic" |
| .PD 0 |
| .IP "\fB\-dy\fR" 4 |
| .IX Item "-dy" |
| .IP "\fB\-call_shared\fR" 4 |
| .IX Item "-call_shared" |
| .PD |
| 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. The different variants of this option are |
| for compatibility with various systems. You may use this option |
| multiple times on the command line: it affects library searching for |
| \&\fB\-l\fR options which follow it. |
| .IP "\fB\-Bgroup\fR" 4 |
| .IX Item "-Bgroup" |
| Set the \f(CW\*(C`DF_1_GROUP\*(C'\fR flag in the \f(CW\*(C`DT_FLAGS_1\*(C'\fR entry in the dynamic |
| section. This causes the runtime linker to handle lookups in this |
| object and its dependencies to be performed only inside the group. |
| \&\fB\-\-unresolved\-symbols=report\-all\fR is implied. This option is |
| only meaningful on \s-1ELF\s0 platforms which support shared libraries. |
| .IP "\fB\-Bstatic\fR" 4 |
| .IX Item "-Bstatic" |
| .PD 0 |
| .IP "\fB\-dn\fR" 4 |
| .IX Item "-dn" |
| .IP "\fB\-non_shared\fR" 4 |
| .IX Item "-non_shared" |
| .IP "\fB\-static\fR" 4 |
| .IX Item "-static" |
| .PD |
| Do not link against shared libraries. This is only meaningful on |
| platforms for which shared libraries are supported. The different |
| variants of this option are for compatibility with various systems. You |
| may use this option multiple times on the command line: it affects |
| library searching for \fB\-l\fR options which follow it. This |
| option also implies \fB\-\-unresolved\-symbols=report\-all\fR. This |
| option can be used with \fB\-shared\fR. Doing so means that a |
| shared library is being created but that all of the library's external |
| references must be resolved by pulling in entries from static |
| libraries. |
| .IP "\fB\-Bsymbolic\fR" 4 |
| .IX Item "-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 \s-1ELF\s0 |
| platforms which support shared libraries. |
| .IP "\fB\-Bsymbolic\-functions\fR" 4 |
| .IX Item "-Bsymbolic-functions" |
| When creating a shared library, bind references to global function |
| symbols to the definition within the shared library, if any. |
| This option is only meaningful on \s-1ELF\s0 platforms which support shared |
| libraries. |
| .IP "\fB\-\-dynamic\-list=\fR\fIdynamic-list-file\fR" 4 |
| .IX Item "--dynamic-list=dynamic-list-file" |
| Specify the name of a dynamic list file to the linker. This is |
| typically used when creating shared libraries to specify a list of |
| global symbols whose references shouldn't be bound to the definition |
| within the shared library, or creating dynamically linked executables |
| to specify a list of symbols which should be added to the symbol table |
| in the executable. This option is only meaningful on \s-1ELF\s0 platforms |
| which support shared libraries. |
| .Sp |
| The format of the dynamic list is the same as the version node without |
| scope and node name. See \fB\s-1VERSION\s0\fR for more information. |
| .IP "\fB\-\-dynamic\-list\-data\fR" 4 |
| .IX Item "--dynamic-list-data" |
| Include all global data symbols to the dynamic list. |
| .IP "\fB\-\-dynamic\-list\-cpp\-new\fR" 4 |
| .IX Item "--dynamic-list-cpp-new" |
| Provide the builtin dynamic list for \*(C+ operator new and delete. It |
| is mainly useful for building shared libstdc++. |
| .IP "\fB\-\-dynamic\-list\-cpp\-typeinfo\fR" 4 |
| .IX Item "--dynamic-list-cpp-typeinfo" |
| Provide the builtin dynamic list for \*(C+ runtime type identification. |
| .IP "\fB\-\-check\-sections\fR" 4 |
| .IX Item "--check-sections" |
| .PD 0 |
| .IP "\fB\-\-no\-check\-sections\fR" 4 |
| .IX Item "--no-check-sections" |
| .PD |
| Asks the linker \fInot\fR to check section addresses after they have |
| been assigned to see if there are any overlaps. Normally the linker will |
| perform this check, and if it finds any overlaps it will produce |
| suitable error messages. The linker does know about, and does make |
| allowances for sections in overlays. The default behaviour can be |
| restored by using the command line switch \fB\-\-check\-sections\fR. |
| Section overlap is not usually checked for relocatable links. You can |
| force checking in that case by using the \fB\-\-check\-sections\fR |
| option. |
| .IP "\fB\-\-copy\-dt\-needed\-entries\fR" 4 |
| .IX Item "--copy-dt-needed-entries" |
| .PD 0 |
| .IP "\fB\-\-no\-copy\-dt\-needed\-entries\fR" 4 |
| .IX Item "--no-copy-dt-needed-entries" |
| .PD |
| This option affects the treatment of dynamic libraries referred to |
| by \s-1DT_NEEDED\s0 tags \fIinside\fR \s-1ELF\s0 dynamic libraries mentioned on the |
| command line. Normally the linker won't add a \s-1DT_NEEDED\s0 tag to the |
| output binary for each library mentioned in a \s-1DT_NEEDED\s0 tag in an |
| input dynamic library. With \fB\-\-copy\-dt\-needed\-entries\fR |
| specified on the command line however any dynamic libraries that |
| follow it will have their \s-1DT_NEEDED\s0 entries added. The default |
| behaviour can be restored with \fB\-\-no\-copy\-dt\-needed\-entries\fR. |
| .Sp |
| This option also has an effect on the resolution of symbols in dynamic |
| libraries. With \fB\-\-copy\-dt\-needed\-entries\fR dynamic libraries |
| mentioned on the command line will be recursively searched, following |
| their \s-1DT_NEEDED\s0 tags to other libraries, in order to resolve symbols |
| required by the output binary. With the default setting however |
| the searching of dynamic libraries that follow it will stop with the |
| dynamic library itself. No \s-1DT_NEEDED\s0 links will be traversed to resolve |
| symbols. |
| .IP "\fB\-\-cref\fR" 4 |
| .IX Item "--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. |
| .Sp |
| The format of the table is intentionally simple, so that it may be |
| easily processed by a script if necessary. The symbols are printed out, |
| sorted by name. For each symbol, a list of file names is given. If the |
| symbol is defined, the first file listed is the location of the |
| definition. The remaining files contain references to the symbol. |
| .IP "\fB\-\-no\-define\-common\fR" 4 |
| .IX Item "--no-define-common" |
| This option inhibits the assignment of addresses to common symbols. |
| The script command \f(CW\*(C`INHIBIT_COMMON_ALLOCATION\*(C'\fR has the same effect. |
| .Sp |
| The \fB\-\-no\-define\-common\fR option allows decoupling |
| the decision to assign addresses to Common symbols from the choice |
| of the output file type; otherwise a non-Relocatable output type |
| forces assigning addresses to Common symbols. |
| Using \fB\-\-no\-define\-common\fR allows Common symbols that are referenced |
| from a shared library to be assigned addresses only in the main program. |
| This eliminates the unused duplicate space in the shared library, |
| and also prevents any possible confusion over resolving to the wrong |
| duplicate when there are many dynamic modules with specialized search |
| paths for runtime symbol resolution. |
| .IP "\fB\-\-defsym=\fR\fIsymbol\fR\fB=\fR\fIexpression\fR" 4 |
| .IX Item "--defsym=symbol=expression" |
| Create a global symbol in the output file, containing the absolute |
| address given by \fIexpression\fR. 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 \fIexpression\fR in this |
| context: you may give a hexadecimal constant or the name of an existing |
| symbol, or use \f(CW\*(C`+\*(C'\fR and \f(CW\*(C`\-\*(C'\fR to add or subtract hexadecimal |
| constants or symbols. If you need more elaborate expressions, consider |
| using the linker command language from a script. \fINote:\fR there should be no white |
| space between \fIsymbol\fR, the equals sign ("\fB=\fR"), and |
| \&\fIexpression\fR. |
| .IP "\fB\-\-demangle[=\fR\fIstyle\fR\fB]\fR" 4 |
| .IX Item "--demangle[=style]" |
| .PD 0 |
| .IP "\fB\-\-no\-demangle\fR" 4 |
| .IX Item "--no-demangle" |
| .PD |
| 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. Different compilers have |
| different mangling styles. The optional demangling style argument can be used |
| to choose an appropriate demangling style for your compiler. The linker will |
| demangle by default unless the environment variable \fB\s-1COLLECT_NO_DEMANGLE\s0\fR |
| is set. These options may be used to override the default. |
| .IP "\fB\-I\fR\fIfile\fR" 4 |
| .IX Item "-Ifile" |
| .PD 0 |
| .IP "\fB\-\-dynamic\-linker=\fR\fIfile\fR" 4 |
| .IX Item "--dynamic-linker=file" |
| .PD |
| Set the name of the dynamic linker. This is only meaningful when |
| generating dynamically linked \s-1ELF\s0 executables. The default dynamic |
