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+<html lang="en">
+<head>
+<title>Installing GCC: Configuration</title>
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+<meta name="description" content="Installing GCC: Configuration">
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+(a) The FSF's Front-Cover Text is:
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+<body>
+<h1 class="settitle">Installing GCC: Configuration</h1>
+<a name="index-Configuration-1"></a><a name="index-Installing-GCC_003a-Configuration-2"></a>
+Like most GNU software, GCC must be configured before it can be built.
+This document describes the recommended configuration procedure
+for both native and cross targets.
+
+ <p>We use <var>srcdir</var> to refer to the toplevel source directory for
+GCC; we use <var>objdir</var> to refer to the toplevel build/object directory.
+
+ <p>If you obtained the sources via SVN, <var>srcdir</var> must refer to the top
+<samp><span class="file">gcc</span></samp> directory, the one where the <samp><span class="file">MAINTAINERS</span></samp> can be found,
+and not its <samp><span class="file">gcc</span></samp> subdirectory, otherwise the build will fail.
+
+ <p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS
+file system, the shell's built-in <samp><span class="command">pwd</span></samp> command will return
+temporary pathnames. Using these can lead to various sorts of build
+problems. To avoid this issue, set the <samp><span class="env">PWDCMD</span></samp> environment
+variable to an automounter-aware <samp><span class="command">pwd</span></samp> command, e.g.,
+<samp><span class="command">pawd</span></samp> or &lsquo;<samp><span class="samp">amq -w</span></samp>&rsquo;, during the configuration and build
+phases.
+
+ <p>First, we <strong>highly</strong> recommend that GCC be built into a
+separate directory than the sources which does <strong>not</strong> reside
+within the source tree. This is how we generally build GCC; building
+where <var>srcdir</var> == <var>objdir</var> should still work, but doesn't
+get extensive testing; building where <var>objdir</var> is a subdirectory
+of <var>srcdir</var> is unsupported.
+
+ <p>If you have previously built GCC in the same directory for a
+different target machine, do &lsquo;<samp><span class="samp">make distclean</span></samp>&rsquo; to delete all files
+that might be invalid. One of the files this deletes is <samp><span class="file">Makefile</span></samp>;
+if &lsquo;<samp><span class="samp">make distclean</span></samp>&rsquo; complains that <samp><span class="file">Makefile</span></samp> does not exist
+or issues a message like &ldquo;don't know how to make distclean&rdquo; it probably
+means that the directory is already suitably clean. However, with the
+recommended method of building in a separate <var>objdir</var>, you should
+simply use a different <var>objdir</var> for each target.
+
+ <p>Second, when configuring a native system, either <samp><span class="command">cc</span></samp> or
+<samp><span class="command">gcc</span></samp> must be in your path or you must set <samp><span class="env">CC</span></samp> in
+your environment before running configure. Otherwise the configuration
+scripts may fail.
+
+ <p>To configure GCC:
+
+<pre class="smallexample"> % mkdir <var>objdir</var>
+ % cd <var>objdir</var>
+ % <var>srcdir</var>/configure [<var>options</var>] [<var>target</var>]
+</pre>
+ <h3 class="heading"><a name="TOC0"></a>Distributor options</h3>
+
+<p>If you will be distributing binary versions of GCC, with modifications
+to the source code, you should use the options described in this
+section to make clear that your version contains modifications.
+
+ <dl>
+<dt><code>--with-pkgversion=</code><var>version</var><dd>Specify a string that identifies your package. You may wish
+to include a build number or build date. This version string will be
+included in the output of <samp><span class="command">gcc --version</span></samp>. This suffix does
+not replace the default version string, only the &lsquo;<samp><span class="samp">GCC</span></samp>&rsquo; part.
+
+ <p>The default value is &lsquo;<samp><span class="samp">GCC</span></samp>&rsquo;.
+
+ <br><dt><code>--with-bugurl=</code><var>url</var><dd>Specify the URL that users should visit if they wish to report a bug.
+You are of course welcome to forward bugs reported to you to the FSF,
+if you determine that they are not bugs in your modifications.
+
+ <p>The default value refers to the FSF's GCC bug tracker.
+
+ </dl>
+
+<h3 class="heading"><a name="TOC1"></a>Target specification</h3>
+
+ <ul>
+<li>GCC has code to correctly determine the correct value for <var>target</var>
+for nearly all native systems. Therefore, we highly recommend you not
+provide a configure target when configuring a native compiler.
+
+ <li><var>target</var> must be specified as <samp><span class="option">--target=</span><var>target</var></samp>
+when configuring a cross compiler; examples of valid targets would be
+m68k-coff, sh-elf, etc.
+
+ <li>Specifying just <var>target</var> instead of <samp><span class="option">--target=</span><var>target</var></samp>
+implies that the host defaults to <var>target</var>.
+</ul>
+
+<h3 class="heading"><a name="TOC2"></a>Options specification</h3>
+
+<p>Use <var>options</var> to override several configure time options for
+GCC. A list of supported <var>options</var> follows; &lsquo;<samp><span class="samp">configure
+--help</span></samp>&rsquo; may list other options, but those not listed below may not
+work and should not normally be used.
+
+ <p>Note that each <samp><span class="option">--enable</span></samp> option has a corresponding
+<samp><span class="option">--disable</span></samp> option and that each <samp><span class="option">--with</span></samp> option has a
+corresponding <samp><span class="option">--without</span></samp> option.
+
+ <dl>
+<dt><code>--prefix=</code><var>dirname</var><dd>Specify the toplevel installation
+directory. This is the recommended way to install the tools into a directory
+other than the default. The toplevel installation directory defaults to
+<samp><span class="file">/usr/local</span></samp>.
+
+ <p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a
+subdirectory of <var>objdir</var> or vice versa. If specifying a directory
+beneath a user's home directory tree, some shells will not expand
+<var>dirname</var> correctly if it contains the &lsquo;<samp><span class="samp">~</span></samp>&rsquo; metacharacter; use
+<samp><span class="env">$HOME</span></samp> instead.
+
+ <p>The following standard <samp><span class="command">autoconf</span></samp> options are supported. Normally you
+should not need to use these options.
+ <dl>
+<dt><code>--exec-prefix=</code><var>dirname</var><dd>Specify the toplevel installation directory for architecture-dependent
+files. The default is <samp><var>prefix</var></samp>.
+
+ <br><dt><code>--bindir=</code><var>dirname</var><dd>Specify the installation directory for the executables called by users
+(such as <samp><span class="command">gcc</span></samp> and <samp><span class="command">g++</span></samp>). The default is
+<samp><var>exec-prefix</var><span class="file">/bin</span></samp>.
+
+ <br><dt><code>--libdir=</code><var>dirname</var><dd>Specify the installation directory for object code libraries and
+internal data files of GCC. The default is <samp><var>exec-prefix</var><span class="file">/lib</span></samp>.
+
+ <br><dt><code>--libexecdir=</code><var>dirname</var><dd>Specify the installation directory for internal executables of GCC.
+ The default is <samp><var>exec-prefix</var><span class="file">/libexec</span></samp>.
+
+ <br><dt><code>--with-slibdir=</code><var>dirname</var><dd>Specify the installation directory for the shared libgcc library. The
+default is <samp><var>libdir</var></samp>.
+
+ <br><dt><code>--infodir=</code><var>dirname</var><dd>Specify the installation directory for documentation in info format.
+The default is <samp><var>prefix</var><span class="file">/info</span></samp>.
+
+ <br><dt><code>--datadir=</code><var>dirname</var><dd>Specify the installation directory for some architecture-independent
+data files referenced by GCC. The default is <samp><var>prefix</var><span class="file">/share</span></samp>.
+
+ <br><dt><code>--mandir=</code><var>dirname</var><dd>Specify the installation directory for manual pages. The default is
+<samp><var>prefix</var><span class="file">/man</span></samp>. (Note that the manual pages are only extracts from
+the full GCC manuals, which are provided in Texinfo format. The manpages
+are derived by an automatic conversion process from parts of the full
+manual.)
+
+ <br><dt><code>--with-gxx-include-dir=</code><var>dirname</var><dd>Specify
+the installation directory for G++ header files. The default is
+<samp><var>prefix</var><span class="file">/include/c++/</span><var>version</var></samp>.
