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1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with no 8Invariant Sections, the Front-Cover texts being (a) (see below), and 9with the Back-Cover Texts being (b) (see below). A copy of the 10license is included in the section entitled "GNU 11Free Documentation License". 12 13(a) The FSF's Front-Cover Text is: 14 15A GNU Manual 16 17(b) The FSF's Back-Cover Text is: 18 19You have freedom to copy and modify this GNU Manual, like GNU 20 software. Copies published by the Free Software Foundation raise 21 funds for GNU development. --> 22<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> 23<head> 24<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 25<title>Installing GCC</title> 26 27<meta name="description" content="Installing GCC"> 28<meta name="keywords" content="Installing GCC"> 29<meta name="resource-type" content="document"> 30<meta name="distribution" content="global"> 31<meta name="Generator" content="makeinfo"> 32<style type="text/css"> 33<!-- 34a.summary-letter {text-decoration: none} 35blockquote.indentedblock {margin-right: 0em} 36blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 37blockquote.smallquotation {font-size: smaller} 38div.display {margin-left: 3.2em} 39div.example {margin-left: 3.2em} 40div.lisp {margin-left: 3.2em} 41div.smalldisplay {margin-left: 3.2em} 42div.smallexample {margin-left: 3.2em} 43div.smalllisp {margin-left: 3.2em} 44kbd {font-style: oblique} 45pre.display {font-family: inherit} 46pre.format {font-family: inherit} 47pre.menu-comment {font-family: serif} 48pre.menu-preformatted {font-family: serif} 49pre.smalldisplay {font-family: inherit; font-size: smaller} 50pre.smallexample {font-size: smaller} 51pre.smallformat {font-family: inherit; font-size: smaller} 52pre.smalllisp {font-size: smaller} 53span.nolinebreak {white-space: nowrap} 54span.roman {font-family: initial; font-weight: normal} 55span.sansserif {font-family: sans-serif; font-weight: normal} 56ul.no-bullet {list-style: none} 57--> 58</style> 59 60 61</head> 62 63<body lang="en"> 64<h1 class="settitle" align="center">Installing GCC</h1> 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84<a name="index-Configuration"></a> 85<a name="index-Installing-GCC_003a-Configuration"></a> 86 87<p>Like most GNU software, GCC must be configured before it can be built. 88This document describes the recommended configuration procedure 89for both native and cross targets. 90</p> 91<p>We use <var>srcdir</var> to refer to the toplevel source directory for 92GCC; we use <var>objdir</var> to refer to the toplevel build/object directory. 93</p> 94<p>If you obtained the sources by cloning the repository, <var>srcdir</var> 95must refer to the top <samp>gcc</samp> directory, the one where the 96<samp>MAINTAINERS</samp> file can be found, and not its <samp>gcc</samp> 97subdirectory, otherwise the build will fail. 98</p> 99<p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS 100file system, the shell’s built-in <code>pwd</code> command will return 101temporary pathnames. Using these can lead to various sorts of build 102problems. To avoid this issue, set the <code>PWDCMD</code> environment 103variable to an automounter-aware <code>pwd</code> command, e.g., 104<code>pawd</code> or ‘<samp>amq -w</samp>’, during the configuration and build 105phases. 106</p> 107<p>First, we <strong>highly</strong> recommend that GCC be built into a 108separate directory from the sources which does <strong>not</strong> reside 109within the source tree. This is how we generally build GCC; building 110where <var>srcdir</var> == <var>objdir</var> should still work, but doesn’t 111get extensive testing; building where <var>objdir</var> is a subdirectory 112of <var>srcdir</var> is unsupported. 113</p> 114<p>If you have previously built GCC in the same directory for a 115different target machine, do ‘<samp>make distclean</samp>’ to delete all files 116that might be invalid. One of the files this deletes is <samp>Makefile</samp>; 117if ‘<samp>make distclean</samp>’ complains that <samp>Makefile</samp> does not exist 118or issues a message like “don’t know how to make distclean” it probably 119means that the directory is already suitably clean. However, with the 120recommended method of building in a separate <var>objdir</var>, you should 121simply use a different <var>objdir</var> for each target. 122</p> 123<p>Second, when configuring a native system, either <code>cc</code> or 124<code>gcc</code> must be in your path or you must set <code>CC</code> in 125your environment before running configure. Otherwise the configuration 126scripts may fail. 127</p> 128 129<p>To configure GCC: 130</p> 131<div class="smallexample"> 132<pre class="smallexample">% mkdir <var>objdir</var> 133% cd <var>objdir</var> 134% <var>srcdir</var>/configure [<var>options</var>] [<var>target</var>] 135</pre></div> 136 137<a name="Distributor-options"></a> 138<h3 class="heading">Distributor options</h3> 139 140<p>If you will be distributing binary versions of GCC, with modifications 141to the source code, you should use the options described in this 142section to make clear that your version contains modifications. 143</p> 144<dl compact="compact"> 145<dt><code>--with-pkgversion=<var>version</var></code></dt> 146<dd><p>Specify a string that identifies your package. You may wish 147to include a build number or build date. This version string will be 148included in the output of <code>gcc --version</code>. This suffix does 149not replace the default version string, only the ‘<samp>GCC</samp>’ part. 150</p> 151<p>The default value is ‘<samp>GCC</samp>’. 152</p> 153</dd> 154<dt><code>--with-bugurl=<var>url</var></code></dt> 155<dd><p>Specify the URL that users should visit if they wish to report a bug. 156You are of course welcome to forward bugs reported to you to the FSF, 157if you determine that they are not bugs in your modifications. 158</p> 159<p>The default value refers to the FSF’s GCC bug tracker. 160</p> 161</dd> 162</dl> 163 164<a name="Target-specification"></a> 165<h3 class="heading">Target specification</h3> 166<ul> 167<li> GCC has code to correctly determine the correct value for <var>target</var> 168for nearly all native systems. Therefore, we highly recommend you do 169not provide a configure target when configuring a native compiler. 170 171</li><li> <var>target</var> must be specified as <samp>--target=<var>target</var></samp> 172when configuring a cross compiler; examples of valid targets would be 173m68k-elf, sh-elf, etc. 174 175</li><li> Specifying just <var>target</var> instead of <samp>--target=<var>target</var></samp> 176implies that the host defaults to <var>target</var>. 177</li></ul> 178 179 180<a name="Options-specification"></a> 181<h3 class="heading">Options specification</h3> 182 183<p>Use <var>options</var> to override several configure time options for 184GCC. A list of supported <var>options</var> follows; ‘<samp>configure 185--help</samp>’ may list other options, but those not listed below may not 186work and should not normally be used. 187</p> 188<p>Note that each <samp>--enable</samp> option has a corresponding 189<samp>--disable</samp> option and that each <samp>--with</samp> option has a 190corresponding <samp>--without</samp> option. 191</p> 192<dl compact="compact"> 193<dt><code>--prefix=<var>dirname</var></code></dt> 194<dd><p>Specify the toplevel installation 195directory. This is the recommended way to install the tools into a directory 196other than the default. The toplevel installation directory defaults to 197<samp>/usr/local</samp>. 198</p> 199<p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a 200subdirectory of <var>objdir</var> or vice versa. If specifying a directory 201beneath a user’s home directory tree, some shells will not expand 202<var>dirname</var> correctly if it contains the ‘<samp>~</samp>’ metacharacter; use 203<code>$HOME</code> instead. 204</p> 205<p>The following standard <code>autoconf</code> options are supported. Normally you 206should not need to use these options. 207</p><dl compact="compact"> 208<dt><code>--exec-prefix=<var>dirname</var></code></dt> 209<dd><p>Specify the toplevel installation directory for architecture-dependent 210files. The default is <samp><var>prefix</var></samp>. 211</p> 212</dd> 213<dt><code>--bindir=<var>dirname</var></code></dt> 214<dd><p>Specify the installation directory for the executables called by users 215(such as <code>gcc</code> and <code>g++</code>). The default is 216<samp><var>exec-prefix</var>/bin</samp>. 217</p> 218</dd> 219<dt><code>--libdir=<var>dirname</var></code></dt> 220<dd><p>Specify the installation directory for object code libraries and 221internal data files of GCC. The default is <samp><var>exec-prefix</var>/lib</samp>. 222</p> 223</dd> 224<dt><code>--libexecdir=<var>dirname</var></code></dt> 225<dd><p>Specify the installation directory for internal executables of GCC. 226The default is <samp><var>exec-prefix</var>/libexec</samp>. 227</p> 228</dd> 229<dt><code>--with-slibdir=<var>dirname</var></code></dt> 230<dd><p>Specify the installation directory for the shared libgcc library. The 231default is <samp><var>libdir</var></samp>. 232</p> 233</dd> 234<dt><code>--datarootdir=<var>dirname</var></code></dt> 235<dd><p>Specify the root of the directory tree for read-only architecture-independent 236data files referenced by GCC. The default is <samp><var>prefix</var>/share</samp>. 237</p> 238</dd> 239<dt><code>--infodir=<var>dirname</var></code></dt> 240<dd><p>Specify the installation directory for documentation in info format. 241The default is <samp><var>datarootdir</var>/info</samp>. 242</p> 243</dd> 244<dt><code>--datadir=<var>dirname</var></code></dt> 245<dd><p>Specify the installation directory for some architecture-independent 246data files referenced by GCC. The default is <samp><var>datarootdir</var></samp>. 247</p> 248</dd> 249<dt><code>--docdir=<var>dirname</var></code></dt> 250<dd><p>Specify the installation directory for documentation files (other 251than Info) for GCC. The default is <samp><var>datarootdir</var>/doc</samp>. 252</p> 253</dd> 254<dt><code>--htmldir=<var>dirname</var></code></dt> 255<dd><p>Specify the installation directory for HTML documentation files. 256The default is <samp><var>docdir</var></samp>. 257</p> 258</dd> 259<dt><code>--pdfdir=<var>dirname</var></code></dt> 260<dd><p>Specify the installation directory for PDF documentation files. 261The default is <samp><var>docdir</var></samp>. 262</p> 263</dd> 264<dt><code>--mandir=<var>dirname</var></code></dt> 265<dd><p>Specify the installation directory for manual pages. The default is 266<samp><var>datarootdir</var>/man</samp>. (Note that the manual pages are only extracts 267from the full GCC manuals, which are provided in Texinfo format. The manpages 268are derived by an automatic conversion process from parts of the full 269manual.) 270</p> 271</dd> 272<dt><code>--with-gxx-include-dir=<var>dirname</var></code></dt> 273<dd><p>Specify 274the installation directory for G++ header files. The default depends 275on other configuration options, and differs between cross and native 276configurations. 277</p> 278</dd> 279<dt><code>--with-specs=<var>specs</var></code></dt> 280<dd><p>Specify additional command line driver SPECS. 281This can be useful if you need to turn on a non-standard feature by 282default without modifying the compiler’s source code, for instance 283<samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>. 284See “Spec Files” in the main manual 285</p> 286</dd> 287</dl> 288 289</dd> 290<dt><code>--program-prefix=<var>prefix</var></code></dt> 291<dd><p>GCC supports some transformations of the names of its programs when 292installing them. This option prepends <var>prefix</var> to the names of 293programs to install in <var>bindir</var> (see above). For example, specifying 294<samp>--program-prefix=foo-</samp> would result in ‘<samp>gcc</samp>’ 295being installed as <samp>/usr/local/bin/foo-gcc</samp>. 