| linker is normally correct; don't use this unless you know what you are |
| doing. |
| .IP "\fB\-\-fatal\-warnings\fR" 4 |
| .IX Item "--fatal-warnings" |
| .PD 0 |
| .IP "\fB\-\-no\-fatal\-warnings\fR" 4 |
| .IX Item "--no-fatal-warnings" |
| .PD |
| Treat all warnings as errors. The default behaviour can be restored |
| with the option \fB\-\-no\-fatal\-warnings\fR. |
| .IP "\fB\-\-force\-exe\-suffix\fR" 4 |
| .IX Item "--force-exe-suffix" |
| Make sure that an output file has a .exe suffix. |
| .Sp |
| If a successfully built fully linked output file does not have a |
| \&\f(CW\*(C`.exe\*(C'\fR or \f(CW\*(C`.dll\*(C'\fR suffix, this option forces the linker to copy |
| the output file to one of the same name with a \f(CW\*(C`.exe\*(C'\fR suffix. This |
| option is useful when using unmodified Unix makefiles on a Microsoft |
| Windows host, since some versions of Windows won't run an image unless |
| it ends in a \f(CW\*(C`.exe\*(C'\fR suffix. |
| .IP "\fB\-\-gc\-sections\fR" 4 |
| .IX Item "--gc-sections" |
| .PD 0 |
| .IP "\fB\-\-no\-gc\-sections\fR" 4 |
| .IX Item "--no-gc-sections" |
| .PD |
| Enable garbage collection of unused input sections. It is ignored on |
| targets that do not support this option. The default behaviour (of not |
| performing this garbage collection) can be restored by specifying |
| \&\fB\-\-no\-gc\-sections\fR on the command line. |
| .Sp |
| \&\fB\-\-gc\-sections\fR decides which input sections are used by |
| examining symbols and relocations. The section containing the entry |
| symbol and all sections containing symbols undefined on the |
| command-line will be kept, as will sections containing symbols |
| referenced by dynamic objects. Note that when building shared |
| libraries, the linker must assume that any visible symbol is |
| referenced. Once this initial set of sections has been determined, |
| the linker recursively marks as used any section referenced by their |
| relocations. See \fB\-\-entry\fR and \fB\-\-undefined\fR. |
| .Sp |
| This option can be set when doing a partial link (enabled with option |
| \&\fB\-r\fR). In this case the root of symbols kept must be explicitly |
| specified either by an \fB\-\-entry\fR or \fB\-\-undefined\fR option or by |
| a \f(CW\*(C`ENTRY\*(C'\fR command in the linker script. |
| .IP "\fB\-\-print\-gc\-sections\fR" 4 |
| .IX Item "--print-gc-sections" |
| .PD 0 |
| .IP "\fB\-\-no\-print\-gc\-sections\fR" 4 |
| .IX Item "--no-print-gc-sections" |
| .PD |
| List all sections removed by garbage collection. The listing is |
| printed on stderr. This option is only effective if garbage |
| collection has been enabled via the \fB\-\-gc\-sections\fR) option. The |
| default behaviour (of not listing the sections that are removed) can |
| be restored by specifying \fB\-\-no\-print\-gc\-sections\fR on the command |
| line. |
| .IP "\fB\-\-print\-output\-format\fR" 4 |
| .IX Item "--print-output-format" |
| Print the name of the default output format (perhaps influenced by |
| other command-line options). This is the string that would appear |
| in an \f(CW\*(C`OUTPUT_FORMAT\*(C'\fR linker script command. |
| .IP "\fB\-\-help\fR" 4 |
| .IX Item "--help" |
| Print a summary of the command-line options on the standard output and exit. |
| .IP "\fB\-\-target\-help\fR" 4 |
| .IX Item "--target-help" |
| Print a summary of all target specific options on the standard output and exit. |
| .IP "\fB\-Map=\fR\fImapfile\fR" 4 |
| .IX Item "-Map=mapfile" |
| Print a link map to the file \fImapfile\fR. See the description of the |
| \&\fB\-M\fR option, above. |
| .IP "\fB\-\-no\-keep\-memory\fR" 4 |
| .IX Item "--no-keep-memory" |
| \&\fBld\fR normally optimizes for speed over memory usage by caching the |
| symbol tables of input files in memory. This option tells \fBld\fR to |
| instead optimize for memory usage, by rereading the symbol tables as |
| necessary. This may be required if \fBld\fR runs out of memory space |
| while linking a large executable. |
| .IP "\fB\-\-no\-undefined\fR" 4 |
| .IX Item "--no-undefined" |
| .PD 0 |
| .IP "\fB\-z defs\fR" 4 |
| .IX Item "-z defs" |
| .PD |
| Report unresolved symbol references from regular object files. This |
| is done even if the linker is creating a non-symbolic shared library. |
| The switch \fB\-\-[no\-]allow\-shlib\-undefined\fR controls the |
| behaviour for reporting unresolved references found in shared |
| libraries being linked in. |
| .IP "\fB\-\-allow\-multiple\-definition\fR" 4 |
| .IX Item "--allow-multiple-definition" |
| .PD 0 |
| .IP "\fB\-z muldefs\fR" 4 |
| .IX Item "-z muldefs" |
| .PD |
| Normally when a symbol is defined multiple times, the linker will |
| report a fatal error. These options allow multiple definitions and the |
| first definition will be used. |
| .IP "\fB\-\-allow\-shlib\-undefined\fR" 4 |
| .IX Item "--allow-shlib-undefined" |
| .PD 0 |
| .IP "\fB\-\-no\-allow\-shlib\-undefined\fR" 4 |
| .IX Item "--no-allow-shlib-undefined" |
| .PD |
| Allows or disallows undefined symbols in shared libraries. |
| This switch is similar to \fB\-\-no\-undefined\fR except that it |
| determines the behaviour when the undefined symbols are in a |
| shared library rather than a regular object file. It does not affect |
| how undefined symbols in regular object files are handled. |
| .Sp |
| The default behaviour is to report errors for any undefined symbols |
| referenced in shared libraries if the linker is being used to create |
| an executable, but to allow them if the linker is being used to create |
| a shared library. |
| .Sp |
| The reasons for allowing undefined symbol references in shared |
| libraries specified at link time are that: |
| .RS 4 |
| .IP "\(bu" 4 |
| A shared library specified at link time may not be the same as the one |
| that is available at load time, so the symbol might actually be |
| resolvable at load time. |
| .IP "\(bu" 4 |
| There are some operating systems, eg BeOS and \s-1HPPA\s0, where undefined |
| symbols in shared libraries are normal. |
| .Sp |
| The BeOS kernel for example patches shared libraries at load time to |
| select whichever function is most appropriate for the current |
| architecture. This is used, for example, to dynamically select an |
| appropriate memset function. |
| .RE |
| .RS 4 |
| .RE |
| .IP "\fB\-\-no\-undefined\-version\fR" 4 |
| .IX Item "--no-undefined-version" |
| Normally when a symbol has an undefined version, the linker will ignore |
| it. This option disallows symbols with undefined version and a fatal error |
| will be issued instead. |
| .IP "\fB\-\-default\-symver\fR" 4 |
| .IX Item "--default-symver" |
| Create and use a default symbol version (the soname) for unversioned |
| exported symbols. |
| .IP "\fB\-\-default\-imported\-symver\fR" 4 |
| .IX Item "--default-imported-symver" |
| Create and use a default symbol version (the soname) for unversioned |
| imported symbols. |
| .IP "\fB\-\-no\-warn\-mismatch\fR" 4 |
| .IX Item "--no-warn-mismatch" |
| Normally \fBld\fR 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 \fBld\fR 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. |
| .IP "\fB\-\-no\-warn\-search\-mismatch\fR" 4 |
| .IX Item "--no-warn-search-mismatch" |
| Normally \fBld\fR will give a warning if it finds an incompatible |
| library during a library search. This option silences the warning. |
| .IP "\fB\-\-no\-whole\-archive\fR" 4 |
| .IX Item "--no-whole-archive" |
| Turn off the effect of the \fB\-\-whole\-archive\fR option for subsequent |
| archive files. |
| .IP "\fB\-\-noinhibit\-exec\fR" 4 |
| .IX 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. |
| .IP "\fB\-nostdlib\fR" 4 |
| .IX Item "-nostdlib" |
| Only search library directories explicitly specified on the |
| command line. Library directories specified in linker scripts |
| (including linker scripts specified on the command line) are ignored. |
| .IP "\fB\-\-oformat=\fR\fIoutput-format\fR" 4 |
| .IX Item "--oformat=output-format" |
| \&\fBld\fR may be configured to support more than one kind of object |
| file. If your \fBld\fR is configured this way, you can use the |
| \&\fB\-\-oformat\fR option to specify the binary format for the output |
| object file. Even when \fBld\fR is configured to support alternative |
| object formats, you don't usually need to specify this, as \fBld\fR |
| should be configured to produce as a default output format the most |
| usual format on each machine. \fIoutput-format\fR is a text string, the |