+
+ </dl>
+
+ <br><dt><code>--program-prefix=</code><var>prefix</var><dd>GCC supports some transformations of the names of its programs when
+installing them. This option prepends <var>prefix</var> to the names of
+programs to install in <var>bindir</var> (see above). For example, specifying
+<samp><span class="option">--program-prefix=foo-</span></samp> would result in &lsquo;<samp><span class="samp">gcc</span></samp>&rsquo;
+being installed as <samp><span class="file">/usr/local/bin/foo-gcc</span></samp>.
+
+ <br><dt><code>--program-suffix=</code><var>suffix</var><dd>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var>
+(see above). For example, specifying <samp><span class="option">--program-suffix=-3.1</span></samp>
+would result in &lsquo;<samp><span class="samp">gcc</span></samp>&rsquo; being installed as
+<samp><span class="file">/usr/local/bin/gcc-3.1</span></samp>.
+
+ <br><dt><code>--program-transform-name=</code><var>pattern</var><dd>Applies the &lsquo;<samp><span class="samp">sed</span></samp>&rsquo; script <var>pattern</var> to be applied to the names
+of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to
+consist of one or more basic &lsquo;<samp><span class="samp">sed</span></samp>&rsquo; editing commands, separated by
+semicolons. For example, if you want the &lsquo;<samp><span class="samp">gcc</span></samp>&rsquo; program name to be
+transformed to the installed program <samp><span class="file">/usr/local/bin/myowngcc</span></samp> and
+the &lsquo;<samp><span class="samp">g++</span></samp>&rsquo; program name to be transformed to
+<samp><span class="file">/usr/local/bin/gspecial++</span></samp> without changing other program names,
+you could use the pattern
+<samp><span class="option">--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</span></samp>
+to achieve this effect.
+
+ <p>All three options can be combined and used together, resulting in more
+complex conversion patterns. As a basic rule, <var>prefix</var> (and
+<var>suffix</var>) are prepended (appended) before further transformations
+can happen with a special transformation script <var>pattern</var>.
+
+ <p>As currently implemented, this option only takes effect for native
+builds; cross compiler binaries' names are not transformed even when a
+transformation is explicitly asked for by one of these options.
+
+ <p>For native builds, some of the installed programs are also installed
+with the target alias in front of their name, as in
+&lsquo;<samp><span class="samp">i686-pc-linux-gnu-gcc</span></samp>&rsquo;. All of the above transformations happen
+before the target alias is prepended to the name&mdash;so, specifying
+<samp><span class="option">--program-prefix=foo-</span></samp> and <samp><span class="option">program-suffix=-3.1</span></samp>, the
+resulting binary would be installed as
+<samp><span class="file">/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</span></samp>.
+
+ <p>As a last shortcoming, none of the installed Ada programs are
+transformed yet, which will be fixed in some time.
+
+ <br><dt><code>--with-local-prefix=</code><var>dirname</var><dd>Specify the
+installation directory for local include files. The default is
+<samp><span class="file">/usr/local</span></samp>. Specify this option if you want the compiler to
+search directory <samp><var>dirname</var><span class="file">/include</span></samp> for locally installed
+header files <em>instead</em> of <samp><span class="file">/usr/local/include</span></samp>.
+
+ <p>You should specify <samp><span class="option">--with-local-prefix</span></samp> <strong>only</strong> if your
+site has a different convention (not <samp><span class="file">/usr/local</span></samp>) for where to put
+site-specific files.
+
+ <p>The default value for <samp><span class="option">--with-local-prefix</span></samp> is <samp><span class="file">/usr/local</span></samp>
+regardless of the value of <samp><span class="option">--prefix</span></samp>. Specifying
+<samp><span class="option">--prefix</span></samp> has no effect on which directory GCC searches for
+local header files. This may seem counterintuitive, but actually it is
+logical.
+
+ <p>The purpose of <samp><span class="option">--prefix</span></samp> is to specify where to <em>install
+GCC</em>. The local header files in <samp><span class="file">/usr/local/include</span></samp>&mdash;if you put
+any in that directory&mdash;are not part of GCC. They are part of other
+programs&mdash;perhaps many others. (GCC installs its own header files in
+another directory which is based on the <samp><span class="option">--prefix</span></samp> value.)
+
+ <p>Both the local-prefix include directory and the GCC-prefix include
+directory are part of GCC's &ldquo;system include&rdquo; directories. Although these
+two directories are not fixed, they need to be searched in the proper
+order for the correct processing of the include_next directive. The
+local-prefix include directory is searched before the GCC-prefix
+include directory. Another characteristic of system include directories
+is that pedantic warnings are turned off for headers in these directories.
+
+ <p>Some autoconf macros add <samp><span class="option">-I </span><var>directory</var></samp> options to the
+compiler command line, to ensure that directories containing installed
+packages' headers are searched. When <var>directory</var> is one of GCC's
+system include directories, GCC will ignore the option so that system
+directories continue to be processed in the correct order. This
+may result in a search order different from what was specified but the
+directory will still be searched.
+
+ <p>GCC automatically searches for ordinary libraries using
+<samp><span class="env">GCC_EXEC_PREFIX</span></samp>. Thus, when the same installation prefix is
+used for both GCC and packages, GCC will automatically search for
+both headers and libraries. This provides a configuration that is
+easy to use. GCC behaves in a manner similar to that when it is
+installed as a system compiler in <samp><span class="file">/usr</span></samp>.
+
+ <p>Sites that need to install multiple versions of GCC may not want to
+use the above simple configuration. It is possible to use the
+<samp><span class="option">--program-prefix</span></samp>, <samp><span class="option">--program-suffix</span></samp> and
+<samp><span class="option">--program-transform-name</span></samp> options to install multiple versions
+into a single directory, but it may be simpler to use different prefixes
+and the <samp><span class="option">--with-local-prefix</span></samp> option to specify the location of the
+site-specific files for each version. It will then be necessary for
+users to specify explicitly the location of local site libraries
+(e.g., with <samp><span class="env">LIBRARY_PATH</span></samp>).
+
+ <p>The same value can be used for both <samp><span class="option">--with-local-prefix</span></samp> and
+<samp><span class="option">--prefix</span></samp> provided it is not <samp><span class="file">/usr</span></samp>. This can be used
+to avoid the default search of <samp><span class="file">/usr/local/include</span></samp>.
+
+ <p><strong>Do not</strong> specify <samp><span class="file">/usr</span></samp> as the <samp><span class="option">--with-local-prefix</span></samp>!
+The directory you use for <samp><span class="option">--with-local-prefix</span></samp> <strong>must not</strong>
+contain any of the system's standard header files. If it did contain
+them, certain programs would be miscompiled (including GNU Emacs, on
+certain targets), because this would override and nullify the header
+file corrections made by the <samp><span class="command">fixincludes</span></samp> script.
+
+ <p>Indications are that people who use this option use it based on mistaken
+ideas of what it is for. People use it as if it specified where to
+install part of GCC. Perhaps they make this assumption because
+installing GCC creates the directory.
+
+ <br><dt><code>--enable-shared[=</code><var>package</var><code>[,...]]</code><dd>Build shared versions of libraries, if shared libraries are supported on
+the target platform. Unlike GCC 2.95.x and earlier, shared libraries
+are enabled by default on all platforms that support shared libraries.
+
+ <p>If a list of packages is given as an argument, build shared libraries
+only for the listed packages. For other packages, only static libraries
+will be built. Package names currently recognized in the GCC tree are
+&lsquo;<samp><span class="samp">libgcc</span></samp>&rsquo; (also known as &lsquo;<samp><span class="samp">gcc</span></samp>&rsquo;), &lsquo;<samp><span class="samp">libstdc++</span></samp>&rsquo; (not
+&lsquo;<samp><span class="samp">libstdc++-v3</span></samp>&rsquo;), &lsquo;<samp><span class="samp">libffi</span></samp>&rsquo;, &lsquo;<samp><span class="samp">zlib</span></samp>&rsquo;, &lsquo;<samp><span class="samp">boehm-gc</span></samp>&rsquo;,
+&lsquo;<samp><span class="samp">ada</span></samp>&rsquo;, &lsquo;<samp><span class="samp">libada</span></samp>&rsquo;, &lsquo;<samp><span class="samp">libjava</span></samp>&rsquo; and &lsquo;<samp><span class="samp">libobjc</span></samp>&rsquo;.