296</p> 297</dd> 298<dt><code>--program-suffix=<var>suffix</var></code></dt> 299<dd><p>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var> 300(see above). For example, specifying <samp>--program-suffix=-3.1</samp> 301would result in ‘<samp>gcc</samp>’ being installed as 302<samp>/usr/local/bin/gcc-3.1</samp>. 303</p> 304</dd> 305<dt><code>--program-transform-name=<var>pattern</var></code></dt> 306<dd><p>Applies the ‘<samp>sed</samp>’ script <var>pattern</var> to be applied to the names 307of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to 308consist of one or more basic ‘<samp>sed</samp>’ editing commands, separated by 309semicolons. For example, if you want the ‘<samp>gcc</samp>’ program name to be 310transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and 311the ‘<samp>g++</samp>’ program name to be transformed to 312<samp>/usr/local/bin/gspecial++</samp> without changing other program names, 313you could use the pattern 314<samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp> 315to achieve this effect. 316</p> 317<p>All three options can be combined and used together, resulting in more 318complex conversion patterns. As a basic rule, <var>prefix</var> (and 319<var>suffix</var>) are prepended (appended) before further transformations 320can happen with a special transformation script <var>pattern</var>. 321</p> 322<p>As currently implemented, this option only takes effect for native 323builds; cross compiler binaries’ names are not transformed even when a 324transformation is explicitly asked for by one of these options. 325</p> 326<p>For native builds, some of the installed programs are also installed 327with the target alias in front of their name, as in 328‘<samp>i686-pc-linux-gnu-gcc</samp>’. All of the above transformations happen 329before the target alias is prepended to the name—so, specifying 330<samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the 331resulting binary would be installed as 332<samp>/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>. 333</p> 334<p>As a last shortcoming, none of the installed Ada programs are 335transformed yet, which will be fixed in some time. 336</p> 337</dd> 338<dt><code>--with-local-prefix=<var>dirname</var></code></dt> 339<dd><p>Specify the 340installation directory for local include files. The default is 341<samp>/usr/local</samp>. Specify this option if you want the compiler to 342search directory <samp><var>dirname</var>/include</samp> for locally installed 343header files <em>instead</em> of <samp>/usr/local/include</samp>. 344</p> 345<p>You should specify <samp>--with-local-prefix</samp> <strong>only</strong> if your 346site has a different convention (not <samp>/usr/local</samp>) for where to put 347site-specific files. 348</p> 349<p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp> 350regardless of the value of <samp>--prefix</samp>. Specifying 351<samp>--prefix</samp> has no effect on which directory GCC searches for 352local header files. This may seem counterintuitive, but actually it is 353logical. 354</p> 355<p>The purpose of <samp>--prefix</samp> is to specify where to <em>install 356GCC</em>. The local header files in <samp>/usr/local/include</samp>—if you put 357any in that directory—are not part of GCC. They are part of other 358programs—perhaps many others. (GCC installs its own header files in 359another directory which is based on the <samp>--prefix</samp> value.) 360</p> 361<p>Both the local-prefix include directory and the GCC-prefix include 362directory are part of GCC’s “system include” directories. Although these 363two directories are not fixed, they need to be searched in the proper 364order for the correct processing of the include_next directive. The 365local-prefix include directory is searched before the GCC-prefix 366include directory. Another characteristic of system include directories 367is that pedantic warnings are turned off for headers in these directories. 368</p> 369<p>Some autoconf macros add <samp>-I <var>directory</var></samp> options to the 370compiler command line, to ensure that directories containing installed 371packages’ headers are searched. When <var>directory</var> is one of GCC’s 372system include directories, GCC will ignore the option so that system 373directories continue to be processed in the correct order. This 374may result in a search order different from what was specified but the 375directory will still be searched. 376</p> 377<p>GCC automatically searches for ordinary libraries using 378<code>GCC_EXEC_PREFIX</code>. Thus, when the same installation prefix is 379used for both GCC and packages, GCC will automatically search for 380both headers and libraries. This provides a configuration that is 381easy to use. GCC behaves in a manner similar to that when it is 382installed as a system compiler in <samp>/usr</samp>. 383</p> 384<p>Sites that need to install multiple versions of GCC may not want to 385use the above simple configuration. It is possible to use the 386<samp>--program-prefix</samp>, <samp>--program-suffix</samp> and 387<samp>--program-transform-name</samp> options to install multiple versions 388into a single directory, but it may be simpler to use different prefixes 389and the <samp>--with-local-prefix</samp> option to specify the location of the 390site-specific files for each version. It will then be necessary for 391users to specify explicitly the location of local site libraries 392(e.g., with <code>LIBRARY_PATH</code>). 393</p> 394<p>The same value can be used for both <samp>--with-local-prefix</samp> and 395<samp>--prefix</samp> provided it is not <samp>/usr</samp>. This can be used 396to avoid the default search of <samp>/usr/local/include</samp>. 397</p> 398<p><strong>Do not</strong> specify <samp>/usr</samp> as the <samp>--with-local-prefix</samp>! 399The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong> 400contain any of the system’s standard header files. If it did contain 401them, certain programs would be miscompiled (including GNU Emacs, on 402certain targets), because this would override and nullify the header 403file corrections made by the <code>fixincludes</code> script. 404</p> 405<p>Indications are that people who use this option use it based on mistaken 406ideas of what it is for. People use it as if it specified where to 407install part of GCC. Perhaps they make this assumption because 408installing GCC creates the directory. 409</p> 410</dd> 411<dt><code>--with-gcc-major-version-only</code></dt> 412<dd><p>Specifies that GCC should use only the major number rather than 413<var>major</var>.<var>minor</var>.<var>patchlevel</var> in filesystem paths. 414</p> 415</dd> 416<dt><code>--with-native-system-header-dir=<var>dirname</var></code></dt> 417<dd><p>Specifies that <var>dirname</var> is the directory that contains native system 418header files, rather than <samp>/usr/include</samp>. This option is most useful 419if you are creating a compiler that should be isolated from the system 420as much as possible. It is most commonly used with the 421<samp>--with-sysroot</samp> option and will cause GCC to search 422<var>dirname</var> inside the system root specified by that option. 423</p> 424</dd> 425<dt><code>--enable-shared[=<var>package</var>[,…]]</code></dt> 426<dd><p>Build shared versions of libraries, if shared libraries are supported on 427the target platform. Unlike GCC 2.95.x and earlier, shared libraries 428are enabled by default on all platforms that support shared libraries. 429</p> 430<p>If a list of packages is given as an argument, build shared libraries 431only for the listed packages. For other packages, only static libraries 432will be built. Package names currently recognized in the GCC tree are 433‘<samp>libgcc</samp>’ (also known as ‘<samp>gcc</samp>’), ‘<samp>libstdc++</samp>’ (not 434‘<samp>libstdc++-v3</samp>’), ‘<samp>libffi</samp>’, ‘<samp>zlib</samp>’, ‘<samp>boehm-gc</samp>’, 435‘<samp>ada</samp>’, ‘<samp>libada</samp>’, ‘<samp>libgo</samp>’, ‘<samp>libobjc</samp>’, and ‘<samp>libphobos</samp>’. 436Note ‘<samp>libiberty</samp>’ does not support shared libraries at all. 437</p> 438<p>Use <samp>--disable-shared</samp> to build only static libraries. Note that 439<samp>--disable-shared</samp> does not accept a list of package names as 440argument, only <samp>--enable-shared</samp> does. 441</p> 442<p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em> 443code. 444</p> 445</dd> 446<dt><code>--enable-host-shared</code></dt> 447<dd><p>Specify that the <em>host</em> code should be built into position-independent 448machine code (with -fPIC), allowing it to be used within shared libraries, 449but yielding a slightly slower compiler. 450</p> 451<p>This option is required when building the libgccjit.so library. 452</p> 453<p>Contrast with <samp>--enable-shared</samp>, which affects <em>target</em> 454libraries. 455</p> 456</dd> 457<dt><code><a name="with-gnu-as"></a>--with-gnu-as</code></dt> 458<dd><p>Specify that the compiler should assume that the 459assembler it finds is the GNU assembler. However, this does not modify 460the rules to find an assembler and will result in confusion if the 461assembler found is not actually the GNU assembler. (Confusion may also 462result if the compiler finds the GNU assembler but has not been 463configured with <samp>--with-gnu-as</samp>.) If you have more than one 464assembler installed on your system, you may want to use this option in 465connection with <samp>--with-as=<var>pathname</var></samp> or 466<samp>--with-build-time-tools=<var>pathname</var></samp>. 467</p> 468<p>The following systems are the only ones where it makes a difference 469whether you use the GNU assembler. On any other system, 470<samp>--with-gnu-as</samp> has no effect. 471</p> 472<ul> 473<li> ‘<samp>hppa1.0-<var>any</var>-<var>any</var></samp>’ 474</li><li> ‘<samp>hppa1.1-<var>any</var>-<var>any</var></samp>’ 475</li><li> ‘<samp>sparc-sun-solaris2.<var>any</var></samp>’ 476</li><li> ‘<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>’ 477</li></ul> 478 479</dd> 480<dt><code><a name="with-as"></a>--with-as=<var>pathname</var></code></dt> 481<dd><p>Specify that the compiler should use the assembler pointed to by 482<var>pathname</var>, rather than the one found by the standard rules to find 483an assembler, which are: 484</p><ul> 485<li> Unless GCC is being built with a cross compiler, check the 486<samp><var>libexec</var>/gcc/<var>target</var>/<var>version</var></samp> directory. 487<var>libexec</var> defaults to <samp><var>exec-prefix</var>/libexec</samp>; 488<var>exec-prefix</var> defaults to <var>prefix</var>, which 489defaults to <samp>/usr/local</samp> unless overridden by the 490<samp>--prefix=<var>pathname</var></samp> switch described above. <var>target</var> 491is the target system triple, such as ‘<samp>sparc-sun-solaris2.7</samp>’, and 492<var>version</var> denotes the GCC version, such as 3.0. 493 494</li><li> If the target system is the same that you are building on, check 495operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on 496Sun Solaris 2). 497 498</li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the 499target system triple. 500 501</li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the 502target system triple, if the host and target system triple are 503the same (in other words, we use a host tool if it can be used for 504the target as well). 505</li></ul> 506 507<p>You may want to use <samp>--with-as</samp> if no assembler 508is installed in the directories listed above, or if you have multiple 509assemblers installed and want to choose one that is not found by the 510above rules. 511</p> 512</dd> 513<dt><code><a name="with-gnu-ld"></a>--with-gnu-ld</code></dt> 514<dd><p>Same as <a href="#with-gnu-as"><samp>--with-gnu-as</samp></a> 515but for the linker. 516</p> 517</dd> 518<dt><code>--with-ld=<var>pathname</var></code></dt> 519<dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 520but for the linker. 