| name of a particular format supported by the \s-1BFD\s0 libraries. (You can |
| list the available binary formats with \fBobjdump \-i\fR.) The script |
| command \f(CW\*(C`OUTPUT_FORMAT\*(C'\fR can also specify the output format, but |
| this option overrides it. |
| .IP "\fB\-pie\fR" 4 |
| .IX Item "-pie" |
| .PD 0 |
| .IP "\fB\-\-pic\-executable\fR" 4 |
| .IX Item "--pic-executable" |
| .PD |
| Create a position independent executable. This is currently only supported on |
| \&\s-1ELF\s0 platforms. Position independent executables are similar to shared |
| libraries in that they are relocated by the dynamic linker to the virtual |
| address the \s-1OS\s0 chooses for them (which can vary between invocations). Like |
| normal dynamically linked executables they can be executed and symbols |
| defined in the executable cannot be overridden by shared libraries. |
| .IP "\fB\-qmagic\fR" 4 |
| .IX Item "-qmagic" |
| This option is ignored for Linux compatibility. |
| .IP "\fB\-Qy\fR" 4 |
| .IX Item "-Qy" |
| This option is ignored for \s-1SVR4\s0 compatibility. |
| .IP "\fB\-\-relax\fR" 4 |
| .IX Item "--relax" |
| .PD 0 |
| .IP "\fB\-\-no\-relax\fR" 4 |
| .IX Item "--no-relax" |
| .PD |
| An option with machine dependent effects. |
| This option is only supported on a few targets. |
| .Sp |
| On some platforms the \fB\-\-relax\fR option performs target specific, |
| global optimizations that become possible when the linker resolves |
| addressing in the program, such as relaxing address modes, |
| synthesizing new instructions, selecting shorter version of current |
| instructions, and combining constant values. |
| .Sp |
| On some platforms these link time global optimizations may make symbolic |
| debugging of the resulting executable impossible. |
| This is known to be the case for the Matsushita \s-1MN10200\s0 and \s-1MN10300\s0 |
| family of processors. |
| .Sp |
| On platforms where this is not supported, \fB\-\-relax\fR is accepted, |
| but ignored. |
| .Sp |
| On platforms where \fB\-\-relax\fR is accepted the option |
| \&\fB\-\-no\-relax\fR can be used to disable the feature. |
| .IP "\fB\-\-retain\-symbols\-file=\fR\fIfilename\fR" 4 |
| .IX Item "--retain-symbols-file=filename" |
| Retain \fIonly\fR the symbols listed in the file \fIfilename\fR, |
| discarding all others. \fIfilename\fR is simply a flat file, with one |
| symbol name per line. This option is especially useful in environments |
| (such as VxWorks) |
| where a large global symbol table is accumulated gradually, to conserve |
| run-time memory. |
| .Sp |
| \&\fB\-\-retain\-symbols\-file\fR does \fInot\fR discard undefined symbols, |
| or symbols needed for relocations. |
| .Sp |
| You may only specify \fB\-\-retain\-symbols\-file\fR once in the command |
| line. It overrides \fB\-s\fR and \fB\-S\fR. |
| .IP "\fB\-rpath=\fR\fIdir\fR" 4 |
| .IX Item "-rpath=dir" |
| Add a directory to the runtime library search path. This is used when |
| linking an \s-1ELF\s0 executable with shared objects. All \fB\-rpath\fR |
| arguments are concatenated and passed to the runtime linker, which uses |
| them to locate shared objects at runtime. The \fB\-rpath\fR option is |
| also used when locating shared objects which are needed by shared |
| objects explicitly included in the link; see the description of the |
| \&\fB\-rpath\-link\fR option. If \fB\-rpath\fR is not used when linking an |
| \&\s-1ELF\s0 executable, the contents of the environment variable |
| \&\f(CW\*(C`LD_RUN_PATH\*(C'\fR will be used if it is defined. |
| .Sp |
| The \fB\-rpath\fR option may also be used on SunOS. By default, on |
| SunOS, the linker will form a runtime search patch out of all the |
| \&\fB\-L\fR options it is given. If a \fB\-rpath\fR option is used, the |
| runtime search path will be formed exclusively using the \fB\-rpath\fR |
| options, ignoring the \fB\-L\fR options. This can be useful when using |
| gcc, which adds many \fB\-L\fR options which may be on \s-1NFS\s0 mounted |
| file systems. |
| .Sp |
| For compatibility with other \s-1ELF\s0 linkers, if the \fB\-R\fR option is |
| followed by a directory name, rather than a file name, it is treated as |
| the \fB\-rpath\fR option. |
| .IP "\fB\-rpath\-link=\fR\fIdir\fR" 4 |
| .IX Item "-rpath-link=dir" |
| When using \s-1ELF\s0 or SunOS, one shared library may require another. This |
| happens when an \f(CW\*(C`ld \-shared\*(C'\fR link includes a shared library as one |
| of the input files. |
| .Sp |
| 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 \fB\-rpath\-link\fR option |
| specifies the first set of directories to search. The |
| \&\fB\-rpath\-link\fR option may specify a sequence of directory names |
| either by specifying a list of names separated by colons, or by |
| appearing multiple times. |
| .Sp |
| 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. |
| .Sp |
| The linker uses the following search paths to locate required shared |
| libraries: |
| .RS 4 |
| .IP "1." 4 |
| Any directories specified by \fB\-rpath\-link\fR options. |
| .IP "2." 4 |
| Any directories specified by \fB\-rpath\fR options. The difference |
| between \fB\-rpath\fR and \fB\-rpath\-link\fR is that directories |
| specified by \fB\-rpath\fR options are included in the executable and |
| used at runtime, whereas the \fB\-rpath\-link\fR option is only effective |
| at link time. Searching \fB\-rpath\fR in this way is only supported |
| by native linkers and cross linkers which have been configured with |
| the \fB\-\-with\-sysroot\fR option. |
| .IP "3." 4 |
| On an \s-1ELF\s0 system, for native linkers, if the \fB\-rpath\fR and |
| \&\fB\-rpath\-link\fR options were not used, search the contents of the |
| environment variable \f(CW\*(C`LD_RUN_PATH\*(C'\fR. |
| .IP "4." 4 |
| On SunOS, if the \fB\-rpath\fR option was not used, search any |
| directories specified using \fB\-L\fR options. |
| .IP "5." 4 |
| For a native linker, search the contents of the environment |
| variable \f(CW\*(C`LD_LIBRARY_PATH\*(C'\fR. |
| .IP "6." 4 |
| For a native \s-1ELF\s0 linker, the directories in \f(CW\*(C`DT_RUNPATH\*(C'\fR or |
| \&\f(CW\*(C`DT_RPATH\*(C'\fR of a shared library are searched for shared |
| libraries needed by it. The \f(CW\*(C`DT_RPATH\*(C'\fR entries are ignored if |
| \&\f(CW\*(C`DT_RUNPATH\*(C'\fR entries exist. |
| .IP "7." 4 |
| The default directories, normally \fI/lib\fR and \fI/usr/lib\fR. |
| .IP "8." 4 |
| For a native linker on an \s-1ELF\s0 system, if the file \fI/etc/ld.so.conf\fR |
| exists, the list of directories found in that file. |
| .RE |
| .RS 4 |
| .Sp |
| If the required shared library is not found, the linker will issue a |
| warning and continue with the link. |
| .RE |
| .IP "\fB\-shared\fR" 4 |
| .IX Item "-shared" |
| .PD 0 |
| .IP "\fB\-Bshareable\fR" 4 |
| .IX Item "-Bshareable" |
| .PD |
| Create a shared library. This is currently only supported on \s-1ELF\s0, \s-1XCOFF\s0 |
| and SunOS platforms. On SunOS, the linker will automatically create a |
| shared library if the \fB\-e\fR option is not used and there are |
| undefined symbols in the link. |
| .IP "\fB\-\-sort\-common\fR" 4 |
| .IX Item "--sort-common" |
| .PD 0 |
| .IP "\fB\-\-sort\-common=ascending\fR" 4 |
| .IX Item "--sort-common=ascending" |
| .IP "\fB\-\-sort\-common=descending\fR" 4 |
| .IX Item "--sort-common=descending" |
| .PD |
| This option tells \fBld\fR to sort the common symbols by alignment in |
| ascending or descending order when it places them in the appropriate output |
| sections. The symbol alignments considered are sixteen-byte or larger, |
| eight-byte, four-byte, two-byte, and one-byte. This is to prevent gaps |
| between symbols due to alignment constraints. If no sorting order is |
| specified, then descending order is assumed. |
| .IP "\fB\-\-sort\-section=name\fR" 4 |
| .IX Item "--sort-section=name" |
| This option will apply \f(CW\*(C`SORT_BY_NAME\*(C'\fR to all wildcard section |
| patterns in the linker script. |
| .IP "\fB\-\-sort\-section=alignment\fR" 4 |
| .IX Item "--sort-section=alignment" |
| This option will apply \f(CW\*(C`SORT_BY_ALIGNMENT\*(C'\fR to all wildcard section |
| patterns in the linker script. |
| .IP "\fB\-\-split\-by\-file[=\fR\fIsize\fR\fB]\fR" 4 |
| .IX Item "--split-by-file[=size]" |
| Similar to \fB\-\-split\-by\-reloc\fR but creates a new output section for |
| each input file when \fIsize\fR is reached. \fIsize\fR defaults to a |
| size of 1 if not given. |
| .IP "\fB\-\-split\-by\-reloc[=\fR\fIcount\fR\fB]\fR" 4 |