+Note &lsquo;<samp><span class="samp">libiberty</span></samp>&rsquo; does not support shared libraries at all.
+
+ <p>Use <samp><span class="option">--disable-shared</span></samp> to build only static libraries. Note that
+<samp><span class="option">--disable-shared</span></samp> does not accept a list of package names as
+argument, only <samp><span class="option">--enable-shared</span></samp> does.
+
+ <br><dt><code><a name="with_002dgnu_002das"></a>--with-gnu-as</code><dd>Specify that the compiler should assume that the
+assembler it finds is the GNU assembler. However, this does not modify
+the rules to find an assembler and will result in confusion if the
+assembler found is not actually the GNU assembler. (Confusion may also
+result if the compiler finds the GNU assembler but has not been
+configured with <samp><span class="option">--with-gnu-as</span></samp>.) If you have more than one
+assembler installed on your system, you may want to use this option in
+connection with <samp><span class="option">--with-as=</span><var>pathname</var></samp> or
+<samp><span class="option">--with-build-time-tools=</span><var>pathname</var></samp>.
+
+ <p>The following systems are the only ones where it makes a difference
+whether you use the GNU assembler. On any other system,
+<samp><span class="option">--with-gnu-as</span></samp> has no effect.
+
+ <ul>
+<li>&lsquo;<samp><span class="samp">hppa1.0-</span><var>any</var><span class="samp">-</span><var>any</var></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">hppa1.1-</span><var>any</var><span class="samp">-</span><var>any</var></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">i386-</span><var>any</var><span class="samp">-sysv</span></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">m68k-bull-sysv</span></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">m68k-hp-hpux</span></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">m68000-hp-hpux</span></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">m68000-att-sysv</span></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">sparc-sun-solaris2.</span><var>any</var></samp>&rsquo;
+<li>&lsquo;<samp><span class="samp">sparc64-</span><var>any</var><span class="samp">-solaris2.</span><var>any</var></samp>&rsquo;
+</ul>
+
+ <p>On the systems listed above (except for the HP-PA, the SPARC, for ISC on
+the 386, if you use the GNU assembler, you should also use the GNU linker
+(and specify <samp><span class="option">--with-gnu-ld</span></samp>).
+
+ <br><dt><code><a name="with_002das"></a>--with-as=</code><var>pathname</var><dd>Specify that the compiler should use the assembler pointed to by
+<var>pathname</var>, rather than the one found by the standard rules to find
+an assembler, which are:
+ <ul>
+<li>Unless GCC is being built with a cross compiler, check the
+<samp><var>libexec</var><span class="file">/gcc/</span><var>target</var><span class="file">/</span><var>version</var></samp> directory.
+<var>libexec</var> defaults to <samp><var>exec-prefix</var><span class="file">/libexec</span></samp>;
+<var>exec-prefix</var> defaults to <var>prefix</var>, which
+defaults to <samp><span class="file">/usr/local</span></samp> unless overridden by the
+<samp><span class="option">--prefix=</span><var>pathname</var></samp> switch described above. <var>target</var>
+is the target system triple, such as &lsquo;<samp><span class="samp">sparc-sun-solaris2.7</span></samp>&rsquo;, and
+<var>version</var> denotes the GCC version, such as 3.0.
+
+ <li>If the target system is the same that you are building on, check
+operating system specific directories (e.g. <samp><span class="file">/usr/ccs/bin</span></samp> on
+Sun Solaris 2).
+
+ <li>Check in the <samp><span class="env">PATH</span></samp> for a tool whose name is prefixed by the
+target system triple.
+
+ <li>Check in the <samp><span class="env">PATH</span></samp> for a tool whose name is not prefixed by the
+target system triple, if the host and target system triple are
+the same (in other words, we use a host tool if it can be used for
+the target as well).
+</ul>
+
+ <p>You may want to use <samp><span class="option">--with-as</span></samp> if no assembler
+is installed in the directories listed above, or if you have multiple
+assemblers installed and want to choose one that is not found by the
+above rules.
+
+ <br><dt><code><a name="with_002dgnu_002dld"></a>--with-gnu-ld</code><dd>Same as <a href="#with-gnu-as"><samp><span class="option">--with-gnu-as</span></samp></a>
+but for the linker.
+
+ <br><dt><code>--with-ld=</code><var>pathname</var><dd>Same as <a href="#with-as"><samp><span class="option">--with-as</span></samp></a>
+but for the linker.
+
+ <br><dt><code>--with-stabs</code><dd>Specify that stabs debugging
+information should be used instead of whatever format the host normally
+uses. Normally GCC uses the same debug format as the host system.
+
+ <p>On MIPS based systems and on Alphas, you must specify whether you want
+GCC to create the normal ECOFF debugging format, or to use BSD-style
+stabs passed through the ECOFF symbol table. The normal ECOFF debug
+format cannot fully handle languages other than C. BSD stabs format can
+handle other languages, but it only works with the GNU debugger GDB.
+
+ <p>Normally, GCC uses the ECOFF debugging format by default; if you
+prefer BSD stabs, specify <samp><span class="option">--with-stabs</span></samp> when you configure GCC.
+
+ <p>No matter which default you choose when you configure GCC, the user
+can use the <samp><span class="option">-gcoff</span></samp> and <samp><span class="option">-gstabs+</span></samp> options to specify explicitly
+the debug format for a particular compilation.
+
+ <p><samp><span class="option">--with-stabs</span></samp> is meaningful on the ISC system on the 386, also, if
+<samp><span class="option">--with-gas</span></samp> is used. It selects use of stabs debugging
+information embedded in COFF output. This kind of debugging information
+supports C++ well; ordinary COFF debugging information does not.
+
+ <p><samp><span class="option">--with-stabs</span></samp> is also meaningful on 386 systems running SVR4. It
+selects use of stabs debugging information embedded in ELF output. The
+C++ compiler currently (2.6.0) does not support the DWARF debugging
+information normally used on 386 SVR4 platforms; stabs provide a
+workable alternative. This requires gas and gdb, as the normal SVR4
+tools can not generate or interpret stabs.
+
+ <br><dt><code>--disable-multilib</code><dd>Specify that multiple target
+libraries to support different target variants, calling
+conventions, etc. should not be built. The default is to build a
+predefined set of them.
+
+ <p>Some targets provide finer-grained control over which multilibs are built
+(e.g., <samp><span class="option">--disable-softfloat</span></samp>):
+ <dl>
+<dt><code>arc-*-elf*</code><dd>biendian.
+
+ <br><dt><code>arm-*-*</code><dd>fpu, 26bit, underscore, interwork, biendian, nofmult.
+
+ <br><dt><code>m68*-*-*</code><dd>softfloat, m68881, m68000, m68020.
+
+ <br><dt><code>mips*-*-*</code><dd>single-float, biendian, softfloat.
+
+ <br><dt><code>powerpc*-*-*, rs6000*-*-*</code><dd>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian,
+sysv, aix.
+
+ </dl>
+
+ <br><dt><code>--enable-threads</code><dd>Specify that the target
+supports threads. This affects the Objective-C compiler and runtime
+library, and exception handling for other languages like C++ and Java.
+On some systems, this is the default.
+
+ <p>In general, the best (and, in many cases, the only known) threading
+model available will be configured for use. Beware that on some
+systems, GCC has not been taught what threading models are generally
+available for the system. In this case, <samp><span class="option">--enable-threads</span></samp> is an
+alias for <samp><span class="option">--enable-threads=single</span></samp>.
+
+ <br><dt><code>--disable-threads</code><dd>Specify that threading support should be disabled for the system.
+This is an alias for <samp><span class="option">--enable-threads=single</span></samp>.
+
+ <br><dt><code>--enable-threads=</code><var>lib</var><dd>Specify that
+<var>lib</var> is the thread support library. This affects the Objective-C
+compiler and runtime library, and exception handling for other languages
+like C++ and Java. The possibilities for <var>lib</var> are:
+
+ <dl>
+<dt><code>aix</code><dd>AIX thread support.