521</p> 522</dd> 523<dt><code>--with-stabs</code></dt> 524<dd><p>Specify that stabs debugging 525information should be used instead of whatever format the host normally 526uses. Normally GCC uses the same debug format as the host system. 527</p> 528</dd> 529<dt><code>--with-tls=<var>dialect</var></code></dt> 530<dd><p>Specify the default TLS dialect, for systems were there is a choice. 531For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or 532<code>gnu2</code>, which select between the original GNU dialect and the GNU TLS 533descriptor-based dialect. 534</p> 535</dd> 536<dt><code>--enable-multiarch</code></dt> 537<dd><p>Specify whether to enable or disable multiarch support. The default is 538to check for glibc start files in a multiarch location, and enable it 539if the files are found. The auto detection is enabled for native builds, 540and for cross builds configured with <samp>--with-sysroot</samp>, and without 541<samp>--with-native-system-header-dir</samp>. 542More documentation about multiarch can be found at 543<a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>. 544</p> 545</dd> 546<dt><code>--enable-sjlj-exceptions</code></dt> 547<dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions. 548‘<samp>configure</samp>’ ordinarily picks the correct value based on the platform. 549Only use this option if you are sure you need a different setting. 550</p> 551</dd> 552<dt><code>--enable-vtable-verify</code></dt> 553<dd><p>Specify whether to enable or disable the vtable verification feature. 554Enabling this feature causes libstdc++ to be built with its virtual calls 555in verifiable mode. This means that, when linked with libvtv, every 556virtual call in libstdc++ will verify the vtable pointer through which the 557call will be made before actually making the call. If not linked with libvtv, 558the verifier will call stub functions (in libstdc++ itself) and do nothing. 559If vtable verification is disabled, then libstdc++ is not built with its 560virtual calls in verifiable mode at all. However the libvtv library will 561still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv). 562<samp>--disable-vtable-verify</samp> is the default. 563</p> 564</dd> 565<dt><code>--disable-gcov</code></dt> 566<dd><p>Specify that the run-time library used for coverage analysis 567and associated host tools should not be built. 568</p> 569</dd> 570<dt><code>--disable-multilib</code></dt> 571<dd><p>Specify that multiple target 572libraries to support different target variants, calling 573conventions, etc. should not be built. The default is to build a 574predefined set of them. 575</p> 576<p>Some targets provide finer-grained control over which multilibs are built 577(e.g., <samp>--disable-softfloat</samp>): 578</p><dl compact="compact"> 579<dt><code>arm-*-*</code></dt> 580<dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult. 581</p> 582</dd> 583<dt><code>m68*-*-*</code></dt> 584<dd><p>softfloat, m68881, m68000, m68020. 585</p> 586</dd> 587<dt><code>mips*-*-*</code></dt> 588<dd><p>single-float, biendian, softfloat. 589</p> 590</dd> 591<dt><code>powerpc*-*-*, rs6000*-*-*</code></dt> 592<dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, 593sysv, aix. 594</p> 595</dd> 596</dl> 597 598</dd> 599<dt><code>--with-multilib-list=<var>list</var></code></dt> 600<dt><code>--without-multilib-list</code></dt> 601<dd><p>Specify what multilibs to build. <var>list</var> is a comma separated list of 602values, possibly consisting of a single value. Currently only implemented 603for aarch64*-*-*, arm*-*-*, riscv*-*-*, sh*-*-* and x86-64-*-linux*. The 604accepted values and meaning for each target is given below. 605</p> 606<dl compact="compact"> 607<dt><code>aarch64*-*-*</code></dt> 608<dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code> 609to enable ILP32 and LP64 run-time libraries, respectively. If 610<var>list</var> is empty, then there will be no multilibs and only the 611default run-time library will be built. If <var>list</var> is 612<code>default</code> or –with-multilib-list= is not specified, then the 613default set of libraries is selected based on the value of 614<samp>--target</samp>. 615</p> 616</dd> 617<dt><code>arm*-*-*</code></dt> 618<dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and 619<code>rmprofile</code> to build multilibs for A or R and M architecture 620profiles respectively. Note that, due to some limitation of the current 621multilib framework, using the combined <code>aprofile,rmprofile</code> 622multilibs selects in some cases a less optimal multilib than when using 623the multilib profile for the architecture targetted. The special value 624<code>default</code> is also accepted and is equivalent to omitting the 625option, i.e., only the default run-time library will be enabled. 626</p> 627<p><var>list</var> may instead contain <code>@name</code>, to use the multilib 628configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in 629the source tree (it is part of the corresponding sources, after all). 630It is recommended, but not required, that files used for this purpose to 631be named starting with <samp>t-ml-</samp>, to make their intended purpose 632self-evident, in line with GCC conventions. Such files enable custom, 633user-chosen multilib lists to be configured. Whether multiple such 634files can be used together depends on the contents of the supplied 635files. See <samp>gcc/config/arm/t-multilib</samp> and its supplementary 636<samp>gcc/config/arm/t-*profile</samp> files for an example of what such 637Makefile fragments might look like for this version of GCC. The macros 638expected to be defined in these fragments are not stable across GCC 639releases, so make sure they define the <code>MULTILIB</code>-related macros 640expected by the version of GCC you are building. 641See “Target Makefile Fragments” in the internals manual. 642</p> 643<p>The table below gives the combination of ISAs, architectures, FPUs and 644floating-point ABIs for which multilibs are built for each predefined 645profile. The union of these options is considered when specifying both 646<code>aprofile</code> and <code>rmprofile</code>. 647</p> 648<table> 649<tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr> 650<tr><td width="15%">ISAs</td><td width="28%"><code>-marm</code> and <code>-mthumb</code></td><td width="30%"><code>-mthumb</code></td></tr> 651<tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br> 652<code>-march=armv7-a</code><br> 653<code>-march=armv7ve</code><br> 654<code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br> 655<code>-march=armv6s-m</code><br> 656<code>-march=armv7-m</code><br> 657<code>-march=armv7e-m</code><br> 658<code>-march=armv8-m.base</code><br> 659<code>-march=armv8-m.main</code><br> 660<code>-march=armv7</code></td></tr> 661<tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br> 662<code>-mfpu=vfpv3-d16</code><br> 663<code>-mfpu=neon</code><br> 664<code>-mfpu=vfpv4-d16</code><br> 665<code>-mfpu=neon-vfpv4</code><br> 666<code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br> 667<code>-mfpu=vfpv3-d16</code><br> 668<code>-mfpu=fpv4-sp-d16</code><br> 669<code>-mfpu=fpv5-sp-d16</code><br> 670<code>-mfpu=fpv5-d16</code><br></td></tr> 671<tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br> 672<code>-mfloat-abi=softfp</code><br> 673<code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br> 674<code>-mfloat-abi=softfp</code><br> 675<code>-mfloat-abi=hard</code></td></tr> 676</table> 677 678</dd> 679<dt><code>riscv*-*-*</code></dt> 680<dd><p><var>list</var> is a single ABI name. The target architecture must be either 681<code>rv32gc</code> or <code>rv64gc</code>. This will build a single multilib for the 682specified architecture and ABI pair. If <code>--with-multilib-list</code> is not 683given, then a default set of multilibs is selected based on the value of 684<samp>--target</samp>. This is usually a large set of multilibs. 685</p> 686</dd> 687<dt><code>sh*-*-*</code></dt> 688<dd><p><var>list</var> is a comma separated list of CPU names. These must be of the 689form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option 690for that processor). The list should not contain any endian options - 691these are handled by <samp>--with-endian</samp>. 692</p> 693<p>If <var>list</var> is empty, then there will be no multilibs for extra 694processors. The multilib for the secondary endian remains enabled. 695</p> 696<p>As a special case, if an entry in the list starts with a <code>!</code> 697(exclamation point), then it is added to the list of excluded multilibs. 698Entries of this sort should be compatible with ‘<samp>MULTILIB_EXCLUDES</samp>’ 699(once the leading <code>!</code> has been stripped). 700</p> 701<p>If <samp>--with-multilib-list</samp> is not given, then a default set of 702multilibs is selected based on the value of <samp>--target</samp>. This is 703usually the complete set of libraries, but some targets imply a more 704specialized subset. 705</p> 706<p>Example 1: to configure a compiler for SH4A only, but supporting both 707endians, with little endian being the default: 708</p><div class="smallexample"> 709<pre class="smallexample">--with-cpu=sh4a --with-endian=little,big --with-multilib-list= 710</pre></div> 711 712<p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with 713only little endian SH4AL: 714</p><div class="smallexample"> 715<pre class="smallexample">--with-cpu=sh4a --with-endian=little,big \ 716--with-multilib-list=sh4al,!mb/m4al 717</pre></div> 718 719</dd> 720<dt><code>x86-64-*-linux*</code></dt> 721<dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and 722<code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries, 723respectively. If <var>list</var> is empty, then there will be no multilibs 724and only the default run-time library will be enabled. 725</p> 726<p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and 72764-bit run-time libraries will be enabled. 728</p></dd> 729</dl> 730 731</dd> 732<dt><code>--with-endian=<var>endians</var></code></dt> 733<dd><p>Specify what endians to use. 734Currently only implemented for sh*-*-*. 735</p> 736<p><var>endians</var> may be one of the following: 737</p><dl compact="compact"> 738<dt><code>big</code></dt> 739<dd><p>Use big endian exclusively. 740</p></dd> 741<dt><code>little</code></dt> 742<dd><p>Use little endian exclusively. 743</p></dd> 744<dt><code>big,little</code></dt> 745<dd><p>Use big endian by default. Provide a multilib for little endian. 746</p></dd> 747<dt><code>little,big</code></dt> 748<dd><p>Use little endian by default. Provide a multilib for big endian. 749</p></dd> 750</dl> 751 752</dd> 753<dt><code>--enable-threads</code></dt> 754<dd><p>Specify that the target 755supports threads. This affects the Objective-C compiler and runtime 756library, and exception handling for other languages like C++. 757On some systems, this is the default. 758</p> 759<p>In general, the best (and, in many cases, the only known) threading 760model available will be configured for use. Beware that on some 761systems, GCC has not been taught what threading models are generally 762available for the system. In this case, <samp>--enable-threads</samp> is an 763alias for <samp>--enable-threads=single</samp>. 764</p> 765</dd> 766<dt><code>--disable-threads</code></dt> 767<dd><p>Specify that threading support should be disabled for the system. 768This is an alias for <samp>--enable-threads=single</samp>. 769</p> 770</dd> 771<dt><code>--enable-threads=<var>lib</var></code></dt> 772<dd><p>Specify that 773<var>lib</var> is the thread support library. This affects the Objective-C 774compiler and runtime library, and exception handling for other languages 775like C++. The possibilities for <var>lib</var> are: 776</p> 777<dl compact="compact"> 778<dt><code>aix</code></dt> 779<dd><p>AIX thread support. 780</p></dd> 781<dt><code>dce</code></dt> 782<dd><p>DCE thread support. 783</p></dd> 784<dt><code>lynx</code></dt> 785<dd><p>LynxOS thread support. 