| .IX Item "--split-by-reloc[=count]" |
| Tries to creates extra sections in the output file so that no single |
| output section in the file contains more than \fIcount\fR relocations. |
| This is useful when generating huge relocatable files for downloading into |
| certain real time kernels with the \s-1COFF\s0 object file format; since \s-1COFF\s0 |
| 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 \fIcount\fR relocations one output section will contain that |
| many relocations. \fIcount\fR defaults to a value of 32768. |
| .IP "\fB\-\-stats\fR" 4 |
| .IX Item "--stats" |
| Compute and display statistics about the operation of the linker, such |
| as execution time and memory usage. |
| .IP "\fB\-\-sysroot=\fR\fIdirectory\fR" 4 |
| .IX Item "--sysroot=directory" |
| Use \fIdirectory\fR as the location of the sysroot, overriding the |
| configure-time default. This option is only supported by linkers |
| that were configured using \fB\-\-with\-sysroot\fR. |
| .IP "\fB\-\-traditional\-format\fR" 4 |
| .IX Item "--traditional-format" |
| For some targets, the output of \fBld\fR is different in some ways from |
| the output of some existing linker. This switch requests \fBld\fR to |
| use the traditional format instead. |
| .Sp |
| For example, on SunOS, \fBld\fR 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 |
| \&\f(CW\*(C`dbx\*(C'\fR program can not read the resulting program (\f(CW\*(C`gdb\*(C'\fR has no |
| trouble). The \fB\-\-traditional\-format\fR switch tells \fBld\fR to not |
| combine duplicate entries. |
| .IP "\fB\-\-section\-start=\fR\fIsectionname\fR\fB=\fR\fIorg\fR" 4 |
| .IX Item "--section-start=sectionname=org" |
| Locate a section in the output file at the absolute |
| address given by \fIorg\fR. You may use this option as many |
| times as necessary to locate multiple sections in the command |
| line. |
| \&\fIorg\fR must be a single hexadecimal integer; |
| for compatibility with other linkers, you may omit the leading |
| \&\fB0x\fR usually associated with hexadecimal values. \fINote:\fR there |
| should be no white space between \fIsectionname\fR, the equals |
| sign ("\fB=\fR"), and \fIorg\fR. |
| .IP "\fB\-Tbss=\fR\fIorg\fR" 4 |
| .IX Item "-Tbss=org" |
| .PD 0 |
| .IP "\fB\-Tdata=\fR\fIorg\fR" 4 |
| .IX Item "-Tdata=org" |
| .IP "\fB\-Ttext=\fR\fIorg\fR" 4 |
| .IX Item "-Ttext=org" |
| .PD |
| Same as \fB\-\-section\-start\fR, with \f(CW\*(C`.bss\*(C'\fR, \f(CW\*(C`.data\*(C'\fR or |
| \&\f(CW\*(C`.text\*(C'\fR as the \fIsectionname\fR. |
| .IP "\fB\-Ttext\-segment=\fR\fIorg\fR" 4 |
| .IX Item "-Ttext-segment=org" |
| When creating an \s-1ELF\s0 executable or shared object, it will set the address |
| of the first byte of the text segment. |
| .IP "\fB\-Trodata\-segment=\fR\fIorg\fR" 4 |
| .IX Item "-Trodata-segment=org" |
| When creating an \s-1ELF\s0 executable or shared object for a target where |
| the read-only data is in its own segment separate from the executable |
| text, it will set the address of the first byte of the read-only data segment. |
| .IP "\fB\-Tldata\-segment=\fR\fIorg\fR" 4 |
| .IX Item "-Tldata-segment=org" |
| When creating an \s-1ELF\s0 executable or shared object for x86\-64 medium memory |
| model, it will set the address of the first byte of the ldata segment. |
| .IP "\fB\-\-unresolved\-symbols=\fR\fImethod\fR" 4 |
| .IX Item "--unresolved-symbols=method" |
| Determine how to handle unresolved symbols. There are four possible |
| values for \fBmethod\fR: |
| .RS 4 |
| .IP "\fBignore-all\fR" 4 |
| .IX Item "ignore-all" |
| Do not report any unresolved symbols. |
| .IP "\fBreport-all\fR" 4 |
| .IX Item "report-all" |
| Report all unresolved symbols. This is the default. |
| .IP "\fBignore-in-object-files\fR" 4 |
| .IX Item "ignore-in-object-files" |
| Report unresolved symbols that are contained in shared libraries, but |
| ignore them if they come from regular object files. |
| .IP "\fBignore-in-shared-libs\fR" 4 |
| .IX Item "ignore-in-shared-libs" |
| Report unresolved symbols that come from regular object files, but |
| ignore them if they come from shared libraries. This can be useful |
| when creating a dynamic binary and it is known that all the shared |
| libraries that it should be referencing are included on the linker's |
| command line. |
| .RE |
| .RS 4 |
| .Sp |
| The behaviour for shared libraries on their own can also be controlled |
| by the \fB\-\-[no\-]allow\-shlib\-undefined\fR option. |
| .Sp |
| Normally the linker will generate an error message for each reported |
| unresolved symbol but the option \fB\-\-warn\-unresolved\-symbols\fR |
| can change this to a warning. |
| .RE |
| .IP "\fB\-\-dll\-verbose\fR" 4 |
| .IX Item "--dll-verbose" |
| .PD 0 |
| .IP "\fB\-\-verbose[=\fR\fI\s-1NUMBER\s0\fR\fB]\fR" 4 |
| .IX Item "--verbose[=NUMBER]" |
| .PD |
| Display the version number for \fBld\fR and list the linker emulations |
| supported. Display which input files can and cannot be opened. Display |
| the linker script being used by the linker. If the optional \fI\s-1NUMBER\s0\fR |
| argument > 1, plugin symbol status will also be displayed. |
| .IP "\fB\-\-version\-script=\fR\fIversion-scriptfile\fR" 4 |
| .IX Item "--version-script=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 hierarchy for the library being created. This option |
| is only fully supported on \s-1ELF\s0 platforms which support shared libraries; |
| see \fB\s-1VERSION\s0\fR. It is partially supported on \s-1PE\s0 platforms, which can |
| use version scripts to filter symbol visibility in auto-export mode: any |
| symbols marked \fBlocal\fR in the version script will not be exported. |
| .IP "\fB\-\-warn\-common\fR" 4 |
| .IX 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. |
| .Sp |
| There are three kinds of global symbols, illustrated here by C examples: |
| .RS 4 |
| .IP "\fBint i = 1;\fR" 4 |
| .IX Item "int i = 1;" |
| A definition, which goes in the initialized data section of the output |
| file. |
| .IP "\fBextern int i;\fR" 4 |
| .IX 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. |
| .IP "\fBint i;\fR" 4 |
| .IX 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. |
| .RE |
| .RS 4 |
| .Sp |
| The \fB\-\-warn\-common\fR 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. |
| .IP "1." 4 |
| Turning a common symbol into a reference, because there is already a |
| definition for the symbol. |
| .Sp |
| .Vb 3 |
| \& <file>(<section>): warning: common of \`<symbol>\*(Aq |
| \& overridden by definition |
| \& <file>(<section>): warning: defined here |
| .Ve |
| .IP "2." 4 |
| 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. |
| .Sp |
| .Vb 3 |
| \& <file>(<section>): warning: definition of \`<symbol>\*(Aq |
| \& overriding common |
| \& <file>(<section>): warning: common is here |
| .Ve |
| .IP "3." 4 |
| Merging a common symbol with a previous same-sized common symbol. |
| .Sp |
| .Vb 3 |
| \& <file>(<section>): warning: multiple common |
| \& of \`<symbol>\*(Aq |
| \& <file>(<section>): warning: previous common is here |
| .Ve |
| .IP "4." 4 |
| Merging a common symbol with a previous larger common symbol. |
| .Sp |
| .Vb 3 |
| \& <file>(<section>): warning: common of \`<symbol>\*(Aq |
| \& overridden by larger common |
| \& <file>(<section>): warning: larger common is here |
| .Ve |
| .IP "5." 4 |
| Merging a common symbol with a previous smaller common symbol. This is |
| the same as the previous case, except that the symbols are |
| encountered in a different order. |
| .Sp |
| .Vb 3 |
| \& <file>(<section>): warning: common of \`<symbol>\*(Aq |
| \& overriding smaller common |
| \& <file>(<section>): warning: smaller common is here |
| .Ve |
| .RE |
| .RS 4 |
| .RE |
| .IP "\fB\-\-warn\-constructors\fR" 4 |
| .IX Item "--warn-constructors" |
| Warn if any global constructors are used. This is only useful for a few |
| object file formats. For formats like \s-1COFF\s0 or \s-1ELF\s0, the linker can not |
| detect the use of global constructors. |
| .IP "\fB\-\-warn\-multiple\-gp\fR" 4 |
| .IX Item "--warn-multiple-gp" |
| Warn if multiple global pointer values are required in the output file. |
| This is only meaningful for certain processors, such as the Alpha. |
| Specifically, some processors put large-valued constants in a special |
| section. A special register (the global pointer) points into the middle |
| of this section, so that constants can be loaded efficiently via a |
| base-register relative addressing mode. Since the offset in |
| base-register relative mode is fixed and relatively small (e.g., 16 |