+<br><dt><code>dce</code><dd>DCE thread support.
+<br><dt><code>gnat</code><dd>Ada tasking support. For non-Ada programs, this setting is equivalent
+to &lsquo;<samp><span class="samp">single</span></samp>&rsquo;. When used in conjunction with the Ada run time, it
+causes GCC to use the same thread primitives as Ada uses. This option
+is necessary when using both Ada and the back end exception handling,
+which is the default for most Ada targets.
+<br><dt><code>mach</code><dd>Generic MACH thread support, known to work on NeXTSTEP. (Please note
+that the file needed to support this configuration, <samp><span class="file">gthr-mach.h</span></samp>, is
+missing and thus this setting will cause a known bootstrap failure.)
+<br><dt><code>no</code><dd>This is an alias for &lsquo;<samp><span class="samp">single</span></samp>&rsquo;.
+<br><dt><code>posix</code><dd>Generic POSIX/Unix98 thread support.
+<br><dt><code>posix95</code><dd>Generic POSIX/Unix95 thread support.
+<br><dt><code>rtems</code><dd>RTEMS thread support.
+<br><dt><code>single</code><dd>Disable thread support, should work for all platforms.
+<br><dt><code>solaris</code><dd>Sun Solaris 2 thread support.
+<br><dt><code>vxworks</code><dd>VxWorks thread support.
+<br><dt><code>win32</code><dd>Microsoft Win32 API thread support.
+<br><dt><code>nks</code><dd>Novell Kernel Services thread support.
+</dl>
+
+ <br><dt><code>--enable-tls</code><dd>Specify that the target supports TLS (Thread Local Storage). Usually
+configure can correctly determine if TLS is supported. In cases where
+it guesses incorrectly, TLS can be explicitly enabled or disabled with
+<samp><span class="option">--enable-tls</span></samp> or <samp><span class="option">--disable-tls</span></samp>. This can happen if
+the assembler supports TLS but the C library does not, or if the
+assumptions made by the configure test are incorrect.
+
+ <br><dt><code>--disable-tls</code><dd>Specify that the target does not support TLS.
+This is an alias for <samp><span class="option">--enable-tls=no</span></samp>.
+
+ <br><dt><code>--with-cpu=</code><var>cpu</var><dd>Specify which cpu variant the compiler should generate code for by default.
+<var>cpu</var> will be used as the default value of the <samp><span class="option">-mcpu=</span></samp> switch.
+This option is only supported on some targets, including ARM, i386, M68k,
+PowerPC, and SPARC.
+
+ <br><dt><code>--with-schedule=</code><var>cpu</var><dt><code>--with-arch=</code><var>cpu</var><dt><code>--with-tune=</code><var>cpu</var><dt><code>--with-abi=</code><var>abi</var><dt><code>--with-fpu=</code><var>type</var><dt><code>--with-float=</code><var>type</var><dd>These configure options provide default values for the <samp><span class="option">-mschedule=</span></samp>,
+<samp><span class="option">-march=</span></samp>, <samp><span class="option">-mtune=</span></samp>, <samp><span class="option">-mabi=</span></samp>, and <samp><span class="option">-mfpu=</span></samp>
+options and for <samp><span class="option">-mhard-float</span></samp> or <samp><span class="option">-msoft-float</span></samp>. As with
+<samp><span class="option">--with-cpu</span></samp>, which switches will be accepted and acceptable values
+of the arguments depend on the target.
+
+ <br><dt><code>--with-mode=</code><var>mode</var><dd>Specify if the compiler should default to <samp><span class="option">-marm</span></samp> or <samp><span class="option">-mthumb</span></samp>.
+This option is only supported on ARM targets.
+
+ <br><dt><code>--with-divide=</code><var>type</var><dd>Specify how the compiler should generate code for checking for
+division by zero. This option is only supported on the MIPS target.
+The possibilities for <var>type</var> are:
+ <dl>
+<dt><code>traps</code><dd>Division by zero checks use conditional traps (this is the default on
+systems that support conditional traps).
+<br><dt><code>breaks</code><dd>Division by zero checks use the break instruction.
+</dl>
+
+ <!-- If you make -with-llsc the default for additional targets, -->
+ <!-- update the -with-llsc description in the MIPS section below. -->
+ <br><dt><code>--with-llsc</code><dd>On MIPS targets, make <samp><span class="option">-mllsc</span></samp> the default when no
+<samp><span class="option">-mno-lsc</span></samp> option is passed. This is the default for
+Linux-based targets, as the kernel will emulate them if the ISA does
+not provide them.
+
+ <br><dt><code>--without-llsc</code><dd>On MIPS targets, make <samp><span class="option">-mno-llsc</span></samp> the default when no
+<samp><span class="option">-mllsc</span></samp> option is passed.
+
+ <br><dt><code>--enable-__cxa_atexit</code><dd>Define if you want to use __cxa_atexit, rather than atexit, to
+register C++ destructors for local statics and global objects.
+This is essential for fully standards-compliant handling of
+destructors, but requires __cxa_atexit in libc. This option is currently
+only available on systems with GNU libc. When enabled, this will cause
+<samp><span class="option">-fuse-cxa-atexit</span></samp> to be passed by default.
+
+ <br><dt><code>--enable-target-optspace</code><dd>Specify that target
+libraries should be optimized for code space instead of code speed.
+This is the default for the m32r platform.
+
+ <br><dt><code>--disable-cpp</code><dd>Specify that a user visible <samp><span class="command">cpp</span></samp> program should not be installed.
+
+ <br><dt><code>--with-cpp-install-dir=</code><var>dirname</var><dd>Specify that the user visible <samp><span class="command">cpp</span></samp> program should be installed
+in <samp><var>prefix</var><span class="file">/</span><var>dirname</var><span class="file">/cpp</span></samp>, in addition to <var>bindir</var>.
+
+ <br><dt><code>--enable-initfini-array</code><dd>Force the use of sections <code>.init_array</code> and <code>.fini_array</code>
+(instead of <code>.init</code> and <code>.fini</code>) for constructors and
+destructors. Option <samp><span class="option">--disable-initfini-array</span></samp> has the
+opposite effect. If neither option is specified, the configure script
+will try to guess whether the <code>.init_array</code> and
+<code>.fini_array</code> sections are supported and, if they are, use them.
+
+ <br><dt><code>--enable-maintainer-mode</code><dd>The build rules that
+regenerate the GCC master message catalog <samp><span class="file">gcc.pot</span></samp> are normally
+disabled. This is because it can only be rebuilt if the complete source
+tree is present. If you have changed the sources and want to rebuild the
+catalog, configuring with <samp><span class="option">--enable-maintainer-mode</span></samp> will enable
+this. Note that you need a recent version of the <code>gettext</code> tools
+to do so.
+
+ <br><dt><code>--disable-bootstrap</code><dd>For a native build, the default configuration is to perform
+a 3-stage bootstrap of the compiler when &lsquo;<samp><span class="samp">make</span></samp>&rsquo; is invoked,
+testing that GCC can compile itself correctly. If you want to disable
+this process, you can configure with <samp><span class="option">--disable-bootstrap</span></samp>.
+
+ <br><dt><code>--enable-bootstrap</code><dd>In special cases, you may want to perform a 3-stage build
+even if the target and host triplets are different.
+This could happen when the host can run code compiled for
+the target (e.g. host is i686-linux, target is i486-linux).
+Starting from GCC 4.2, to do this you have to configure explicitly
+with <samp><span class="option">--enable-bootstrap</span></samp>.
+
+ <br><dt><code>--enable-generated-files-in-srcdir</code><dd>Neither the .c and .h files that are generated from Bison and flex nor the
+info manuals and man pages that are built from the .texi files are present
+in the SVN development tree. When building GCC from that development tree,
+or from one of our snapshots, those generated files are placed in your
+build directory, which allows for the source to be in a readonly
+directory.