786</p></dd> 787<dt><code>mipssde</code></dt> 788<dd><p>MIPS SDE thread support. 789</p></dd> 790<dt><code>no</code></dt> 791<dd><p>This is an alias for ‘<samp>single</samp>’. 792</p></dd> 793<dt><code>posix</code></dt> 794<dd><p>Generic POSIX/Unix98 thread support. 795</p></dd> 796<dt><code>rtems</code></dt> 797<dd><p>RTEMS thread support. 798</p></dd> 799<dt><code>single</code></dt> 800<dd><p>Disable thread support, should work for all platforms. 801</p></dd> 802<dt><code>tpf</code></dt> 803<dd><p>TPF thread support. 804</p></dd> 805<dt><code>vxworks</code></dt> 806<dd><p>VxWorks thread support. 807</p></dd> 808<dt><code>win32</code></dt> 809<dd><p>Microsoft Win32 API thread support. 810</p></dd> 811</dl> 812 813</dd> 814<dt><code>--enable-tls</code></dt> 815<dd><p>Specify that the target supports TLS (Thread Local Storage). Usually 816configure can correctly determine if TLS is supported. In cases where 817it guesses incorrectly, TLS can be explicitly enabled or disabled with 818<samp>--enable-tls</samp> or <samp>--disable-tls</samp>. This can happen if 819the assembler supports TLS but the C library does not, or if the 820assumptions made by the configure test are incorrect. 821</p> 822</dd> 823<dt><code>--disable-tls</code></dt> 824<dd><p>Specify that the target does not support TLS. 825This is an alias for <samp>--enable-tls=no</samp>. 826</p> 827</dd> 828<dt><code>--with-cpu=<var>cpu</var></code></dt> 829<dt><code>--with-cpu-32=<var>cpu</var></code></dt> 830<dt><code>--with-cpu-64=<var>cpu</var></code></dt> 831<dd><p>Specify which cpu variant the compiler should generate code for by default. 832<var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch. 833This option is only supported on some targets, including ARC, ARM, i386, M68k, 834PowerPC, and SPARC. It is mandatory for ARC. The <samp>--with-cpu-32</samp> and 835<samp>--with-cpu-64</samp> options specify separate default CPUs for 83632-bit and 64-bit modes; these options are only supported for i386, 837x86-64, PowerPC, and SPARC. 838</p> 839</dd> 840<dt><code>--with-schedule=<var>cpu</var></code></dt> 841<dt><code>--with-arch=<var>cpu</var></code></dt> 842<dt><code>--with-arch-32=<var>cpu</var></code></dt> 843<dt><code>--with-arch-64=<var>cpu</var></code></dt> 844<dt><code>--with-tune=<var>cpu</var></code></dt> 845<dt><code>--with-tune-32=<var>cpu</var></code></dt> 846<dt><code>--with-tune-64=<var>cpu</var></code></dt> 847<dt><code>--with-abi=<var>abi</var></code></dt> 848<dt><code>--with-fpu=<var>type</var></code></dt> 849<dt><code>--with-float=<var>type</var></code></dt> 850<dd><p>These configure options provide default values for the <samp>-mschedule=</samp>, 851<samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp> 852options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>. As with 853<samp>--with-cpu</samp>, which switches will be accepted and acceptable values 854of the arguments depend on the target. 855</p> 856</dd> 857<dt><code>--with-mode=<var>mode</var></code></dt> 858<dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>. 859This option is only supported on ARM targets. 860</p> 861</dd> 862<dt><code>--with-stack-offset=<var>num</var></code></dt> 863<dd><p>This option sets the default for the -mstack-offset=<var>num</var> option, 864and will thus generally also control the setting of this option for 865libraries. This option is only supported on Epiphany targets. 866</p> 867</dd> 868<dt><code>--with-fpmath=<var>isa</var></code></dt> 869<dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default 870ISA for floating-point arithmetics. You can select either ‘<samp>sse</samp>’ which 871enables <samp>-msse2</samp> or ‘<samp>avx</samp>’ which enables <samp>-mavx</samp> by default. 872This option is only supported on i386 and x86-64 targets. 873</p> 874</dd> 875<dt><code>--with-fp-32=<var>mode</var></code></dt> 876<dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using 877the o32 ABI. The possibilities for <var>mode</var> are: 878</p><dl compact="compact"> 879<dt><code>32</code></dt> 880<dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line 881option. 882</p></dd> 883<dt><code>xx</code></dt> 884<dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line 885option. 886</p></dd> 887<dt><code>64</code></dt> 888<dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line 889option. 890</p></dd> 891</dl> 892<p>In the absence of this configuration option the default is to use the o32 893FP32 ABI extension. 894</p> 895</dd> 896<dt><code>--with-odd-spreg-32</code></dt> 897<dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using 898the o32 ABI. 899</p> 900</dd> 901<dt><code>--without-odd-spreg-32</code></dt> 902<dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using 903the o32 ABI. This is normally used in conjunction with 904<samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension. 905</p> 906</dd> 907<dt><code>--with-nan=<var>encoding</var></code></dt> 908<dd><p>On MIPS targets, set the default encoding convention to use for the 909special not-a-number (NaN) IEEE 754 floating-point data. The 910possibilities for <var>encoding</var> are: 911</p><dl compact="compact"> 912<dt><code>legacy</code></dt> 913<dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line 914option. 915</p></dd> 916<dt><code>2008</code></dt> 917<dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line 918option. 919</p></dd> 920</dl> 921<p>To use this configuration option you must have an assembler version 922installed that supports the <samp>-mnan=</samp> command-line option too. 923In the absence of this configuration option the default convention is 924the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and 925<samp>-mnan=legacy</samp> command-line options has been used. 926</p> 927</dd> 928<dt><code>--with-divide=<var>type</var></code></dt> 929<dd><p>Specify how the compiler should generate code for checking for 930division by zero. This option is only supported on the MIPS target. 931The possibilities for <var>type</var> are: 932</p><dl compact="compact"> 933<dt><code>traps</code></dt> 934<dd><p>Division by zero checks use conditional traps (this is the default on 935systems that support conditional traps). 936</p></dd> 937<dt><code>breaks</code></dt> 938<dd><p>Division by zero checks use the break instruction. 939</p></dd> 940</dl> 941 942 943</dd> 944<dt><code>--with-llsc</code></dt> 945<dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no 946<samp>-mno-llsc</samp> option is passed. This is the default for 947Linux-based targets, as the kernel will emulate them if the ISA does 948not provide them. 949</p> 950</dd> 951<dt><code>--without-llsc</code></dt> 952<dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no 953<samp>-mllsc</samp> option is passed. 954</p> 955</dd> 956<dt><code>--with-synci</code></dt> 957<dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no 958<samp>-mno-synci</samp> option is passed. 959</p> 960</dd> 961<dt><code>--without-synci</code></dt> 962<dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no 963<samp>-msynci</samp> option is passed. This is the default. 964</p> 965</dd> 966<dt><code>--with-lxc1-sxc1</code></dt> 967<dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no 968<samp>-mno-lxc1-sxc1</samp> option is passed. This is the default. 969</p> 970</dd> 971<dt><code>--without-lxc1-sxc1</code></dt> 972<dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no 973<samp>-mlxc1-sxc1</samp> option is passed. The indexed load/store 974instructions are not directly a problem but can lead to unexpected 975behaviour when deployed in an application intended for a 32-bit address 976space but run on a 64-bit processor. The issue is seen because all 977known MIPS 64-bit Linux kernels execute o32 and n32 applications 978with 64-bit addressing enabled which affects the overflow behaviour 979of the indexed addressing mode. GCC will assume that ordinary 98032-bit arithmetic overflow behaviour is the same whether performed 981as an <code>addu</code> instruction or as part of the address calculation 982in <code>lwxc1</code> type instructions. This assumption holds true in a 983pure 32-bit environment and can hold true in a 64-bit environment if 984the address space is accurately set to be 32-bit for o32 and n32. 985</p> 986</dd> 987<dt><code>--with-madd4</code></dt> 988<dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no 989<samp>-mno-madd4</samp> option is passed. This is the default. 990</p> 991</dd> 992<dt><code>--without-madd4</code></dt> 993<dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no 994<samp>-mmadd4</samp> option is passed. The <code>madd4</code> instruction 995family can be problematic when targeting a combination of cores that 996implement these instructions differently. There are two known cores 997that implement these as fused operations instead of unfused (where 998unfused is normally expected). Disabling these instructions is the 999only way to ensure compatible code is generated; this will incur 1000a performance penalty. 1001</p> 1002</dd> 1003<dt><code>--with-mips-plt</code></dt> 1004<dd><p>On MIPS targets, make use of copy relocations and PLTs. 1005These features are extensions to the traditional 1006SVR4-based MIPS ABIs and require support from GNU binutils 1007and the runtime C library. 1008</p> 1009</dd> 1010<dt><code>--with-stack-clash-protection-guard-size=<var>size</var></code></dt> 1011<dd><p>On certain targets this option sets the default stack clash protection guard 1012size as a power of two in bytes. On AArch64 <var>size</var> is required to be either 101312 (4KB) or 16 (64KB). 1014</p> 1015</dd> 1016<dt><code>--enable-__cxa_atexit</code></dt> 1017<dd><p>Define if you want to use __cxa_atexit, rather than atexit, to 1018register C++ destructors for local statics and global objects. 1019This is essential for fully standards-compliant handling of 1020destructors, but requires __cxa_atexit in libc. This option is currently 1021only available on systems with GNU libc. When enabled, this will cause 1022<samp>-fuse-cxa-atexit</samp> to be passed by default. 1023</p> 1024</dd> 1025<dt><code>--enable-gnu-indirect-function</code></dt> 1026<dd><p>Define if you want to enable the <code>ifunc</code> attribute. This option is 1027currently only available on systems with GNU libc on certain targets. 1028</p> 1029</dd> 1030<dt><code>--enable-target-optspace</code></dt> 1031<dd><p>Specify that target 1032libraries should be optimized for code space instead of code speed. 1033This is the default for the m32r platform. 1034</p> 1035</dd> 1036<dt><code>--with-cpp-install-dir=<var>dirname</var></code></dt> 1037<dd><p>Specify that the user visible <code>cpp</code> program should be installed 1038in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>. 1039</p> 1040</dd> 1041<dt><code>--enable-comdat</code></dt> 1042<dd><p>Enable COMDAT group support. This is primarily used to override the 1043automatically detected value. 1044</p> 1045</dd> 1046<dt><code>--enable-initfini-array</code></dt> 1047<dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code> 1048(instead of <code>.init</code> and <code>.fini</code>) for constructors and 1049destructors. Option <samp>--disable-initfini-array</samp> has the 1050opposite effect. If neither option is specified, the configure script 1051will try to guess whether the <code>.init_array</code> and 1052<code>.fini_array</code> sections are supported and, if they are, use them. 1053</p> 1054</dd> 1055<dt><code>--enable-link-mutex</code></dt> 1056<dd><p>When building GCC, use a mutex to avoid linking the compilers for 1057multiple languages at the same time, to avoid thrashing on build 1058systems with limited free memory. The default is not to use such a mutex. 