| bits), this limits the maximum size of the constant pool. Thus, in |
| large programs, it is often necessary to use multiple global pointer |
| values in order to be able to address all possible constants. This |
| option causes a warning to be issued whenever this case occurs. |
| .IP "\fB\-\-warn\-once\fR" 4 |
| .IX Item "--warn-once" |
| Only warn once for each undefined symbol, rather than once per module |
| which refers to it. |
| .IP "\fB\-\-warn\-section\-align\fR" 4 |
| .IX Item "--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 \f(CW\*(C`SECTIONS\*(C'\fR command does not specify a start address for |
| the section. |
| .IP "\fB\-\-warn\-shared\-textrel\fR" 4 |
| .IX Item "--warn-shared-textrel" |
| Warn if the linker adds a \s-1DT_TEXTREL\s0 to a shared object. |
| .IP "\fB\-\-warn\-alternate\-em\fR" 4 |
| .IX Item "--warn-alternate-em" |
| Warn if an object has alternate \s-1ELF\s0 machine code. |
| .IP "\fB\-\-warn\-unresolved\-symbols\fR" 4 |
| .IX Item "--warn-unresolved-symbols" |
| If the linker is going to report an unresolved symbol (see the option |
| \&\fB\-\-unresolved\-symbols\fR) it will normally generate an error. |
| This option makes it generate a warning instead. |
| .IP "\fB\-\-error\-unresolved\-symbols\fR" 4 |
| .IX Item "--error-unresolved-symbols" |
| This restores the linker's default behaviour of generating errors when |
| it is reporting unresolved symbols. |
| .IP "\fB\-\-whole\-archive\fR" 4 |
| .IX Item "--whole-archive" |
| For each archive mentioned on the command line after the |
| \&\fB\-\-whole\-archive\fR 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. This option may be used more than once. |
| .Sp |
| Two notes when using this option from gcc: First, gcc doesn't know |
| about this option, so you have to use \fB\-Wl,\-whole\-archive\fR. |
| Second, don't forget to use \fB\-Wl,\-no\-whole\-archive\fR after your |
| list of archives, because gcc will add its own list of archives to |
| your link and you may not want this flag to affect those as well. |
| .IP "\fB\-\-wrap=\fR\fIsymbol\fR" 4 |
| .IX Item "--wrap=symbol" |
| Use a wrapper function for \fIsymbol\fR. Any undefined reference to |
| \&\fIsymbol\fR will be resolved to \f(CW\*(C`_\|_wrap_\f(CIsymbol\f(CW\*(C'\fR. Any |
| undefined reference to \f(CW\*(C`_\|_real_\f(CIsymbol\f(CW\*(C'\fR will be resolved to |
| \&\fIsymbol\fR. |
| .Sp |
| This can be used to provide a wrapper for a system function. The |
| wrapper function should be called \f(CW\*(C`_\|_wrap_\f(CIsymbol\f(CW\*(C'\fR. If it |
| wishes to call the system function, it should call |
| \&\f(CW\*(C`_\|_real_\f(CIsymbol\f(CW\*(C'\fR. |
| .Sp |
| Here is a trivial example: |
| .Sp |
| .Vb 6 |
| \& void * |
| \& _\|_wrap_malloc (size_t c) |
| \& { |
| \& printf ("malloc called with %zu\en", c); |
| \& return _\|_real_malloc (c); |
| \& } |
| .Ve |
| .Sp |
| If you link other code with this file using \fB\-\-wrap malloc\fR, then |
| all calls to \f(CW\*(C`malloc\*(C'\fR will call the function \f(CW\*(C`_\|_wrap_malloc\*(C'\fR |
| instead. The call to \f(CW\*(C`_\|_real_malloc\*(C'\fR in \f(CW\*(C`_\|_wrap_malloc\*(C'\fR will |
| call the real \f(CW\*(C`malloc\*(C'\fR function. |
| .Sp |
| You may wish to provide a \f(CW\*(C`_\|_real_malloc\*(C'\fR function as well, so that |
| links without the \fB\-\-wrap\fR option will succeed. If you do this, |
| you should not put the definition of \f(CW\*(C`_\|_real_malloc\*(C'\fR in the same |
| file as \f(CW\*(C`_\|_wrap_malloc\*(C'\fR; if you do, the assembler may resolve the |
| call before the linker has a chance to wrap it to \f(CW\*(C`malloc\*(C'\fR. |
| .IP "\fB\-\-eh\-frame\-hdr\fR" 4 |
| .IX Item "--eh-frame-hdr" |
| Request creation of \f(CW\*(C`.eh_frame_hdr\*(C'\fR section and \s-1ELF\s0 |
| \&\f(CW\*(C`PT_GNU_EH_FRAME\*(C'\fR segment header. |
| .IP "\fB\-\-no\-ld\-generated\-unwind\-info\fR" 4 |
| .IX Item "--no-ld-generated-unwind-info" |
| Request creation of \f(CW\*(C`.eh_frame\*(C'\fR unwind info for linker |
| generated code sections like \s-1PLT\s0. This option is on by default |
| if linker generated unwind info is supported. |
| .IP "\fB\-\-enable\-new\-dtags\fR" 4 |
| .IX Item "--enable-new-dtags" |
| .PD 0 |
| .IP "\fB\-\-disable\-new\-dtags\fR" 4 |
| .IX Item "--disable-new-dtags" |
| .PD |
| This linker can create the new dynamic tags in \s-1ELF\s0. But the older \s-1ELF\s0 |
| systems may not understand them. If you specify |
| \&\fB\-\-enable\-new\-dtags\fR, the new dynamic tags will be created as needed |
| and older dynamic tags will be omitted. |
| If you specify \fB\-\-disable\-new\-dtags\fR, no new dynamic tags will be |
| created. By default, the new dynamic tags are not created. Note that |
| those options are only available for \s-1ELF\s0 systems. |
| .IP "\fB\-\-hash\-size=\fR\fInumber\fR" 4 |
| .IX Item "--hash-size=number" |
| Set the default size of the linker's hash tables to a prime number |
| close to \fInumber\fR. Increasing this value can reduce the length of |
| time it takes the linker to perform its tasks, at the expense of |
| increasing the linker's memory requirements. Similarly reducing this |
| value can reduce the memory requirements at the expense of speed. |
| .IP "\fB\-\-hash\-style=\fR\fIstyle\fR" 4 |
| .IX Item "--hash-style=style" |
| Set the type of linker's hash table(s). \fIstyle\fR can be either |
| \&\f(CW\*(C`sysv\*(C'\fR for classic \s-1ELF\s0 \f(CW\*(C`.hash\*(C'\fR section, \f(CW\*(C`gnu\*(C'\fR for |
| new style \s-1GNU\s0 \f(CW\*(C`.gnu.hash\*(C'\fR section or \f(CW\*(C`both\*(C'\fR for both |
| the classic \s-1ELF\s0 \f(CW\*(C`.hash\*(C'\fR and new style \s-1GNU\s0 \f(CW\*(C`.gnu.hash\*(C'\fR |
| hash tables. The default is \f(CW\*(C`sysv\*(C'\fR. |
| .IP "\fB\-\-reduce\-memory\-overheads\fR" 4 |
| .IX Item "--reduce-memory-overheads" |
| This option reduces memory requirements at ld runtime, at the expense of |
| linking speed. This was introduced to select the old O(n^2) algorithm |
| for link map file generation, rather than the new O(n) algorithm which uses |
| about 40% more memory for symbol storage. |
| .Sp |
| Another effect of the switch is to set the default hash table size to |
| 1021, which again saves memory at the cost of lengthening the linker's |
| run time. This is not done however if the \fB\-\-hash\-size\fR switch |
| has been used. |
| .Sp |
| The \fB\-\-reduce\-memory\-overheads\fR switch may be also be used to |
| enable other tradeoffs in future versions of the linker. |
| .IP "\fB\-\-build\-id\fR" 4 |
| .IX Item "--build-id" |
| .PD 0 |
| .IP "\fB\-\-build\-id=\fR\fIstyle\fR" 4 |
| .IX Item "--build-id=style" |
| .PD |
| Request creation of \f(CW\*(C`.note.gnu.build\-id\*(C'\fR \s-1ELF\s0 note section. |
| The contents of the note are unique bits identifying this linked |
| file. \fIstyle\fR can be \f(CW\*(C`uuid\*(C'\fR to use 128 random bits, |
| \&\f(CW\*(C`sha1\*(C'\fR to use a 160\-bit \s-1SHA1\s0 hash on the normative |
| parts of the output contents, \f(CW\*(C`md5\*(C'\fR to use a 128\-bit |
| \&\s-1MD5\s0 hash on the normative parts of the output contents, or |
| \&\f(CW\*(C`0x\f(CIhexstring\f(CW\*(C'\fR to use a chosen bit string specified as |
| an even number of hexadecimal digits (\f(CW\*(C`\-\*(C'\fR and \f(CW\*(C`:\*(C'\fR |
| characters between digit pairs are ignored). If \fIstyle\fR is |
| omitted, \f(CW\*(C`sha1\*(C'\fR is used. |
| .Sp |
| The \f(CW\*(C`md5\*(C'\fR and \f(CW\*(C`sha1\*(C'\fR styles produces an identifier |
| that is always the same in an identical output file, but will be |
| unique among all nonidentical output files. It is not intended |
| to be compared as a checksum for the file's contents. A linked |
| file may be changed later by other tools, but the build \s-1ID\s0 bit |
| string identifying the original linked file does not change. |
| .Sp |
| Passing \f(CW\*(C`none\*(C'\fR for \fIstyle\fR disables the setting from any |
| \&\f(CW\*(C`\-\-build\-id\*(C'\fR options earlier on the command line. |
| .PP |
| The i386 \s-1PE\s0 linker supports the \fB\-shared\fR option, which causes |
| the output to be a dynamically linked library (\s-1DLL\s0) instead of a |
| normal executable. You should name the output \f(CW\*(C`*.dll\*(C'\fR when you |
| use this option. In addition, the linker fully supports the standard |
| \&\f(CW\*(C`*.def\*(C'\fR files, which may be specified on the linker command line |
| like an object file (in fact, it should precede archives it exports |