+
+ <p>If you configure with <samp><span class="option">--enable-generated-files-in-srcdir</span></samp> then those
+generated files will go into the source directory. This is mainly intended
+for generating release or prerelease tarballs of the GCC sources, since it
+is not a requirement that the users of source releases to have flex, Bison,
+or makeinfo.
+
+ <br><dt><code>--enable-version-specific-runtime-libs</code><dd>Specify
+that runtime libraries should be installed in the compiler specific
+subdirectory (<samp><var>libdir</var><span class="file">/gcc</span></samp>) rather than the usual places. In
+addition, &lsquo;<samp><span class="samp">libstdc++</span></samp>&rsquo;'s include files will be installed into
+<samp><var>libdir</var></samp> unless you overruled it by using
+<samp><span class="option">--with-gxx-include-dir=</span><var>dirname</var></samp>. Using this option is
+particularly useful if you intend to use several versions of GCC in
+parallel. This is currently supported by &lsquo;<samp><span class="samp">libgfortran</span></samp>&rsquo;,
+&lsquo;<samp><span class="samp">libjava</span></samp>&rsquo;, &lsquo;<samp><span class="samp">libmudflap</span></samp>&rsquo;, &lsquo;<samp><span class="samp">libstdc++</span></samp>&rsquo;, and &lsquo;<samp><span class="samp">libobjc</span></samp>&rsquo;.
+
+ <br><dt><code>--enable-languages=</code><var>lang1</var><code>,</code><var>lang2</var><code>,...</code><dd>Specify that only a particular subset of compilers and
+their runtime libraries should be built. For a list of valid values for
+<var>langN</var> you can issue the following command in the
+<samp><span class="file">gcc</span></samp> directory of your GCC source tree:<br>
+ <pre class="smallexample"> grep language= */config-lang.in
+</pre>
+ <p>Currently, you can use any of the following:
+<code>all</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>fortran</code>, <code>java</code>,
+<code>objc</code>, <code>obj-c++</code>, <code>treelang</code>.
+Building the Ada compiler has special requirements, see below.
+If you do not pass this flag, or specify the option <code>all</code>, then all
+default languages available in the <samp><span class="file">gcc</span></samp> sub-tree will be configured.
+Ada, Objective-C++, and treelang are not default languages; the rest are.
+Re-defining <code>LANGUAGES</code> when calling &lsquo;<samp><span class="samp">make</span></samp>&rsquo; <strong>does not</strong>
+work anymore, as those language sub-directories might not have been
+configured!
+
+ <br><dt><code>--enable-stage1-languages=</code><var>lang1</var><code>,</code><var>lang2</var><code>,...</code><dd>Specify that a particular subset of compilers and their runtime
+libraries should be built with the system C compiler during stage 1 of
+the bootstrap process, rather than only in later stages with the
+bootstrapped C compiler. The list of valid values is the same as for
+<samp><span class="option">--enable-languages</span></samp>, and the option <code>all</code> will select all
+of the languages enabled by <samp><span class="option">--enable-languages</span></samp>. This option is
+primarily useful for GCC development; for instance, when a development
+version of the compiler cannot bootstrap due to compiler bugs, or when
+one is debugging front ends other than the C front end. When this
+option is used, one can then build the target libraries for the
+specified languages with the stage-1 compiler by using <samp><span class="command">make
+stage1-bubble all-target</span></samp>, or run the testsuite on the stage-1 compiler
+for the specified languages using <samp><span class="command">make stage1-start check-gcc</span></samp>.
+
+ <br><dt><code>--disable-libada</code><dd>Specify that the run-time libraries and tools used by GNAT should not
+be built. This can be useful for debugging, or for compatibility with
+previous Ada build procedures, when it was required to explicitly
+do a &lsquo;<samp><span class="samp">make -C gcc gnatlib_and_tools</span></samp>&rsquo;.
+
+ <br><dt><code>--disable-libssp</code><dd>Specify that the run-time libraries for stack smashing protection
+should not be built.
+
+ <br><dt><code>--disable-libgomp</code><dd>Specify that the run-time libraries used by GOMP should not be built.
+
+ <br><dt><code>--with-dwarf2</code><dd>Specify that the compiler should
+use DWARF 2 debugging information as the default.
+
+ <br><dt><code>--enable-targets=all</code><dt><code>--enable-targets=</code><var>target_list</var><dd>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers.
+These are compilers that are able to generate either 64-bit or 32-bit
+code. Typically, the corresponding 32-bit target, e.g.
+powerpc-linux for powerpc64-linux, only generates 32-bit code. This
+option enables the 32-bit target to be a bi-arch compiler, which is
+useful when you want a bi-arch compiler that defaults to 32-bit, and
+you are building a bi-arch or multi-arch binutils in a combined tree.
+Currently, this option only affects powerpc-linux and x86-linux.
+
+ <br><dt><code>--enable-secureplt</code><dd>This option enables <samp><span class="option">-msecure-plt</span></samp> by default for powerpc-linux.
+See &ldquo;RS/6000 and PowerPC Options&rdquo; in the main manual
+
+ <br><dt><code>--enable-cld</code><dd>This option enables <samp><span class="option">-mcld</span></samp> by default for 32-bit x86 targets.
+See &ldquo;i386 and x86-64 Options&rdquo; in the main manual
+
+ <br><dt><code>--enable-win32-registry</code><dt><code>--enable-win32-registry=</code><var>key</var><dt><code>--disable-win32-registry</code><dd>The <samp><span class="option">--enable-win32-registry</span></samp> option enables Microsoft Windows-hosted GCC
+to look up installations paths in the registry using the following key:
+
+ <pre class="smallexample"> <code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\</code><var>key</var>
+</pre>
+ <p><var>key</var> defaults to GCC version number, and can be overridden by the
+<samp><span class="option">--enable-win32-registry=</span><var>key</var></samp> option. Vendors and distributors
+who use custom installers are encouraged to provide a different key,
+perhaps one comprised of vendor name and GCC version number, to
+avoid conflict with existing installations. This feature is enabled
+by default, and can be disabled by <samp><span class="option">--disable-win32-registry</span></samp>
+option. This option has no effect on the other hosts.
+
+ <br><dt><code>--nfp</code><dd>Specify that the machine does not have a floating point unit. This
+option only applies to &lsquo;<samp><span class="samp">m68k-sun-sunos</span><var>n</var></samp>&rsquo;. On any other
+system, <samp><span class="option">--nfp</span></samp> has no effect.
+
+ <br><dt><code>--enable-werror</code><dt><code>--disable-werror</code><dt><code>--enable-werror=yes</code><dt><code>--enable-werror=no</code><dd>When you specify this option, it controls whether certain files in the
+compiler are built with <samp><span class="option">-Werror</span></samp> in bootstrap stage2 and later.
+If you don't specify it, <samp><span class="option">-Werror</span></samp> is turned on for the main
+development trunk. However it defaults to off for release branches and
+final releases. The specific files which get <samp><span class="option">-Werror</span></samp> are
+controlled by the Makefiles.
+
+ <br><dt><code>--enable-checking</code><dt><code>--enable-checking=</code><var>list</var><dd>When you specify this option, the compiler is built to perform internal
+consistency checks of the requested complexity. This does not change the
+generated code, but adds error checking within the compiler. This will
+slow down the compiler and may only work properly if you are building
+the compiler with GCC. This is &lsquo;<samp><span class="samp">yes</span></samp>&rsquo; by default when building
+from SVN or snapshots, but &lsquo;<samp><span class="samp">release</span></samp>&rsquo; for releases. More control
+over the checks may be had by specifying <var>list</var>. The categories of
+checks available are &lsquo;<samp><span class="samp">yes</span></samp>&rsquo; (most common checks
+&lsquo;<samp><span class="samp">assert,misc,tree,gc,rtlflag,runtime</span></samp>&rsquo;), &lsquo;<samp><span class="samp">no</span></samp>&rsquo; (no checks at
+all), &lsquo;<samp><span class="samp">all</span></samp>&rsquo; (all but &lsquo;<samp><span class="samp">valgrind</span></samp>&rsquo;), &lsquo;<samp><span class="samp">release</span></samp>&rsquo; (cheapest
+checks &lsquo;<samp><span class="samp">assert,runtime</span></samp>&rsquo;) or &lsquo;<samp><span class="samp">none</span></samp>&rsquo; (same as &lsquo;<samp><span class="samp">no</span></samp>&rsquo;).