1059</p> 1060</dd> 1061<dt><code>--enable-maintainer-mode</code></dt> 1062<dd><p>The build rules that regenerate the Autoconf and Automake output files as 1063well as the GCC master message catalog <samp>gcc.pot</samp> are normally 1064disabled. This is because it can only be rebuilt if the complete source 1065tree is present. If you have changed the sources and want to rebuild the 1066catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable 1067this. Note that you need a recent version of the <code>gettext</code> tools 1068to do so. 1069</p> 1070</dd> 1071<dt><code>--disable-bootstrap</code></dt> 1072<dd><p>For a native build, the default configuration is to perform 1073a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked, 1074testing that GCC can compile itself correctly. If you want to disable 1075this process, you can configure with <samp>--disable-bootstrap</samp>. 1076</p> 1077</dd> 1078<dt><code>--enable-bootstrap</code></dt> 1079<dd><p>In special cases, you may want to perform a 3-stage build 1080even if the target and host triplets are different. 1081This is possible when the host can run code compiled for 1082the target (e.g. host is i686-linux, target is i486-linux). 1083Starting from GCC 4.2, to do this you have to configure explicitly 1084with <samp>--enable-bootstrap</samp>. 1085</p> 1086</dd> 1087<dt><code>--enable-generated-files-in-srcdir</code></dt> 1088<dd><p>Neither the .c and .h files that are generated from Bison and flex nor the 1089info manuals and man pages that are built from the .texi files are present 1090in the repository development tree. When building GCC from that development tree, 1091or from one of our snapshots, those generated files are placed in your 1092build directory, which allows for the source to be in a readonly 1093directory. 1094</p> 1095<p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those 1096generated files will go into the source directory. This is mainly intended 1097for generating release or prerelease tarballs of the GCC sources, since it 1098is not a requirement that the users of source releases to have flex, Bison, 1099or makeinfo. 1100</p> 1101</dd> 1102<dt><code>--enable-version-specific-runtime-libs</code></dt> 1103<dd><p>Specify 1104that runtime libraries should be installed in the compiler specific 1105subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places. In 1106addition, ‘<samp>libstdc++</samp>’’s include files will be installed into 1107<samp><var>libdir</var></samp> unless you overruled it by using 1108<samp>--with-gxx-include-dir=<var>dirname</var></samp>. Using this option is 1109particularly useful if you intend to use several versions of GCC in 1110parallel. This is currently supported by ‘<samp>libgfortran</samp>’, 1111‘<samp>libstdc++</samp>’, and ‘<samp>libobjc</samp>’. 1112</p> 1113</dd> 1114<dt><code><a name="WithAixSoname"></a>--with-aix-soname=‘<samp>aix</samp>’, ‘<samp>svr4</samp>’ or ‘<samp>both</samp>’</code></dt> 1115<dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code> 1116files as members of unversioned <code>Archive Library</code> files named 1117‘<samp>lib.a</samp>’) causes numerous headaches for package managers. However, 1118<code>Import Files</code> as members of <code>Archive Library</code> files allow for 1119<strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4, 1120where this is called the "SONAME". But as they prevent static linking, 1121<code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the 1122linker does search for ‘<samp>libNAME.so</samp>’ before ‘<samp>libNAME.a</samp>’ library 1123filenames with the ‘<samp>-lNAME</samp>’ linker flag. 1124</p> 1125<a name="AixLdCommand"></a><p>For detailed information please refer to the AIX 1126<a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld 1127Command</a> reference. 1128</p> 1129<p>As long as shared library creation is enabled, upon: 1130</p><dl compact="compact"> 1131<dt><code>--with-aix-soname=aix</code></dt> 1132<dt><code>--with-aix-soname=both</code></dt> 1133<dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created: 1134 </p><ul> 1135<li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1136 </li><li> with the <code>Shared Object</code> file as archive member named 1137 ‘<samp>libNAME.so.V</samp>’ (except for ‘<samp>libgcc_s</samp>’, where the <code>Shared 1138 Object</code> file is named ‘<samp>shr.o</samp>’ for backwards compatibility), which 1139 <ul class="no-bullet"> 1140<li>- is used for runtime loading from inside the ‘<samp>libNAME.a</samp>’ file 1141 </li><li>- is used for dynamic loading via 1142 <code>dlopen("libNAME.a(libNAME.so.V)", RTLD_MEMBER)</code> 1143 </li><li>- is used for shared linking 1144 </li><li>- is used for static linking, so no separate <code>Static Archive 1145 Library</code> file is needed 1146 </li></ul> 1147</li></ul> 1148</dd> 1149<dt><code>--with-aix-soname=both</code></dt> 1150<dt><code>--with-aix-soname=svr4</code></dt> 1151<dd><p>A (second) <code>Shared Archive Library</code> file is created: 1152 </p><ul> 1153<li> using the ‘<samp>libNAME.so.V</samp>’ filename scheme 1154 </li><li> with the <code>Shared Object</code> file as archive member named 1155 ‘<samp>shr.o</samp>’, which 1156 <ul class="no-bullet"> 1157<li>- is created with the <code>-G linker flag</code> 1158 </li><li>- has the <code>F_LOADONLY</code> flag set 1159 </li><li>- is used for runtime loading from inside the ‘<samp>libNAME.so.V</samp>’ file 1160 </li><li>- is used for dynamic loading via <code>dlopen("libNAME.so.V(shr.o)", 1161 RTLD_MEMBER)</code> 1162 </li></ul> 1163</li><li> with the <code>Import File</code> as archive member named ‘<samp>shr.imp</samp>’, 1164 which 1165 <ul class="no-bullet"> 1166<li>- refers to ‘<samp>libNAME.so.V(shr.o)</samp>’ as the "SONAME", to be recorded 1167 in the <code>Loader Section</code> of subsequent binaries 1168 </li><li>- indicates whether ‘<samp>libNAME.so.V(shr.o)</samp>’ is 32 or 64 bit 1169 </li><li>- lists all the public symbols exported by ‘<samp>lib.so.V(shr.o)</samp>’, 1170 eventually decorated with the <code>‘<samp>weak</samp>’ Keyword</code> 1171 </li><li>- is necessary for shared linking against ‘<samp>lib.so.V(shr.o)</samp>’ 1172 </li></ul> 1173</li></ul> 1174<p>A symbolic link using the ‘<samp>libNAME.so</samp>’ filename scheme is created: 1175 </p><ul> 1176<li> pointing to the ‘<samp>libNAME.so.V</samp>’ <code>Shared Archive Library</code> file 1177 </li><li> to permit the <code>ld Command</code> to find ‘<samp>lib.so.V(shr.imp)</samp>’ via 1178 the ‘<samp>-lNAME</samp>’ argument (requires <code>Runtime Linking</code> to be enabled) 1179 </li><li> to permit dynamic loading of ‘<samp>lib.so.V(shr.o)</samp>’ without the need 1180 to specify the version number via <code>dlopen("libNAME.so(shr.o)", 1181 RTLD_MEMBER)</code> 1182 </li></ul> 1183</dd> 1184</dl> 1185 1186<p>As long as static library creation is enabled, upon: 1187</p><dl compact="compact"> 1188<dt><code>--with-aix-soname=svr4</code></dt> 1189<dd><p>A <code>Static Archive Library</code> is created: 1190 </p><ul> 1191<li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1192 </li><li> with all the <code>Static Object</code> files as archive members, which 1193 <ul class="no-bullet"> 1194<li>- are used for static linking 1195 </li></ul> 1196</li></ul> 1197</dd> 1198</dl> 1199 1200<p>While the aix-soname=‘<samp>svr4</samp>’ option does not create <code>Shared Object</code> 1201files as members of unversioned <code>Archive Library</code> files any more, package 1202managers still are responsible to 1203<a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files 1204found as member of a previously installed unversioned <code>Archive Library</code> 1205file into the newly installed <code>Archive Library</code> file with the same 1206filename. 1207</p> 1208<p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code> 1209enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors, 1210requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to 1211break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags, 1212see “RS/6000 and PowerPC Options” in the main manual. 1213</p> 1214<p><samp>--with-aix-soname</samp> is currently supported by ‘<samp>libgcc_s</samp>’ only, so 1215this option is still experimental and not for normal use yet. 1216</p> 1217<p>Default is the traditional behavior <samp>--with-aix-soname=‘<samp>aix</samp>’</samp>. 1218</p> 1219</dd> 1220<dt><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1221<dd><p>Specify that only a particular subset of compilers and 1222their runtime libraries should be built. For a list of valid values for 1223<var>langN</var> you can issue the following command in the 1224<samp>gcc</samp> directory of your GCC source tree:<br> 1225</p><div class="smallexample"> 1226<pre class="smallexample">grep ^language= */config-lang.in 1227</pre></div> 1228<p>Currently, you can use any of the following: 1229<code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>, 1230<code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>. 1231Building the Ada compiler has special requirements, see below. 1232If you do not pass this flag, or specify the option <code>default</code>, then the 1233default languages available in the <samp>gcc</samp> sub-tree will be configured. 1234Ada, D, Go, Jit, and Objective-C++ are not default languages. LTO is not a 1235default language, but is built by default because <samp>--enable-lto</samp> is 1236enabled by default. The other languages are default languages. If 1237<code>all</code> is specified, then all available languages are built. An 1238exception is <code>jit</code> language, which requires 1239<samp>--enable-host-shared</samp> to be included with <code>all</code>. 1240</p> 1241</dd> 1242<dt><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1243<dd><p>Specify that a particular subset of compilers and their runtime 1244libraries should be built with the system C compiler during stage 1 of 1245the bootstrap process, rather than only in later stages with the 1246bootstrapped C compiler. The list of valid values is the same as for 1247<samp>--enable-languages</samp>, and the option <code>all</code> will select all 1248of the languages enabled by <samp>--enable-languages</samp>. This option is 1249primarily useful for GCC development; for instance, when a development 1250version of the compiler cannot bootstrap due to compiler bugs, or when 1251one is debugging front ends other than the C front end. When this 1252option is used, one can then build the target libraries for the 1253specified languages with the stage-1 compiler by using <code>make 1254stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler 1255for the specified languages using <code>make stage1-start check-gcc</code>. 1256</p> 1257</dd> 1258<dt><code>--disable-libada</code></dt> 1259<dd><p>Specify that the run-time libraries and tools used by GNAT should not 1260be built. This can be useful for debugging, or for compatibility with 1261previous Ada build procedures, when it was required to explicitly 1262do a ‘<samp>make -C gcc gnatlib_and_tools</samp>’. 1263</p> 1264</dd> 1265<dt><code>--disable-libsanitizer</code></dt> 1266<dd><p>Specify that the run-time libraries for the various sanitizers should 1267not be built. 1268</p> 1269</dd> 1270<dt><code>--disable-libssp</code></dt> 1271<dd><p>Specify that the run-time libraries for stack smashing protection 1272should not be built or linked against. On many targets library support 1273is provided by the C library instead. 1274</p> 1275</dd> 1276<dt><code>--disable-libquadmath</code></dt> 1277<dd><p>Specify that the GCC quad-precision math library should not be built. 1278On some systems, the library is required to be linkable when building 1279the Fortran front end, unless <samp>--disable-libquadmath-support</samp> 1280is used. 1281</p> 1282</dd> 1283<dt><code>--disable-libquadmath-support</code></dt> 1284<dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add 1285support for <code>libquadmath</code> on systems supporting it. 1286</p> 1287</dd> 1288<dt><code>--disable-libgomp</code></dt> 1289<dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library 1290should not be built. 1291</p> 1292</dd> 1293<dt><code>--disable-libvtv</code></dt> 1294<dd><p>Specify that the run-time libraries used by vtable verification 1295should not be built. 