| symbols from, to ensure that they get linked in, just like a normal |
| object file). |
| .PP |
| In addition to the options common to all targets, the i386 \s-1PE\s0 linker |
| support additional command line options that are specific to the i386 |
| \&\s-1PE\s0 target. Options that take values may be separated from their |
| values by either a space or an equals sign. |
| .IP "\fB\-\-add\-stdcall\-alias\fR" 4 |
| .IX Item "--add-stdcall-alias" |
| If given, symbols with a stdcall suffix (@\fInn\fR) will be exported |
| as-is and also with the suffix stripped. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-base\-file\fR \fIfile\fR" 4 |
| .IX Item "--base-file file" |
| Use \fIfile\fR as the name of a file in which to save the base |
| addresses of all the relocations needed for generating DLLs with |
| \&\fIdlltool\fR. |
| [This is an i386 \s-1PE\s0 specific option] |
| .IP "\fB\-\-dll\fR" 4 |
| .IX Item "--dll" |
| Create a \s-1DLL\s0 instead of a regular executable. You may also use |
| \&\fB\-shared\fR or specify a \f(CW\*(C`LIBRARY\*(C'\fR in a given \f(CW\*(C`.def\*(C'\fR |
| file. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-enable\-long\-section\-names\fR" 4 |
| .IX Item "--enable-long-section-names" |
| .PD 0 |
| .IP "\fB\-\-disable\-long\-section\-names\fR" 4 |
| .IX Item "--disable-long-section-names" |
| .PD |
| The \s-1PE\s0 variants of the Coff object format add an extension that permits |
| the use of section names longer than eight characters, the normal limit |
| for Coff. By default, these names are only allowed in object files, as |
| fully-linked executable images do not carry the Coff string table required |
| to support the longer names. As a \s-1GNU\s0 extension, it is possible to |
| allow their use in executable images as well, or to (probably pointlessly!) |
| disallow it in object files, by using these two options. Executable images |
| generated with these long section names are slightly non-standard, carrying |
| as they do a string table, and may generate confusing output when examined |
| with non-GNU PE-aware tools, such as file viewers and dumpers. However, |
| \&\s-1GDB\s0 relies on the use of \s-1PE\s0 long section names to find Dwarf\-2 debug |
| information sections in an executable image at runtime, and so if neither |
| option is specified on the command-line, \fBld\fR will enable long |
| section names, overriding the default and technically correct behaviour, |
| when it finds the presence of debug information while linking an executable |
| image and not stripping symbols. |
| [This option is valid for all \s-1PE\s0 targeted ports of the linker] |
| .IP "\fB\-\-enable\-stdcall\-fixup\fR" 4 |
| .IX Item "--enable-stdcall-fixup" |
| .PD 0 |
| .IP "\fB\-\-disable\-stdcall\-fixup\fR" 4 |
| .IX Item "--disable-stdcall-fixup" |
| .PD |
| If the link finds a symbol that it cannot resolve, it will attempt to |
| do \*(L"fuzzy linking\*(R" by looking for another defined symbol that differs |
| only in the format of the symbol name (cdecl vs stdcall) and will |
| resolve that symbol by linking to the match. For example, the |
| undefined symbol \f(CW\*(C`_foo\*(C'\fR might be linked to the function |
| \&\f(CW\*(C`_foo@12\*(C'\fR, or the undefined symbol \f(CW\*(C`_bar@16\*(C'\fR might be linked |
| to the function \f(CW\*(C`_bar\*(C'\fR. When the linker does this, it prints a |
| warning, since it normally should have failed to link, but sometimes |
| import libraries generated from third-party dlls may need this feature |
| to be usable. If you specify \fB\-\-enable\-stdcall\-fixup\fR, this |
| feature is fully enabled and warnings are not printed. If you specify |
| \&\fB\-\-disable\-stdcall\-fixup\fR, this feature is disabled and such |
| mismatches are considered to be errors. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-leading\-underscore\fR" 4 |
| .IX Item "--leading-underscore" |
| .PD 0 |
| .IP "\fB\-\-no\-leading\-underscore\fR" 4 |
| .IX Item "--no-leading-underscore" |
| .PD |
| For most targets default symbol-prefix is an underscore and is defined |
| in target's description. By this option it is possible to |
| disable/enable the default underscore symbol-prefix. |
| .IP "\fB\-\-export\-all\-symbols\fR" 4 |
| .IX Item "--export-all-symbols" |
| If given, all global symbols in the objects used to build a \s-1DLL\s0 will |
| be exported by the \s-1DLL\s0. Note that this is the default if there |
| otherwise wouldn't be any exported symbols. When symbols are |
| explicitly exported via \s-1DEF\s0 files or implicitly exported via function |
| attributes, the default is to not export anything else unless this |
| option is given. Note that the symbols \f(CW\*(C`DllMain@12\*(C'\fR, |
| \&\f(CW\*(C`DllEntryPoint@0\*(C'\fR, \f(CW\*(C`DllMainCRTStartup@12\*(C'\fR, and |
| \&\f(CW\*(C`impure_ptr\*(C'\fR will not be automatically |
| exported. Also, symbols imported from other DLLs will not be |
| re-exported, nor will symbols specifying the \s-1DLL\s0's internal layout |
| such as those beginning with \f(CW\*(C`_head_\*(C'\fR or ending with |
| \&\f(CW\*(C`_iname\*(C'\fR. In addition, no symbols from \f(CW\*(C`libgcc\*(C'\fR, |
| \&\f(CW\*(C`libstd++\*(C'\fR, \f(CW\*(C`libmingw32\*(C'\fR, or \f(CW\*(C`crtX.o\*(C'\fR will be exported. |
| Symbols whose names begin with \f(CW\*(C`_\|_rtti_\*(C'\fR or \f(CW\*(C`_\|_builtin_\*(C'\fR will |
| not be exported, to help with \*(C+ DLLs. Finally, there is an |
| extensive list of cygwin-private symbols that are not exported |
| (obviously, this applies on when building DLLs for cygwin targets). |
| These cygwin-excludes are: \f(CW\*(C`_cygwin_dll_entry@12\*(C'\fR, |
| \&\f(CW\*(C`_cygwin_crt0_common@8\*(C'\fR, \f(CW\*(C`_cygwin_noncygwin_dll_entry@12\*(C'\fR, |
| \&\f(CW\*(C`_fmode\*(C'\fR, \f(CW\*(C`_impure_ptr\*(C'\fR, \f(CW\*(C`cygwin_attach_dll\*(C'\fR, |
| \&\f(CW\*(C`cygwin_premain0\*(C'\fR, \f(CW\*(C`cygwin_premain1\*(C'\fR, \f(CW\*(C`cygwin_premain2\*(C'\fR, |
| \&\f(CW\*(C`cygwin_premain3\*(C'\fR, and \f(CW\*(C`environ\*(C'\fR. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-exclude\-symbols\fR \fIsymbol\fR\fB,\fR\fIsymbol\fR\fB,...\fR" 4 |
| .IX Item "--exclude-symbols symbol,symbol,..." |
| Specifies a list of symbols which should not be automatically |
| exported. The symbol names may be delimited by commas or colons. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-exclude\-all\-symbols\fR" 4 |
| .IX Item "--exclude-all-symbols" |
| Specifies no symbols should be automatically exported. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-file\-alignment\fR" 4 |
| .IX Item "--file-alignment" |
| 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 the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-heap\fR \fIreserve\fR" 4 |
| .IX Item "--heap reserve" |
| .PD 0 |
| .IP "\fB\-\-heap\fR \fIreserve\fR\fB,\fR\fIcommit\fR" 4 |
| .IX Item "--heap reserve,commit" |
| .PD |
| Specify the number of bytes of memory to reserve (and optionally commit) |
| to be used as heap for this program. The default is 1Mb reserved, 4K |
| committed. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-image\-base\fR \fIvalue\fR" 4 |
| .IX Item "--image-base value" |
| Use \fIvalue\fR 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 the need to relocate and improve performance of |
| your dlls, each should have a unique base address and not overlap any |
| other dlls. The default is 0x400000 for executables, and 0x10000000 |
| for dlls. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-kill\-at\fR" 4 |
| .IX Item "--kill-at" |
| If given, the stdcall suffixes (@\fInn\fR) will be stripped from |
| symbols before they are exported. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-large\-address\-aware\fR" 4 |
| .IX Item "--large-address-aware" |
| If given, the appropriate bit in the \*(L"Characteristics\*(R" field of the \s-1COFF\s0 |
| header is set to indicate that this executable supports virtual addresses |
| greater than 2 gigabytes. This should be used in conjunction with the /3GB |
| or /USERVA=\fIvalue\fR megabytes switch in the \*(L"[operating systems]\*(R" |
| section of the \s-1BOOT\s0.INI. Otherwise, this bit has no effect. |
| [This option is specific to \s-1PE\s0 targeted ports of the linker] |
| .IP "\fB\-\-major\-image\-version\fR \fIvalue\fR" 4 |
| .IX Item "--major-image-version value" |
| Sets the major number of the \*(L"image version\*(R". Defaults to 1. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-major\-os\-version\fR \fIvalue\fR" 4 |