+Individual checks can be enabled with these flags &lsquo;<samp><span class="samp">assert</span></samp>&rsquo;,
+&lsquo;<samp><span class="samp">df</span></samp>&rsquo;, &lsquo;<samp><span class="samp">fold</span></samp>&rsquo;, &lsquo;<samp><span class="samp">gc</span></samp>&rsquo;, &lsquo;<samp><span class="samp">gcac</span></samp>&rsquo; &lsquo;<samp><span class="samp">misc</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rtl</span></samp>&rsquo;,
+&lsquo;<samp><span class="samp">rtlflag</span></samp>&rsquo;, &lsquo;<samp><span class="samp">runtime</span></samp>&rsquo;, &lsquo;<samp><span class="samp">tree</span></samp>&rsquo;, and &lsquo;<samp><span class="samp">valgrind</span></samp>&rsquo;.
+
+ <p>The &lsquo;<samp><span class="samp">valgrind</span></samp>&rsquo; check requires the external <samp><span class="command">valgrind</span></samp>
+simulator, available from <a href="http://valgrind.org/">http://valgrind.org/</a>. The
+&lsquo;<samp><span class="samp">df</span></samp>&rsquo;, &lsquo;<samp><span class="samp">rtl</span></samp>&rsquo;, &lsquo;<samp><span class="samp">gcac</span></samp>&rsquo; and &lsquo;<samp><span class="samp">valgrind</span></samp>&rsquo; checks are very expensive.
+To disable all checking, &lsquo;<samp><span class="samp">--disable-checking</span></samp>&rsquo; or
+&lsquo;<samp><span class="samp">--enable-checking=none</span></samp>&rsquo; must be explicitly requested. Disabling
+assertions will make the compiler and runtime slightly faster but
+increase the risk of undetected internal errors causing wrong code to be
+generated.
+
+ <br><dt><code>--enable-coverage</code><dt><code>--enable-coverage=</code><var>level</var><dd>With this option, the compiler is built to collect self coverage
+information, every time it is run. This is for internal development
+purposes, and only works when the compiler is being built with gcc. The
+<var>level</var> argument controls whether the compiler is built optimized or
+not, values are &lsquo;<samp><span class="samp">opt</span></samp>&rsquo; and &lsquo;<samp><span class="samp">noopt</span></samp>&rsquo;. For coverage analysis you
+want to disable optimization, for performance analysis you want to
+enable optimization. When coverage is enabled, the default level is
+without optimization.
+
+ <br><dt><code>--enable-gather-detailed-mem-stats</code><dd>When this option is specified more detailed information on memory
+allocation is gathered. This information is printed when using
+<samp><span class="option">-fmem-report</span></samp>.
+
+ <br><dt><code>--with-gc</code><dt><code>--with-gc=</code><var>choice</var><dd>With this option you can specify the garbage collector implementation
+used during the compilation process. <var>choice</var> can be one of
+&lsquo;<samp><span class="samp">page</span></samp>&rsquo; and &lsquo;<samp><span class="samp">zone</span></samp>&rsquo;, where &lsquo;<samp><span class="samp">page</span></samp>&rsquo; is the default.
+
+ <br><dt><code>--enable-nls</code><dt><code>--disable-nls</code><dd>The <samp><span class="option">--enable-nls</span></samp> option enables Native Language Support (NLS),
+which lets GCC output diagnostics in languages other than American
+English. Native Language Support is enabled by default if not doing a
+canadian cross build. The <samp><span class="option">--disable-nls</span></samp> option disables NLS.
+
+ <br><dt><code>--with-included-gettext</code><dd>If NLS is enabled, the <samp><span class="option">--with-included-gettext</span></samp> option causes the build
+procedure to prefer its copy of GNU <samp><span class="command">gettext</span></samp>.
+
+ <br><dt><code>--with-catgets</code><dd>If NLS is enabled, and if the host lacks <code>gettext</code> but has the
+inferior <code>catgets</code> interface, the GCC build procedure normally
+ignores <code>catgets</code> and instead uses GCC's copy of the GNU
+<code>gettext</code> library. The <samp><span class="option">--with-catgets</span></samp> option causes the
+build procedure to use the host's <code>catgets</code> in this situation.
+
+ <br><dt><code>--with-libiconv-prefix=</code><var>dir</var><dd>Search for libiconv header files in <samp><var>dir</var><span class="file">/include</span></samp> and
+libiconv library files in <samp><var>dir</var><span class="file">/lib</span></samp>.
+
+ <br><dt><code>--enable-obsolete</code><dd>Enable configuration for an obsoleted system. If you attempt to
+configure GCC for a system (build, host, or target) which has been
+obsoleted, and you do not specify this flag, configure will halt with an
+error message.
+
+ <p>All support for systems which have been obsoleted in one release of GCC
+is removed entirely in the next major release, unless someone steps
+forward to maintain the port.
+
+ <br><dt><code>--enable-decimal-float</code><dt><code>--enable-decimal-float=yes</code><dt><code>--enable-decimal-float=no</code><dt><code>--enable-decimal-float=bid</code><dt><code>--enable-decimal-float=dpd</code><dt><code>--disable-decimal-float</code><dd>Enable (or disable) support for the C decimal floating point extension
+that is in the IEEE 754R extension to the IEEE754 floating point
+standard. This is enabled by default only on PowerPC, i386, and
+x86_64 GNU/Linux systems. Other systems may also support it, but
+require the user to specifically enable it. You can optionally
+control which decimal floating point format is used (either &lsquo;<samp><span class="samp">bid</span></samp>&rsquo;
+or &lsquo;<samp><span class="samp">dpd</span></samp>&rsquo;). The &lsquo;<samp><span class="samp">bid</span></samp>&rsquo; (binary integer decimal) format is
+default on i386 and x86_64 systems, and the &lsquo;<samp><span class="samp">dpd</span></samp>&rsquo; (densely packed
+decimal) format is default on PowerPC systems.
+
+ <br><dt><code>--enable-fixed-point</code><dt><code>--disable-fixed-point</code><dd>Enable (or disable) support for C fixed-point arithmetic.
+This option is enabled by default for some targets (such as MIPS) which
+have hardware-support for fixed-point operations. On other targets, you
+may enable this option manually.
+
+ <br><dt><code>--with-long-double-128</code><dd>Specify if <code>long double</code> type should be 128-bit by default on selected
+GNU/Linux architectures. If using <code>--without-long-double-128</code>,
+<code>long double</code> will be by default 64-bit, the same as <code>double</code> type.
+When neither of these configure options are used, the default will be
+128-bit <code>long double</code> when built against GNU C Library 2.4 and later,
+64-bit <code>long double</code> otherwise.
+
+ <br><dt><code>--with-gmp=</code><var>pathname</var><dt><code>--with-gmp-include=</code><var>pathname</var><dt><code>--with-gmp-lib=</code><var>pathname</var><dt><code>--with-mpfr=</code><var>pathname</var><dt><code>--with-mpfr-include=</code><var>pathname</var><dt><code>--with-mpfr-lib=</code><var>pathname</var><dd>If you do not have GMP (the GNU Multiple Precision library) and the
+MPFR Libraries installed in a standard location and you want to build
+GCC, you can explicitly specify the directory where they are installed
+(&lsquo;<samp><span class="samp">--with-gmp=</span><var>gmpinstalldir</var></samp>&rsquo;,
+&lsquo;<samp><span class="samp">--with-mpfr=</span><var>mpfrinstalldir</var></samp>&rsquo;). The
+<samp><span class="option">--with-gmp=</span><var>gmpinstalldir</var></samp> option is shorthand for
+<samp><span class="option">--with-gmp-lib=</span><var>gmpinstalldir</var><span class="option">/lib</span></samp> and
+<samp><span class="option">--with-gmp-include=</span><var>gmpinstalldir</var><span class="option">/include</span></samp>. Likewise the
+<samp><span class="option">--with-mpfr=</span><var>mpfrinstalldir</var></samp> option is shorthand for
+<samp><span class="option">--with-mpfr-lib=</span><var>mpfrinstalldir</var><span class="option">/lib</span></samp> and
+<samp><span class="option">--with-mpfr-include=</span><var>mpfrinstalldir</var><span class="option">/include</span></samp>. If these
+shorthand assumptions are not correct, you can use the explicit
+include and lib options directly.