1296</p> 1297</dd> 1298<dt><code>--with-dwarf2</code></dt> 1299<dd><p>Specify that the compiler should 1300use DWARF 2 debugging information as the default. 1301</p> 1302</dd> 1303<dt><code>--with-advance-toolchain=<var>at</var></code></dt> 1304<dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the 1305header files, library files, and the dynamic linker from the Advance 1306Toolchain release <var>at</var> instead of the default versions that are 1307provided by the Linux distribution. In general, this option is 1308intended for the developers of GCC, and it is not intended for general 1309use. 1310</p> 1311</dd> 1312<dt><code>--enable-targets=all</code></dt> 1313<dt><code>--enable-targets=<var>target_list</var></code></dt> 1314<dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers. 1315These are compilers that are able to generate either 64-bit or 32-bit 1316code. Typically, the corresponding 32-bit target, e.g. 1317powerpc-linux for powerpc64-linux, only generates 32-bit code. This 1318option enables the 32-bit target to be a bi-arch compiler, which is 1319useful when you want a bi-arch compiler that defaults to 32-bit, and 1320you are building a bi-arch or multi-arch binutils in a combined tree. 1321On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64), 1322defaulted to o32. 1323Currently, this option only affects sparc-linux, powerpc-linux, x86-linux, 1324mips-linux and s390-linux. 1325</p> 1326</dd> 1327<dt><code>--enable-default-pie</code></dt> 1328<dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default. 1329</p> 1330</dd> 1331<dt><code>--enable-secureplt</code></dt> 1332<dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux. 1333See “RS/6000 and PowerPC Options” in the main manual 1334</p> 1335</dd> 1336<dt><code>--enable-default-ssp</code></dt> 1337<dd><p>Turn on <samp>-fstack-protector-strong</samp> by default. 1338</p> 1339</dd> 1340<dt><code>--enable-cld</code></dt> 1341<dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets. 1342See “i386 and x86-64 Options” in the main manual 1343</p> 1344</dd> 1345<dt><code>--enable-large-address-aware</code></dt> 1346<dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW 1347executables to be linked using the <samp>--large-address-aware</samp> 1348option, that enables the use of more than 2GB of memory. If GCC is 1349configured with this option, its effects can be reversed by passing the 1350<samp>-Wl,--disable-large-address-aware</samp> option to the so-configured 1351compiler driver. 1352</p> 1353</dd> 1354<dt><code>--enable-win32-registry</code></dt> 1355<dt><code>--enable-win32-registry=<var>key</var></code></dt> 1356<dt><code>--disable-win32-registry</code></dt> 1357<dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC 1358to look up installations paths in the registry using the following key: 1359</p> 1360<div class="smallexample"> 1361<pre class="smallexample"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code> 1362</pre></div> 1363 1364<p><var>key</var> defaults to GCC version number, and can be overridden by the 1365<samp>--enable-win32-registry=<var>key</var></samp> option. Vendors and distributors 1366who use custom installers are encouraged to provide a different key, 1367perhaps one comprised of vendor name and GCC version number, to 1368avoid conflict with existing installations. This feature is enabled 1369by default, and can be disabled by <samp>--disable-win32-registry</samp> 1370option. This option has no effect on the other hosts. 1371</p> 1372</dd> 1373<dt><code>--nfp</code></dt> 1374<dd><p>Specify that the machine does not have a floating point unit. This 1375option only applies to ‘<samp>m68k-sun-sunos<var>n</var></samp>’. On any other 1376system, <samp>--nfp</samp> has no effect. 1377</p> 1378</dd> 1379<dt><code>--enable-werror</code></dt> 1380<dt><code>--disable-werror</code></dt> 1381<dt><code>--enable-werror=yes</code></dt> 1382<dt><code>--enable-werror=no</code></dt> 1383<dd><p>When you specify this option, it controls whether certain files in the 1384compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later. 1385If you don’t specify it, <samp>-Werror</samp> is turned on for the main 1386development trunk. However it defaults to off for release branches and 1387final releases. The specific files which get <samp>-Werror</samp> are 1388controlled by the Makefiles. 1389</p> 1390</dd> 1391<dt><code>--enable-checking</code></dt> 1392<dt><code>--disable-checking</code></dt> 1393<dt><code>--enable-checking=<var>list</var></code></dt> 1394<dd><p>This option controls performing internal consistency checks in the compiler. 1395It does not change the generated code, but adds error checking of the 1396requested complexity. This slows down the compiler and may only work 1397properly if you are building the compiler with GCC. 1398</p> 1399<p>When the option is not specified, the active set of checks depends on context. 1400Namely, bootstrap stage 1 defaults to ‘<samp>--enable-checking=yes</samp>’, builds 1401from release branches or release archives default to 1402‘<samp>--enable-checking=release</samp>’, and otherwise 1403‘<samp>--enable-checking=yes,extra</samp>’ is used. When the option is 1404specified without a <var>list</var>, the result is the same as 1405‘<samp>--enable-checking=yes</samp>’. Likewise, ‘<samp>--disable-checking</samp>’ is 1406equivalent to ‘<samp>--enable-checking=no</samp>’. 1407</p> 1408<p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (most common 1409checks ‘<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>’), ‘<samp>no</samp>’ 1410(no checks at all), ‘<samp>all</samp>’ (all but ‘<samp>valgrind</samp>’), ‘<samp>release</samp>’ 1411(cheapest checks ‘<samp>assert,runtime</samp>’) or ‘<samp>none</samp>’ (same as ‘<samp>no</samp>’). 1412‘<samp>release</samp>’ checks are always on and to disable them 1413‘<samp>--disable-checking</samp>’ or ‘<samp>--enable-checking=no[,<other checks>]</samp>’ 1414must be explicitly requested. Disabling assertions makes the compiler and 1415runtime slightly faster but increases the risk of undetected internal errors 1416causing wrong code to be generated. 1417</p> 1418<p>Individual checks can be enabled with these flags: ‘<samp>assert</samp>’, ‘<samp>df</samp>’, 1419‘<samp>extra</samp>’, ‘<samp>fold</samp>’, ‘<samp>gc</samp>’, ‘<samp>gcac</samp>’, ‘<samp>gimple</samp>’, 1420‘<samp>misc</samp>’, ‘<samp>rtl</samp>’, ‘<samp>rtlflag</samp>’, ‘<samp>runtime</samp>’, ‘<samp>tree</samp>’, 1421‘<samp>types</samp>’ and ‘<samp>valgrind</samp>’. ‘<samp>extra</samp>’ extends ‘<samp>misc</samp>’ 1422checking with extra checks that might affect code generation and should 1423therefore not differ between stage1 and later stages in bootstrap. 1424</p> 1425<p>The ‘<samp>valgrind</samp>’ check requires the external <code>valgrind</code> simulator, 1426available from <a href="http://valgrind.org/">http://valgrind.org/</a>. The ‘<samp>rtl</samp>’ checks are 1427expensive and the ‘<samp>df</samp>’, ‘<samp>gcac</samp>’ and ‘<samp>valgrind</samp>’ checks are very 1428expensive. 1429</p> 1430</dd> 1431<dt><code>--disable-stage1-checking</code></dt> 1432<dt><code>--enable-stage1-checking</code></dt> 1433<dt><code>--enable-stage1-checking=<var>list</var></code></dt> 1434<dd><p>This option affects only bootstrap build. If no <samp>--enable-checking</samp> 1435option is specified the stage1 compiler is built with ‘<samp>yes</samp>’ checking 1436enabled, otherwise the stage1 checking flags are the same as specified by 1437<samp>--enable-checking</samp>. To build the stage1 compiler with 1438different checking options use <samp>--enable-stage1-checking</samp>. 1439The list of checking options is the same as for <samp>--enable-checking</samp>. 1440If your system is too slow or too small to bootstrap a released compiler 1441with checking for stage1 enabled, you can use ‘<samp>--disable-stage1-checking</samp>’ 1442to disable checking for the stage1 compiler. 1443</p> 1444</dd> 1445<dt><code>--enable-coverage</code></dt> 1446<dt><code>--enable-coverage=<var>level</var></code></dt> 1447<dd><p>With this option, the compiler is built to collect self coverage 1448information, every time it is run. This is for internal development 1449purposes, and only works when the compiler is being built with gcc. The 1450<var>level</var> argument controls whether the compiler is built optimized or 1451not, values are ‘<samp>opt</samp>’ and ‘<samp>noopt</samp>’. For coverage analysis you 1452want to disable optimization, for performance analysis you want to 1453enable optimization. When coverage is enabled, the default level is 1454without optimization. 1455</p> 1456</dd> 1457<dt><code>--enable-gather-detailed-mem-stats</code></dt> 1458<dd><p>When this option is specified more detailed information on memory 1459allocation is gathered. This information is printed when using 1460<samp>-fmem-report</samp>. 1461</p> 1462</dd> 1463<dt><code>--enable-valgrind-annotations</code></dt> 1464<dd><p>Mark selected memory related operations in the compiler when run under 1465valgrind to suppress false positives. 1466</p> 1467</dd> 1468<dt><code>--enable-nls</code></dt> 1469<dt><code>--disable-nls</code></dt> 1470<dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS), 1471which lets GCC output diagnostics in languages other than American 1472English. Native Language Support is enabled by default if not doing a 1473canadian cross build. The <samp>--disable-nls</samp> option disables NLS. 1474</p> 1475</dd> 1476<dt><code>--with-included-gettext</code></dt> 1477<dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build 1478procedure to prefer its copy of GNU <code>gettext</code>. 1479</p> 1480</dd> 1481<dt><code>--with-catgets</code></dt> 1482<dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the 1483inferior <code>catgets</code> interface, the GCC build procedure normally 1484ignores <code>catgets</code> and instead uses GCC’s copy of the GNU 1485<code>gettext</code> library. The <samp>--with-catgets</samp> option causes the 1486build procedure to use the host’s <code>catgets</code> in this situation. 1487</p> 1488</dd> 1489<dt><code>--with-libiconv-prefix=<var>dir</var></code></dt> 1490<dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and 1491libiconv library files in <samp><var>dir</var>/lib</samp>. 1492</p> 1493</dd> 1494<dt><code>--enable-obsolete</code></dt> 1495<dd><p>Enable configuration for an obsoleted system. If you attempt to 1496configure GCC for a system (build, host, or target) which has been 1497obsoleted, and you do not specify this flag, configure will halt with an 1498error message. 1499</p> 1500<p>All support for systems which have been obsoleted in one release of GCC 1501is removed entirely in the next major release, unless someone steps 1502forward to maintain the port. 1503</p> 1504</dd> 1505<dt><code>--enable-decimal-float</code></dt> 1506<dt><code>--enable-decimal-float=yes</code></dt> 1507<dt><code>--enable-decimal-float=no</code></dt> 1508<dt><code>--enable-decimal-float=bid</code></dt> 1509<dt><code>--enable-decimal-float=dpd</code></dt> 1510<dt><code>--disable-decimal-float</code></dt> 1511<dd><p>Enable (or disable) support for the C decimal floating point extension 1512that is in the IEEE 754-2008 standard. This is enabled by default only 1513on PowerPC, i386, and x86_64 GNU/Linux systems. Other systems may also 1514support it, but require the user to specifically enable it. You can 1515optionally control which decimal floating point format is used (either 1516‘<samp>bid</samp>’ or ‘<samp>dpd</samp>’). The ‘<samp>bid</samp>’ (binary integer decimal) 1517format is default on i386 and x86_64 systems, and the ‘<samp>dpd</samp>’ 1518(densely packed decimal) format is default on PowerPC systems. 1519</p> 1520</dd> 1521<dt><code>--enable-fixed-point</code></dt> 1522<dt><code>--disable-fixed-point</code></dt> 1523<dd><p>Enable (or disable) support for C fixed-point arithmetic. 