| .IX Item "--major-os-version value" |
| Sets the major number of the \*(L"os version\*(R". Defaults to 4. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-major\-subsystem\-version\fR \fIvalue\fR" 4 |
| .IX Item "--major-subsystem-version value" |
| Sets the major number of the \*(L"subsystem version\*(R". Defaults to 4. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-minor\-image\-version\fR \fIvalue\fR" 4 |
| .IX Item "--minor-image-version value" |
| Sets the minor number of the \*(L"image version\*(R". Defaults to 0. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-minor\-os\-version\fR \fIvalue\fR" 4 |
| .IX Item "--minor-os-version value" |
| Sets the minor number of the \*(L"os version\*(R". Defaults to 0. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-minor\-subsystem\-version\fR \fIvalue\fR" 4 |
| .IX Item "--minor-subsystem-version value" |
| Sets the minor number of the \*(L"subsystem version\*(R". Defaults to 0. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-output\-def\fR \fIfile\fR" 4 |
| .IX Item "--output-def file" |
| The linker will create the file \fIfile\fR which will contain a \s-1DEF\s0 |
| file corresponding to the \s-1DLL\s0 the linker is generating. This \s-1DEF\s0 file |
| (which should be called \f(CW\*(C`*.def\*(C'\fR) may be used to create an import |
| library with \f(CW\*(C`dlltool\*(C'\fR or may be used as a reference to |
| automatically or implicitly exported symbols. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-out\-implib\fR \fIfile\fR" 4 |
| .IX Item "--out-implib file" |
| The linker will create the file \fIfile\fR which will contain an |
| import lib corresponding to the \s-1DLL\s0 the linker is generating. This |
| import lib (which should be called \f(CW\*(C`*.dll.a\*(C'\fR or \f(CW\*(C`*.a\*(C'\fR |
| may be used to link clients against the generated \s-1DLL\s0; this behaviour |
| makes it possible to skip a separate \f(CW\*(C`dlltool\*(C'\fR import library |
| creation step. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-enable\-auto\-image\-base\fR" 4 |
| .IX Item "--enable-auto-image-base" |
| Automatically choose the image base for DLLs, unless one is specified |
| using the \f(CW\*(C`\-\-image\-base\*(C'\fR argument. By using a hash generated |
| from the dllname to create unique image bases for each \s-1DLL\s0, in-memory |
| collisions and relocations which can delay program execution are |
| avoided. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-disable\-auto\-image\-base\fR" 4 |
| .IX Item "--disable-auto-image-base" |
| Do not automatically generate a unique image base. If there is no |
| user-specified image base (\f(CW\*(C`\-\-image\-base\*(C'\fR) then use the platform |
| default. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-dll\-search\-prefix\fR \fIstring\fR" 4 |
| .IX Item "--dll-search-prefix string" |
| When linking dynamically to a dll without an import library, |
| search for \f(CW\*(C`<string><basename>.dll\*(C'\fR in preference to |
| \&\f(CW\*(C`lib<basename>.dll\*(C'\fR. This behaviour allows easy distinction |
| between DLLs built for the various \*(L"subplatforms\*(R": native, cygwin, |
| uwin, pw, etc. For instance, cygwin DLLs typically use |
| \&\f(CW\*(C`\-\-dll\-search\-prefix=cyg\*(C'\fR. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-enable\-auto\-import\fR" 4 |
| .IX Item "--enable-auto-import" |
| Do sophisticated linking of \f(CW\*(C`_symbol\*(C'\fR to \f(CW\*(C`_\|_imp_\|_symbol\*(C'\fR for |
| \&\s-1DATA\s0 imports from DLLs, and create the necessary thunking symbols when |
| building the import libraries with those \s-1DATA\s0 exports. Note: Use of the |
| \&'auto\-import' extension will cause the text section of the image file |
| to be made writable. This does not conform to the PE-COFF format |
| specification published by Microsoft. |
| .Sp |
| Note \- use of the 'auto\-import' extension will also cause read only |
| data which would normally be placed into the .rdata section to be |
| placed into the .data section instead. This is in order to work |
| around a problem with consts that is described here: |
| http://www.cygwin.com/ml/cygwin/2004\-09/msg01101.html |
| .Sp |
| Using 'auto\-import' generally will 'just work' \*(-- but sometimes you may |
| see this message: |
| .Sp |
| "variable '<var>' can't be auto-imported. Please read the |
| documentation for ld's \f(CW\*(C`\-\-enable\-auto\-import\*(C'\fR for details." |
| .Sp |
| This message occurs when some (sub)expression accesses an address |
| ultimately given by the sum of two constants (Win32 import tables only |
| allow one). Instances where this may occur include accesses to member |
| fields of struct variables imported from a \s-1DLL\s0, as well as using a |
| constant index into an array variable imported from a \s-1DLL\s0. Any |
| multiword variable (arrays, structs, long long, etc) may trigger |
| this error condition. However, regardless of the exact data type |
| of the offending exported variable, ld will always detect it, issue |
| the warning, and exit. |
| .Sp |
| There are several ways to address this difficulty, regardless of the |
| data type of the exported variable: |
| .Sp |
| One way is to use \-\-enable\-runtime\-pseudo\-reloc switch. This leaves the task |
| of adjusting references in your client code for runtime environment, so |
| this method works only when runtime environment supports this feature. |
| .Sp |
| A second solution is to force one of the 'constants' to be a variable \*(-- |
| that is, unknown and un-optimizable at compile time. For arrays, |
| there are two possibilities: a) make the indexee (the array's address) |
| a variable, or b) make the 'constant' index a variable. Thus: |
| .Sp |
| .Vb 3 |
| \& extern type extern_array[]; |
| \& extern_array[1] \-\-> |
| \& { volatile type *t=extern_array; t[1] } |
| .Ve |
| .Sp |
| or |
| .Sp |
| .Vb 3 |
| \& extern type extern_array[]; |
| \& extern_array[1] \-\-> |
| \& { volatile int t=1; extern_array[t] } |
| .Ve |
| .Sp |
| For structs (and most other multiword data types) the only option |
| is to make the struct itself (or the long long, or the ...) variable: |
| .Sp |
| .Vb 3 |
| \& extern struct s extern_struct; |
| \& extern_struct.field \-\-> |
| \& { volatile struct s *t=&extern_struct; t\->field } |
| .Ve |
| .Sp |
| or |
| .Sp |
| .Vb 3 |
| \& extern long long extern_ll; |
| \& extern_ll \-\-> |
| \& { volatile long long * local_ll=&extern_ll; *local_ll } |
| .Ve |
| .Sp |
| A third method of dealing with this difficulty is to abandon |
| \&'auto\-import' for the offending symbol and mark it with |
| \&\f(CW\*(C`_\|_declspec(dllimport)\*(C'\fR. However, in practice that |
| requires using compile-time #defines to indicate whether you are |
| building a \s-1DLL\s0, building client code that will link to the \s-1DLL\s0, or |
| merely building/linking to a static library. In making the choice |
| between the various methods of resolving the 'direct address with |
| constant offset' problem, you should consider typical real-world usage: |
| .Sp |
| Original: |
| .Sp |
| .Vb 7 |
| \& \-\-foo.h |
| \& extern int arr[]; |
| \& \-\-foo.c |
| \& #include "foo.h" |
| \& void main(int argc, char **argv){ |
| \& printf("%d\en",arr[1]); |
| \& } |
| .Ve |
| .Sp |
| Solution 1: |
| .Sp |
| .Vb 9 |
| \& \-\-foo.h |
| \& extern int arr[]; |
| \& \-\-foo.c |
| \& #include "foo.h" |
| \& void main(int argc, char **argv){ |
| \& /* This workaround is for win32 and cygwin; do not "optimize" */ |
| \& volatile int *parr = arr; |
| \& printf("%d\en",parr[1]); |
| \& } |
| .Ve |
| .Sp |
| Solution 2: |
| .Sp |
| .Vb 10 |
| \& \-\-foo.h |
| \& /* Note: auto\-export is assumed (no _\|_declspec(dllexport)) */ |
| \& #if (defined(_WIN32) || defined(_\|_CYGWIN_\|_)) && \e |
| \& !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC)) |
| \& #define FOO_IMPORT _\|_declspec(dllimport) |
| \& #else |
| \& #define FOO_IMPORT |
| \& #endif |
| \& extern FOO_IMPORT int arr[]; |
| \& \-\-foo.c |
| \& #include "foo.h" |
| \& void main(int argc, char **argv){ |
| \& printf("%d\en",arr[1]); |
| \& } |
| .Ve |
| .Sp |
| A fourth way to avoid this problem is to re-code your |
| library to use a functional interface rather than a data interface |
| for the offending variables (e.g. \fIset_foo()\fR and \fIget_foo()\fR accessor |
| functions). |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-disable\-auto\-import\fR" 4 |
| .IX Item "--disable-auto-import" |