+
+ <br><dt><code>--with-debug-prefix-map=</code><var>map</var><dd>Convert source directory names using <samp><span class="option">-fdebug-prefix-map</span></samp> when
+building runtime libraries. &lsquo;<samp><var>map</var></samp>&rsquo; is a space-separated
+list of maps of the form &lsquo;<samp><var>old</var><span class="samp">=</span><var>new</var></samp>&rsquo;.
+
+ </dl>
+
+<h4 class="subheading"><a name="TOC3"></a>Cross-Compiler-Specific Options</h4>
+
+<p>The following options only apply to building cross compilers.
+ <dl>
+<dt><code>--with-sysroot</code><dt><code>--with-sysroot=</code><var>dir</var><dd>Tells GCC to consider <var>dir</var> as the root of a tree that contains a
+(subset of) the root filesystem of the target operating system.
+Target system headers, libraries and run-time object files will be
+searched in there. The specified directory is not copied into the
+install tree, unlike the options <samp><span class="option">--with-headers</span></samp> and
+<samp><span class="option">--with-libs</span></samp> that this option obsoletes. The default value,
+in case <samp><span class="option">--with-sysroot</span></samp> is not given an argument, is
+<samp><span class="option">${gcc_tooldir}/sys-root</span></samp>. If the specified directory is a
+subdirectory of <samp><span class="option">${exec_prefix}</span></samp>, then it will be found relative to
+the GCC binaries if the installation tree is moved.
+
+ <br><dt><code>--with-build-sysroot</code><dt><code>--with-build-sysroot=</code><var>dir</var><dd>Tells GCC to consider <var>dir</var> as the system root (see
+<samp><span class="option">--with-sysroot</span></samp>) while building target libraries, instead of
+the directory specified with <samp><span class="option">--with-sysroot</span></samp>. This option is
+only useful when you are already using <samp><span class="option">--with-sysroot</span></samp>. You
+can use <samp><span class="option">--with-build-sysroot</span></samp> when you are configuring with
+<samp><span class="option">--prefix</span></samp> set to a directory that is different from the one in
+which you are installing GCC and your target libraries.
+
+ <p>This option affects the system root for the compiler used to build
+target libraries (which runs on the build system); it does not affect
+the compiler which is used to build GCC itself.
+
+ <br><dt><code>--with-headers</code><dt><code>--with-headers=</code><var>dir</var><dd>Deprecated in favor of <samp><span class="option">--with-sysroot</span></samp>.
+Specifies that target headers are available when building a cross compiler.
+The <var>dir</var> argument specifies a directory which has the target include
+files. These include files will be copied into the <samp><span class="file">gcc</span></samp> install
+directory. <em>This option with the </em><var>dir</var><em> argument is required</em> when
+building a cross compiler, if <samp><var>prefix</var><span class="file">/</span><var>target</var><span class="file">/sys-include</span></samp>
+doesn't pre-exist. If <samp><var>prefix</var><span class="file">/</span><var>target</var><span class="file">/sys-include</span></samp> does
+pre-exist, the <var>dir</var> argument may be omitted. <samp><span class="command">fixincludes</span></samp>
+will be run on these files to make them compatible with GCC.
+
+ <br><dt><code>--without-headers</code><dd>Tells GCC not use any target headers from a libc when building a cross
+compiler. When crossing to GNU/Linux, you need the headers so GCC
+can build the exception handling for libgcc.
+
+ <br><dt><code>--with-libs</code><dt><code>--with-libs=``</code><var>dir1</var> <var>dir2</var><code> ... </code><var>dirN</var><code>''</code><dd>Deprecated in favor of <samp><span class="option">--with-sysroot</span></samp>.
+Specifies a list of directories which contain the target runtime
+libraries. These libraries will be copied into the <samp><span class="file">gcc</span></samp> install
+directory. If the directory list is omitted, this option has no
+effect.
+
+ <br><dt><code>--with-newlib</code><dd>Specifies that &lsquo;<samp><span class="samp">newlib</span></samp>&rsquo; is
+being used as the target C library. This causes <code>__eprintf</code> to be
+omitted from <samp><span class="file">libgcc.a</span></samp> on the assumption that it will be provided by
+&lsquo;<samp><span class="samp">newlib</span></samp>&rsquo;.
+
+ <br><dt><code>--with-build-time-tools=</code><var>dir</var><dd>Specifies where to find the set of target tools (assembler, linker, etc.)
+that will be used while building GCC itself. This option can be useful
+if the directory layouts are different between the system you are building
+GCC on, and the system where you will deploy it.
+
+ <p>For example, on a <samp><span class="option">ia64-hp-hpux</span></samp> system, you may have the GNU
+assembler and linker in <samp><span class="file">/usr/bin</span></samp>, and the native tools in a
+different path, and build a toolchain that expects to find the
+native tools in <samp><span class="file">/usr/bin</span></samp>.
+
+ <p>When you use this option, you should ensure that <var>dir</var> includes
+<samp><span class="command">ar</span></samp>, <samp><span class="command">as</span></samp>, <samp><span class="command">ld</span></samp>, <samp><span class="command">nm</span></samp>,
+<samp><span class="command">ranlib</span></samp> and <samp><span class="command">strip</span></samp> if necessary, and possibly
+<samp><span class="command">objdump</span></samp>. Otherwise, GCC may use an inconsistent set of
+tools.
+</dl>
+
+<h4 class="subheading"><a name="TOC4"></a>Java-Specific Options</h4>
+
+<p>The following option applies to the build of the Java front end.
+
+ <dl>
+<dt><code>--disable-libgcj</code><dd>Specify that the run-time libraries
+used by GCJ should not be built. This is useful in case you intend
+to use GCJ with some other run-time, or you're going to install it
+separately, or it just happens not to build on your particular
+machine. In general, if the Java front end is enabled, the GCJ
+libraries will be enabled too, unless they're known to not work on
+the target platform. If GCJ is enabled but &lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo; isn't built, you
+may need to port it; in this case, before modifying the top-level
+<samp><span class="file">configure.in</span></samp> so that &lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo; is enabled by default on this platform,
+you may use <samp><span class="option">--enable-libgcj</span></samp> to override the default.
+
+ </dl>
+
+ <p>The following options apply to building &lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo;.
+
+<h5 class="subsubheading"><a name="TOC5"></a>General Options</h5>
+
+ <dl>
+<dt><code>--enable-java-maintainer-mode</code><dd>By default the &lsquo;<samp><span class="samp">libjava</span></samp>&rsquo; build will not attempt to compile the
+<samp><span class="file">.java</span></samp> source files to <samp><span class="file">.class</span></samp>. Instead, it will use the
+<samp><span class="file">.class</span></samp> files from the source tree. If you use this option you
+must have executables named <samp><span class="command">ecj1</span></samp> and <samp><span class="command">gjavah</span></samp> in your path
+for use by the build. You must use this option if you intend to
+modify any <samp><span class="file">.java</span></samp> files in <samp><span class="file">libjava</span></samp>.
+
+ <br><dt><code>--with-java-home=</code><var>dirname</var><dd>This &lsquo;<samp><span class="samp">libjava</span></samp>&rsquo; option overrides the default value of the
+&lsquo;<samp><span class="samp">java.home</span></samp>&rsquo; system property. It is also used to set
+&lsquo;<samp><span class="samp">sun.boot.class.path</span></samp>&rsquo; to <samp><var>dirname</var><span class="file">/lib/rt.jar</span></samp>. By
+default &lsquo;<samp><span class="samp">java.home</span></samp>&rsquo; is set to <samp><var>prefix</var></samp> and
+&lsquo;<samp><span class="samp">sun.boot.class.path</span></samp>&rsquo; to
+<samp><var>datadir</var><span class="file">/java/libgcj-</span><var>version</var><span class="file">.jar</span></samp>.