1524This option is enabled by default for some targets (such as MIPS) which 1525have hardware-support for fixed-point operations. On other targets, you 1526may enable this option manually. 1527</p> 1528</dd> 1529<dt><code>--with-long-double-128</code></dt> 1530<dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected 1531GNU/Linux architectures. If using <code>--without-long-double-128</code>, 1532<code>long double</code> will be by default 64-bit, the same as <code>double</code> type. 1533When neither of these configure options are used, the default will be 1534128-bit <code>long double</code> when built against GNU C Library 2.4 and later, 153564-bit <code>long double</code> otherwise. 1536</p> 1537</dd> 1538<dt><code>--with-long-double-format=ibm</code></dt> 1539<dt><code>--with-long-double-format=ieee</code></dt> 1540<dd><p>Specify whether <code>long double</code> uses the IBM extended double format 1541or the IEEE 128-bit floating point format on PowerPC Linux systems. 1542This configuration switch will only work on little endian PowerPC 1543Linux systems and on big endian 64-bit systems where the default cpu 1544is at least power7 (i.e. <samp>--with-cpu=power7</samp>, 1545<samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used). 1546</p> 1547<p>If you use the <samp>--with-long-double-64</samp> configuration option, 1548the <samp>--with-long-double-format=ibm</samp> and 1549<samp>--with-long-double-format=ieee</samp> options are ignored. 1550</p> 1551<p>The default <code>long double</code> format is to use IBM extended double. 1552Until all of the libraries are converted to use IEEE 128-bit floating 1553point, it is not recommended to use 1554<samp>--with-long-double-format=ieee</samp>. 1555</p> 1556<p>On little endian PowerPC Linux systems, if you explicitly set the 1557<code>long double</code> type, it will build multilibs to allow you to 1558select either <code>long double</code> format, unless you disable multilibs 1559with the <code>--disable-multilib</code> option. At present, 1560<code>long double</code> multilibs are not built on big endian PowerPC Linux 1561systems. If you are building multilibs, you will need to configure 1562the compiler using the <samp>--with-system-zlib</samp> option. 1563</p> 1564<p>If you do not set the <code>long double</code> type explicitly, no multilibs 1565will be generated. 1566</p> 1567</dd> 1568<dt><code>--enable-fdpic</code></dt> 1569<dd><p>On SH Linux systems, generate ELF FDPIC code. 1570</p> 1571</dd> 1572<dt><code>--with-gmp=<var>pathname</var></code></dt> 1573<dt><code>--with-gmp-include=<var>pathname</var></code></dt> 1574<dt><code>--with-gmp-lib=<var>pathname</var></code></dt> 1575<dt><code>--with-mpfr=<var>pathname</var></code></dt> 1576<dt><code>--with-mpfr-include=<var>pathname</var></code></dt> 1577<dt><code>--with-mpfr-lib=<var>pathname</var></code></dt> 1578<dt><code>--with-mpc=<var>pathname</var></code></dt> 1579<dt><code>--with-mpc-include=<var>pathname</var></code></dt> 1580<dt><code>--with-mpc-lib=<var>pathname</var></code></dt> 1581<dd><p>If you want to build GCC but do not have the GMP library, the MPFR 1582library and/or the MPC library installed in a standard location and 1583do not have their sources present in the GCC source tree then you 1584can explicitly specify the directory where they are installed 1585(‘<samp>--with-gmp=<var>gmpinstalldir</var></samp>’, 1586‘<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>’, 1587‘<samp>--with-mpc=<var>mpcinstalldir</var></samp>’). The 1588<samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for 1589<samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and 1590<samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>. Likewise the 1591<samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for 1592<samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and 1593<samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the 1594<samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for 1595<samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and 1596<samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>. If these 1597shorthand assumptions are not correct, you can use the explicit 1598include and lib options directly. You might also need to ensure the 1599shared libraries can be found by the dynamic linker when building and 1600using GCC, for example by setting the runtime shared library path 1601variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems). 1602</p> 1603<p>These flags are applicable to the host platform only. When building 1604a cross compiler, they will not be used to configure target libraries. 1605</p> 1606</dd> 1607<dt><code>--with-isl=<var>pathname</var></code></dt> 1608<dt><code>--with-isl-include=<var>pathname</var></code></dt> 1609<dt><code>--with-isl-lib=<var>pathname</var></code></dt> 1610<dd><p>If you do not have the isl library installed in a standard location and you 1611want to build GCC, you can explicitly specify the directory where it is 1612installed (‘<samp>--with-isl=<var>islinstalldir</var></samp>’). The 1613<samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for 1614<samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and 1615<samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this 1616shorthand assumption is not correct, you can use the explicit 1617include and lib options directly. 1618</p> 1619<p>These flags are applicable to the host platform only. When building 1620a cross compiler, they will not be used to configure target libraries. 1621</p> 1622</dd> 1623<dt><code>--with-stage1-ldflags=<var>flags</var></code></dt> 1624<dd><p>This option may be used to set linker flags to be used when linking 1625stage 1 of GCC. These are also used when linking GCC if configured with 1626<samp>--disable-bootstrap</samp>. If <samp>--with-stage1-libs</samp> is not set to a 1627value, then the default is ‘<samp>-static-libstdc++ -static-libgcc</samp>’, if 1628supported. 1629</p> 1630</dd> 1631<dt><code>--with-stage1-libs=<var>libs</var></code></dt> 1632<dd><p>This option may be used to set libraries to be used when linking stage 1 1633of GCC. These are also used when linking GCC if configured with 1634<samp>--disable-bootstrap</samp>. 1635</p> 1636</dd> 1637<dt><code>--with-boot-ldflags=<var>flags</var></code></dt> 1638<dd><p>This option may be used to set linker flags to be used when linking 1639stage 2 and later when bootstrapping GCC. If –with-boot-libs 1640is not is set to a value, then the default is 1641‘<samp>-static-libstdc++ -static-libgcc</samp>’. 1642</p> 1643</dd> 1644<dt><code>--with-boot-libs=<var>libs</var></code></dt> 1645<dd><p>This option may be used to set libraries to be used when linking stage 2 1646and later when bootstrapping GCC. 1647</p> 1648</dd> 1649<dt><code>--with-debug-prefix-map=<var>map</var></code></dt> 1650<dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when 1651building runtime libraries. ‘<samp><var>map</var></samp>’ is a space-separated 1652list of maps of the form ‘<samp><var>old</var>=<var>new</var></samp>’. 1653</p> 1654</dd> 1655<dt><code>--enable-linker-build-id</code></dt> 1656<dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final 1657links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp> 1658option), if the linker supports it. If you specify 1659<samp>--enable-linker-build-id</samp>, but your linker does not 1660support <samp>--build-id</samp> option, a warning is issued and the 1661<samp>--enable-linker-build-id</samp> option is ignored. The default is off. 1662</p> 1663</dd> 1664<dt><code>--with-linker-hash-style=<var>choice</var></code></dt> 1665<dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the 1666linker for all final links. <var>choice</var> can be one of 1667‘<samp>sysv</samp>’, ‘<samp>gnu</samp>’, and ‘<samp>both</samp>’ where ‘<samp>sysv</samp>’ is the default. 1668</p> 1669</dd> 1670<dt><code>--enable-gnu-unique-object</code></dt> 1671<dt><code>--disable-gnu-unique-object</code></dt> 1672<dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template 1673static data members and inline function local statics. Enabled by 1674default for a toolchain with an assembler that accepts it and 1675GLIBC 2.11 or above, otherwise disabled. 1676</p> 1677</dd> 1678<dt><code>--with-diagnostics-color=<var>choice</var></code></dt> 1679<dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp> 1680option (if not used explicitly on the command line). <var>choice</var> 1681can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1682where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ means that 1683<samp>-fdiagnostics-color=auto</samp> will be the default if <code>GCC_COLORS</code> 1684is present and non-empty in the environment, and 1685<samp>-fdiagnostics-color=never</samp> otherwise. 1686</p> 1687</dd> 1688<dt><code>--enable-lto</code></dt> 1689<dt><code>--disable-lto</code></dt> 1690<dd><p>Enable support for link-time optimization (LTO). This is enabled by 1691default, and may be disabled using <samp>--disable-lto</samp>. 1692</p> 1693</dd> 1694<dt><code>--enable-linker-plugin-configure-flags=FLAGS</code></dt> 1695<dt><code>--enable-linker-plugin-flags=FLAGS</code></dt> 1696<dd><p>By default, linker plugins (such as the LTO plugin) are built for the 1697host system architecture. For the case that the linker has a 1698different (but run-time compatible) architecture, these flags can be 1699specified to build plugins that are compatible to the linker. For 1700example, if you are building GCC for a 64-bit x86_64 1701(‘<samp>x86_64-pc-linux-gnu</samp>’) host system, but have a 32-bit x86 1702GNU/Linux (‘<samp>i686-pc-linux-gnu</samp>’) linker executable (which is 1703executable on the former system), you can configure GCC as follows for 1704getting compatible linker plugins: 1705</p> 1706<div class="smallexample"> 1707<pre class="smallexample">% <var>srcdir</var>/configure \ 1708 --host=x86_64-pc-linux-gnu \ 1709 --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \ 1710 --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib' 1711</pre></div> 1712 1713</dd> 1714<dt><code>--with-plugin-ld=<var>pathname</var></code></dt> 1715<dd><p>Enable an alternate linker to be used at link-time optimization (LTO) 1716link time when <samp>-fuse-linker-plugin</samp> is enabled. 1717This linker should have plugin support such as gold starting with 1718version 2.20 or GNU ld starting with version 2.21. 1719See <samp>-fuse-linker-plugin</samp> for details. 1720</p> 1721</dd> 1722<dt><code>--enable-canonical-system-headers</code></dt> 1723<dt><code>--disable-canonical-system-headers</code></dt> 1724<dd><p>Enable system header path canonicalization for <samp>libcpp</samp>. This can 1725produce shorter header file paths in diagnostics and dependency output 1726files, but these changed header paths may conflict with some compilation 1727environments. Enabled by default, and may be disabled using 1728<samp>--disable-canonical-system-headers</samp>. 1729</p> 1730</dd> 1731<dt><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></dt> 1732<dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it 1733will be version <var>major</var>.<var>minor</var> or later. Normally this can 1734be detected from the C library’s header files, but this option may be 1735needed when bootstrapping a cross toolchain without the header files 1736available for building the initial bootstrap compiler. 1737</p> 1738<p>If GCC is configured with some multilibs that use glibc and some that 1739do not, this option applies only to the multilibs that use glibc. 1740However, such configurations may not work well as not all the relevant 1741configuration in GCC is on a per-multilib basis. 1742</p> 1743</dd> 1744<dt><code>--enable-as-accelerator-for=<var>target</var></code></dt> 1745<dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>. 1746</p> 1747</dd> 1748<dt><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],…,<var>targetN</var>[=<var>pathN</var>]</code></dt> 1749<dd><p>Enable offloading to targets <var>target1</var>, …, <var>targetN</var>. 