| Do not attempt to do sophisticated linking of \f(CW\*(C`_symbol\*(C'\fR to |
| \&\f(CW\*(C`_\|_imp_\|_symbol\*(C'\fR for \s-1DATA\s0 imports from DLLs. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-enable\-runtime\-pseudo\-reloc\fR" 4 |
| .IX Item "--enable-runtime-pseudo-reloc" |
| If your code contains expressions described in \-\-enable\-auto\-import section, |
| that is, \s-1DATA\s0 imports from \s-1DLL\s0 with non-zero offset, this switch will create |
| a vector of 'runtime pseudo relocations' which can be used by runtime |
| environment to adjust references to such data in your client code. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-disable\-runtime\-pseudo\-reloc\fR" 4 |
| .IX Item "--disable-runtime-pseudo-reloc" |
| Do not create pseudo relocations for non-zero offset \s-1DATA\s0 imports from |
| DLLs. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-enable\-extra\-pe\-debug\fR" 4 |
| .IX Item "--enable-extra-pe-debug" |
| Show additional debug info related to auto-import symbol thunking. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-section\-alignment\fR" 4 |
| .IX Item "--section-alignment" |
| Sets the section alignment. Sections in memory will always begin at |
| addresses which are a multiple of this number. Defaults to 0x1000. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-stack\fR \fIreserve\fR" 4 |
| .IX Item "--stack reserve" |
| .PD 0 |
| .IP "\fB\-\-stack\fR \fIreserve\fR\fB,\fR\fIcommit\fR" 4 |
| .IX Item "--stack reserve,commit" |
| .PD |
| Specify the number of bytes of memory to reserve (and optionally commit) |
| to be used as stack for this program. The default is 2Mb reserved, 4K |
| committed. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .IP "\fB\-\-subsystem\fR \fIwhich\fR" 4 |
| .IX Item "--subsystem which" |
| .PD 0 |
| .IP "\fB\-\-subsystem\fR \fIwhich\fR\fB:\fR\fImajor\fR" 4 |
| .IX Item "--subsystem which:major" |
| .IP "\fB\-\-subsystem\fR \fIwhich\fR\fB:\fR\fImajor\fR\fB.\fR\fIminor\fR" 4 |
| .IX Item "--subsystem which:major.minor" |
| .PD |
| Specifies the subsystem under which your program will execute. The |
| legal values for \fIwhich\fR are \f(CW\*(C`native\*(C'\fR, \f(CW\*(C`windows\*(C'\fR, |
| \&\f(CW\*(C`console\*(C'\fR, \f(CW\*(C`posix\*(C'\fR, and \f(CW\*(C`xbox\*(C'\fR. You may optionally set |
| the subsystem version also. Numeric values are also accepted for |
| \&\fIwhich\fR. |
| [This option is specific to the i386 \s-1PE\s0 targeted port of the linker] |
| .Sp |
| The following options set flags in the \f(CW\*(C`DllCharacteristics\*(C'\fR field |
| of the \s-1PE\s0 file header: |
| [These options are specific to \s-1PE\s0 targeted ports of the linker] |
| .IP "\fB\-\-dynamicbase\fR" 4 |
| .IX Item "--dynamicbase" |
| The image base address may be relocated using address space layout |
| randomization (\s-1ASLR\s0). This feature was introduced with \s-1MS\s0 Windows |
| Vista for i386 \s-1PE\s0 targets. |
| .IP "\fB\-\-forceinteg\fR" 4 |
| .IX Item "--forceinteg" |
| Code integrity checks are enforced. |
| .IP "\fB\-\-nxcompat\fR" 4 |
| .IX Item "--nxcompat" |
| The image is compatible with the Data Execution Prevention. |
| This feature was introduced with \s-1MS\s0 Windows \s-1XP\s0 \s-1SP2\s0 for i386 \s-1PE\s0 targets. |
| .IP "\fB\-\-no\-isolation\fR" 4 |
| .IX Item "--no-isolation" |
| Although the image understands isolation, do not isolate the image. |
| .IP "\fB\-\-no\-seh\fR" 4 |
| .IX Item "--no-seh" |
| The image does not use \s-1SEH\s0. No \s-1SE\s0 handler may be called from |
| this image. |
| .IP "\fB\-\-no\-bind\fR" 4 |
| .IX Item "--no-bind" |
| Do not bind this image. |
| .IP "\fB\-\-wdmdriver\fR" 4 |
| .IX Item "--wdmdriver" |
| The driver uses the \s-1MS\s0 Windows Driver Model. |
| .IP "\fB\-\-tsaware\fR" 4 |
| .IX Item "--tsaware" |
| The image is Terminal Server aware. |
| .PP |
| The C6X uClinux target uses a binary format called \s-1DSBT\s0 to support shared |
| libraries. Each shared library in the system needs to have a unique index; |
| all executables use an index of 0. |
| .IP "\fB\-\-dsbt\-size\fR \fIsize\fR" 4 |
| .IX Item "--dsbt-size size" |
| This option sets the number of entires in the \s-1DSBT\s0 of the current executable |
| or shared library to \fIsize\fR. The default is to create a table with 64 |
| entries. |
| .IP "\fB\-\-dsbt\-index\fR \fIindex\fR" 4 |
| .IX Item "--dsbt-index index" |
| This option sets the \s-1DSBT\s0 index of the current executable or shared library |
| to \fIindex\fR. The default is 0, which is appropriate for generating |
| executables. If a shared library is generated with a \s-1DSBT\s0 index of 0, the |
| \&\f(CW\*(C`R_C6000_DSBT_INDEX\*(C'\fR relocs are copied into the output file. |
| .Sp |
| The \fB\-\-no\-merge\-exidx\-entries\fR switch disables the merging of adjacent |
| exidx entries in frame unwind info. |
| .PP |
| The 68HC11 and 68HC12 linkers support specific options to control the |
| memory bank switching mapping and trampoline code generation. |
| .IP "\fB\-\-no\-trampoline\fR" 4 |
| .IX Item "--no-trampoline" |
| This option disables the generation of trampoline. By default a trampoline |
| is generated for each far function which is called using a \f(CW\*(C`jsr\*(C'\fR |
| instruction (this happens when a pointer to a far function is taken). |
| .IP "\fB\-\-bank\-window\fR \fIname\fR" 4 |
| .IX Item "--bank-window name" |
| This option indicates to the linker the name of the memory region in |
| the \fB\s-1MEMORY\s0\fR specification that describes the memory bank window. |
| The definition of such region is then used by the linker to compute |
| paging and addresses within the memory window. |
| .PP |
| The following options are supported to control handling of \s-1GOT\s0 generation |
| when linking for 68K targets. |
| .IP "\fB\-\-got=\fR\fItype\fR" 4 |
| .IX Item "--got=type" |
| This option tells the linker which \s-1GOT\s0 generation scheme to use. |
| \&\fItype\fR should be one of \fBsingle\fR, \fBnegative\fR, |
| \&\fBmultigot\fR or \fBtarget\fR. For more information refer to the |
| Info entry for \fIld\fR. |
| .SH "ENVIRONMENT" |
| .IX Header "ENVIRONMENT" |
| You can change the behaviour of \fBld\fR with the environment variables |
| \&\f(CW\*(C`GNUTARGET\*(C'\fR, |
| \&\f(CW\*(C`LDEMULATION\*(C'\fR and \f(CW\*(C`COLLECT_NO_DEMANGLE\*(C'\fR. |
| .PP |
| \&\f(CW\*(C`GNUTARGET\*(C'\fR determines the input-file object format if you don't |
| use \fB\-b\fR (or its synonym \fB\-\-format\fR). Its value should be one |
| of the \s-1BFD\s0 names for an input format. If there is no |
| \&\f(CW\*(C`GNUTARGET\*(C'\fR in the environment, \fBld\fR uses the natural format |
| of the target. If \f(CW\*(C`GNUTARGET\*(C'\fR is set to \f(CW\*(C`default\*(C'\fR then \s-1BFD\s0 |
| 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 specify |
| object-file formats is unique. However, the configuration procedure for |
| \&\s-1BFD\s0 on each system places the conventional format for that system first |
| in the search-list, so ambiguities are resolved in favor of convention. |
| .PP |
| \&\f(CW\*(C`LDEMULATION\*(C'\fR determines the default emulation if you don't use the |
| \&\fB\-m\fR option. The emulation can affect various aspects of linker |
| behaviour, particularly the default linker script. You can list the |
| available emulations with the \fB\-\-verbose\fR or \fB\-V\fR options. If |
| the \fB\-m\fR option is not used, and the \f(CW\*(C`LDEMULATION\*(C'\fR environment |
| variable is not defined, the default emulation depends upon how the |
| linker was configured. |
| .PP |
| Normally, the linker will default to demangling symbols. However, if |
| \&\f(CW\*(C`COLLECT_NO_DEMANGLE\*(C'\fR is set in the environment, then it will |
| default to not demangling symbols. This environment variable is used in |
| a similar fashion by the \f(CW\*(C`gcc\*(C'\fR linker wrapper program. The default |
| may be overridden by the \fB\-\-demangle\fR and \fB\-\-no\-demangle\fR |
| options. |
| .SH "SEE ALSO" |
| .IX Header "SEE ALSO" |
| \&\fIar\fR\|(1), \fInm\fR\|(1), \fIobjcopy\fR\|(1), \fIobjdump\fR\|(1), \fIreadelf\fR\|(1) and |
| the Info entries for \fIbinutils\fR and |
| \&\fIld\fR. |
| .SH "COPYRIGHT" |
| .IX Header "COPYRIGHT" |
| Copyright (c) 1991\-2013 Free Software Foundation, Inc. |
| .PP |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.3 |
| or any later version published by the Free 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 \*(L"\s-1GNU\s0 Free Documentation License\*(R". |