+
+ <br><dt><code>--with-ecj-jar=</code><var>filename</var><dd>This option can be used to specify the location of an external jar
+file containing the Eclipse Java compiler. A specially modified
+version of this compiler is used by <samp><span class="command">gcj</span></samp> to parse
+<samp><span class="file">.java</span></samp> source files. If this option is given, the
+&lsquo;<samp><span class="samp">libjava</span></samp>&rsquo; build will create and install an <samp><span class="file">ecj1</span></samp> executable
+which uses this jar file at runtime.
+
+ <p>If this option is not given, but an <samp><span class="file">ecj.jar</span></samp> file is found in
+the topmost source tree at configure time, then the &lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo;
+build will create and install <samp><span class="file">ecj1</span></samp>, and will also install the
+discovered <samp><span class="file">ecj.jar</span></samp> into a suitable place in the install tree.
+
+ <p>If <samp><span class="file">ecj1</span></samp> is not installed, then the user will have to supply one
+on his path in order for <samp><span class="command">gcj</span></samp> to properly parse <samp><span class="file">.java</span></samp>
+source files. A suitable jar is available from
+<a href="ftp://sourceware.org/pub/java/">ftp://sourceware.org/pub/java/</a>.
+
+ <br><dt><code>--disable-getenv-properties</code><dd>Don't set system properties from <samp><span class="env">GCJ_PROPERTIES</span></samp>.
+
+ <br><dt><code>--enable-hash-synchronization</code><dd>Use a global hash table for monitor locks. Ordinarily,
+&lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo;'s &lsquo;<samp><span class="samp">configure</span></samp>&rsquo; script automatically makes
+the correct choice for this option for your platform. Only use
+this if you know you need the library to be configured differently.
+
+ <br><dt><code>--enable-interpreter</code><dd>Enable the Java interpreter. The interpreter is automatically
+enabled by default on all platforms that support it. This option
+is really only useful if you want to disable the interpreter
+(using <samp><span class="option">--disable-interpreter</span></samp>).
+
+ <br><dt><code>--disable-java-net</code><dd>Disable java.net. This disables the native part of java.net only,
+using non-functional stubs for native method implementations.
+
+ <br><dt><code>--disable-jvmpi</code><dd>Disable JVMPI support.
+
+ <br><dt><code>--disable-libgcj-bc</code><dd>Disable BC ABI compilation of certain parts of libgcj. By default,
+some portions of libgcj are compiled with <samp><span class="option">-findirect-dispatch</span></samp>
+and <samp><span class="option">-fno-indirect-classes</span></samp>, allowing them to be overridden at
+run-time.
+
+ <p>If <samp><span class="option">--disable-libgcj-bc</span></samp> is specified, libgcj is built without
+these options. This allows the compile-time linker to resolve
+dependencies when statically linking to libgcj. However it makes it
+impossible to override the affected portions of libgcj at run-time.
+
+ <br><dt><code>--with-ecos</code><dd>Enable runtime eCos target support.
+
+ <br><dt><code>--without-libffi</code><dd>Don't use &lsquo;<samp><span class="samp">libffi</span></samp>&rsquo;. This will disable the interpreter and JNI
+support as well, as these require &lsquo;<samp><span class="samp">libffi</span></samp>&rsquo; to work.
+
+ <br><dt><code>--enable-libgcj-debug</code><dd>Enable runtime debugging code.
+
+ <br><dt><code>--enable-libgcj-multifile</code><dd>If specified, causes all <samp><span class="file">.java</span></samp> source files to be
+compiled into <samp><span class="file">.class</span></samp> files in one invocation of
+&lsquo;<samp><span class="samp">gcj</span></samp>&rsquo;. This can speed up build time, but is more
+resource-intensive. If this option is unspecified or
+disabled, &lsquo;<samp><span class="samp">gcj</span></samp>&rsquo; is invoked once for each <samp><span class="file">.java</span></samp>
+file to compile into a <samp><span class="file">.class</span></samp> file.
+
+ <br><dt><code>--with-libiconv-prefix=DIR</code><dd>Search for libiconv in <samp><span class="file">DIR/include</span></samp> and <samp><span class="file">DIR/lib</span></samp>.
+
+ <br><dt><code>--enable-sjlj-exceptions</code><dd>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions.
+&lsquo;<samp><span class="samp">configure</span></samp>&rsquo; ordinarily picks the correct value based on the platform.
+Only use this option if you are sure you need a different setting.
+
+ <br><dt><code>--with-system-zlib</code><dd>Use installed &lsquo;<samp><span class="samp">zlib</span></samp>&rsquo; rather than that included with GCC.
+
+ <br><dt><code>--with-win32-nlsapi=ansi, unicows or unicode</code><dd>Indicates how MinGW &lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo; translates between UNICODE
+characters and the Win32 API.
+ <dl>
+<dt><code>ansi</code><dd>Use the single-byte <code>char</code> and the Win32 A functions natively,
+translating to and from UNICODE when using these functions. If
+unspecified, this is the default.
+
+ <br><dt><code>unicows</code><dd>Use the <code>WCHAR</code> and Win32 W functions natively. Adds
+<code>-lunicows</code> to <samp><span class="file">libgcj.spec</span></samp> to link with &lsquo;<samp><span class="samp">libunicows</span></samp>&rsquo;.
+<samp><span class="file">unicows.dll</span></samp> needs to be deployed on Microsoft Windows 9X machines
+running built executables. <samp><span class="file">libunicows.a</span></samp>, an open-source
+import library around Microsoft's <code>unicows.dll</code>, is obtained from
+<a href="http://libunicows.sourceforge.net/">http://libunicows.sourceforge.net/</a>, which also gives details
+on getting <samp><span class="file">unicows.dll</span></samp> from Microsoft.
+
+ <br><dt><code>unicode</code><dd>Use the <code>WCHAR</code> and Win32 W functions natively. Does <em>not</em>
+add <code>-lunicows</code> to <samp><span class="file">libgcj.spec</span></samp>. The built executables will
+only run on Microsoft Windows NT and above.
+</dl>
+ </dl>
+
+<h5 class="subsubheading"><a name="TOC6"></a>AWT-Specific Options</h5>
+
+ <dl>
+<dt><code>--with-x</code><dd>Use the X Window System.
+
+ <br><dt><code>--enable-java-awt=PEER(S)</code><dd>Specifies the AWT peer library or libraries to build alongside
+&lsquo;<samp><span class="samp">libgcj</span></samp>&rsquo;. If this option is unspecified or disabled, AWT
+will be non-functional. Current valid values are <samp><span class="option">gtk</span></samp> and
+<samp><span class="option">xlib</span></samp>. Multiple libraries should be separated by a
+comma (i.e. <samp><span class="option">--enable-java-awt=gtk,xlib</span></samp>).
+
+ <br><dt><code>--enable-gtk-cairo</code><dd>Build the cairo Graphics2D implementation on GTK.
+
+ <br><dt><code>--enable-java-gc=TYPE</code><dd>Choose garbage collector. Defaults to <samp><span class="option">boehm</span></samp> if unspecified.
+
+ <br><dt><code>--disable-gtktest</code><dd>Do not try to compile and run a test GTK+ program.
+
+ <br><dt><code>--disable-glibtest</code><dd>Do not try to compile and run a test GLIB program.
+
+ <br><dt><code>--with-libart-prefix=PFX</code><dd>Prefix where libart is installed (optional).
+
+ <br><dt><code>--with-libart-exec-prefix=PFX</code><dd>Exec prefix where libart is installed (optional).
+
+ <br><dt><code>--disable-libarttest</code><dd>Do not try to compile and run a test libart program.
+
+</dl>
+
+ <p><hr />
+<p><a href="./index.html">Return to the GCC Installation page</a>
+
+<!-- ***Building**************************************************************** -->
+<!-- ***Testing***************************************************************** -->
+<!-- ***Final install*********************************************************** -->
+<!-- ***Binaries**************************************************************** -->
+<!-- ***Specific**************************************************************** -->
+<!-- ***Old documentation****************************************************** -->
+<!-- ***GFDL******************************************************************** -->
+<!-- *************************************************************************** -->
+<!-- Part 6 The End of the Document -->
+</body></html>
+