1750Offload compilers are expected to be already installed. Default search 1751path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by 1752specifying paths <var>path1</var>, …, <var>pathN</var>. 1753</p> 1754<div class="smallexample"> 1755<pre class="smallexample">% <var>srcdir</var>/configure \ 1756 --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none,hsa 1757</pre></div> 1758 1759<p>If ‘<samp>hsa</samp>’ is specified as one of the targets, the compiler will be 1760built with support for HSA GPU accelerators. Because the same 1761compiler will emit the accelerator code, no path should be specified. 1762</p> 1763</dd> 1764<dt><code>--with-hsa-runtime=<var>pathname</var></code></dt> 1765<dt><code>--with-hsa-runtime-include=<var>pathname</var></code></dt> 1766<dt><code>--with-hsa-runtime-lib=<var>pathname</var></code></dt> 1767<dd> 1768<p>If you configure GCC with HSA offloading but do not have the HSA 1769run-time library installed in a standard location then you can 1770explicitly specify the directory where they are installed. The 1771<samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option is a 1772shorthand for 1773<samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and 1774<samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>. 1775</p> 1776</dd> 1777<dt><code>--enable-cet</code></dt> 1778<dt><code>--disable-cet</code></dt> 1779<dd><p>Enable building target run-time libraries with control-flow 1780instrumentation, see <samp>-fcf-protection</samp> option. When 1781<code>--enable-cet</code> is specified target libraries are configured 1782to add <samp>-fcf-protection</samp> and, if needed, other target 1783specific options to a set of building options. 1784</p> 1785<p>The option is disabled by default. When <code>--enable-cet=auto</code> 1786is used, it is enabled on Linux/x86 if target binutils 1787supports <code>Intel CET</code> instructions and disabled otherwise. 1788In this case the target libraries are configured to get additional 1789<samp>-fcf-protection</samp> option. 1790</p> 1791</dd> 1792<dt><code>--with-riscv-attribute=‘<samp>yes</samp>’, ‘<samp>no</samp>’ or ‘<samp>default</samp>’</code></dt> 1793<dd><p>Generate RISC-V attribute by default, in order to record extra build 1794information in object. 1795</p> 1796<p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) 1797target if target binutils supported. 1798</p></dd> 1799</dl> 1800 1801<a name="Cross-Compiler-Specific-Options"></a> 1802<h4 class="subheading">Cross-Compiler-Specific Options</h4> 1803<p>The following options only apply to building cross compilers. 1804</p> 1805<dl compact="compact"> 1806<dt><code>--with-sysroot</code></dt> 1807<dt><code>--with-sysroot=<var>dir</var></code></dt> 1808<dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains 1809(a subset of) the root filesystem of the target operating system. 1810Target system headers, libraries and run-time object files will be 1811searched for in there. More specifically, this acts as if 1812<samp>--sysroot=<var>dir</var></samp> was added to the default options of the built 1813compiler. The specified directory is not copied into the 1814install tree, unlike the options <samp>--with-headers</samp> and 1815<samp>--with-libs</samp> that this option obsoletes. The default value, 1816in case <samp>--with-sysroot</samp> is not given an argument, is 1817<samp>${gcc_tooldir}/sys-root</samp>. If the specified directory is a 1818subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to 1819the GCC binaries if the installation tree is moved. 1820</p> 1821<p>This option affects the system root for the compiler used to build 1822target libraries (which runs on the build system) and the compiler newly 1823installed with <code>make install</code>; it does not affect the compiler which is 1824used to build GCC itself. 1825</p> 1826<p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1827option then the compiler will search that directory within <var>dirname</var> for 1828native system headers rather than the default <samp>/usr/include</samp>. 1829</p> 1830</dd> 1831<dt><code>--with-build-sysroot</code></dt> 1832<dt><code>--with-build-sysroot=<var>dir</var></code></dt> 1833<dd><p>Tells GCC to consider <var>dir</var> as the system root (see 1834<samp>--with-sysroot</samp>) while building target libraries, instead of 1835the directory specified with <samp>--with-sysroot</samp>. This option is 1836only useful when you are already using <samp>--with-sysroot</samp>. You 1837can use <samp>--with-build-sysroot</samp> when you are configuring with 1838<samp>--prefix</samp> set to a directory that is different from the one in 1839which you are installing GCC and your target libraries. 1840</p> 1841<p>This option affects the system root for the compiler used to build 1842target libraries (which runs on the build system); it does not affect 1843the compiler which is used to build GCC itself. 1844</p> 1845<p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1846option then the compiler will search that directory within <var>dirname</var> for 1847native system headers rather than the default <samp>/usr/include</samp>. 1848</p> 1849</dd> 1850<dt><code>--with-headers</code></dt> 1851<dt><code>--with-headers=<var>dir</var></code></dt> 1852<dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1853Specifies that target headers are available when building a cross compiler. 1854The <var>dir</var> argument specifies a directory which has the target include 1855files. These include files will be copied into the <samp>gcc</samp> install 1856directory. <em>This option with the <var>dir</var> argument is required</em> when 1857building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp> 1858doesn’t pre-exist. If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does 1859pre-exist, the <var>dir</var> argument may be omitted. <code>fixincludes</code> 1860will be run on these files to make them compatible with GCC. 1861</p> 1862</dd> 1863<dt><code>--without-headers</code></dt> 1864<dd><p>Tells GCC not use any target headers from a libc when building a cross 1865compiler. When crossing to GNU/Linux, you need the headers so GCC 1866can build the exception handling for libgcc. 1867</p> 1868</dd> 1869<dt><code>--with-libs</code></dt> 1870<dt><code>--with-libs="<var>dir1</var> <var>dir2</var> … <var>dirN</var>"</code></dt> 1871<dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1872Specifies a list of directories which contain the target runtime 1873libraries. These libraries will be copied into the <samp>gcc</samp> install 1874directory. If the directory list is omitted, this option has no 1875effect. 1876</p> 1877</dd> 1878<dt><code>--with-newlib</code></dt> 1879<dd><p>Specifies that ‘<samp>newlib</samp>’ is 1880being used as the target C library. This causes <code>__eprintf</code> to be 1881omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by 1882‘<samp>newlib</samp>’. 1883</p> 1884</dd> 1885<dt><code>--with-avrlibc</code></dt> 1886<dd><p>Specifies that ‘<samp>AVR-Libc</samp>’ is 1887being used as the target C library. This causes float support 1888functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on 1889the assumption that it will be provided by <samp>libm.a</samp>. For more 1890technical details, cf. <a href="http://gcc.gnu.org/PR54461">PR54461</a>. 1891This option is only supported for the AVR target. It is not supported for 1892RTEMS configurations, which currently use newlib. The option is 1893supported since version 4.7.2 and is the default in 4.8.0 and newer. 1894</p> 1895</dd> 1896<dt><code>--with-nds32-lib=<var>library</var></code></dt> 1897<dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>. 1898Currently, the valid <var>library</var> is ‘<samp>newlib</samp>’ or ‘<samp>mculib</samp>’. 1899This option is only supported for the NDS32 target. 1900</p> 1901</dd> 1902<dt><code>--with-build-time-tools=<var>dir</var></code></dt> 1903<dd><p>Specifies where to find the set of target tools (assembler, linker, etc.) 1904that will be used while building GCC itself. This option can be useful 1905if the directory layouts are different between the system you are building 1906GCC on, and the system where you will deploy it. 1907</p> 1908<p>For example, on an ‘<samp>ia64-hp-hpux</samp>’ system, you may have the GNU 1909assembler and linker in <samp>/usr/bin</samp>, and the native tools in a 1910different path, and build a toolchain that expects to find the 1911native tools in <samp>/usr/bin</samp>. 1912</p> 1913<p>When you use this option, you should ensure that <var>dir</var> includes 1914<code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>, 1915<code>ranlib</code> and <code>strip</code> if necessary, and possibly 1916<code>objdump</code>. Otherwise, GCC may use an inconsistent set of 1917tools. 1918</p></dd> 1919</dl> 1920 1921<a name="Overriding-configure-test-results"></a> 1922<h4 class="subsubheading">Overriding <code>configure</code> test results</h4> 1923 1924<p>Sometimes, it might be necessary to override the result of some 1925<code>configure</code> test, for example in order to ease porting to a new 1926system or work around a bug in a test. The toplevel <code>configure</code> 1927script provides three variables for this: 1928</p> 1929<dl compact="compact"> 1930<dt><code>build_configargs</code></dt> 1931<dd><a name="index-build_005fconfigargs"></a> 1932<p>The contents of this variable is passed to all build <code>configure</code> 1933scripts. 1934</p> 1935</dd> 1936<dt><code>host_configargs</code></dt> 1937<dd><a name="index-host_005fconfigargs"></a> 1938<p>The contents of this variable is passed to all host <code>configure</code> 1939scripts. 1940</p> 1941</dd> 1942<dt><code>target_configargs</code></dt> 1943<dd><a name="index-target_005fconfigargs"></a> 1944<p>The contents of this variable is passed to all target <code>configure</code> 1945scripts. 1946</p> 1947</dd> 1948</dl> 1949 1950<p>In order to avoid shell and <code>make</code> quoting issues for complex 1951overrides, you can pass a setting for <code>CONFIG_SITE</code> and set 1952variables in the site file. 1953</p> 1954<a name="Objective-C-Specific-Options"></a> 1955<h4 class="subheading">Objective-C-Specific Options</h4> 1956 1957<p>The following options apply to the build of the Objective-C runtime library. 1958</p> 1959<dl compact="compact"> 1960<dt><code>--enable-objc-gc</code></dt> 1961<dd><p>Specify that an additional variant of the GNU Objective-C runtime library 1962is built, using an external build of the Boehm-Demers-Weiser garbage 1963collector (<a href="http://www.hboehm.info/gc/">http://www.hboehm.info/gc/</a>). This library needs to be 1964available for each multilib variant, unless configured with 1965<samp>--enable-objc-gc=‘<samp>auto</samp>’</samp> in which case the build of the 1966additional runtime library is skipped when not available and the build 1967continues. 1968</p> 1969</dd> 1970<dt><code>--with-target-bdw-gc=<var>list</var></code></dt> 1971<dt><code>--with-target-bdw-gc-include=<var>list</var></code></dt> 1972<dt><code>--with-target-bdw-gc-lib=<var>list</var></code></dt> 1973<dd><p>Specify search directories for the garbage collector header files and 1974libraries. <var>list</var> is a comma separated list of key value pairs of the 1975form ‘<samp><var>multilibdir</var>=<var>path</var></samp>’, where the default multilib key 1976is named as ‘<samp>.</samp>’ (dot), or is omitted (e.g. 1977‘<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>’). 1978</p> 1979<p>The options <samp>--with-target-bdw-gc-include</samp> and 1980<samp>--with-target-bdw-gc-lib</samp> must always be specified together 1981for each multilib variant and they take precedence over 1982<samp>--with-target-bdw-gc</samp>. If <samp>--with-target-bdw-gc-include</samp> 1983is missing values for a multilib, then the value for the default 1984multilib is used (e.g. ‘<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>’ 1985‘<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>’). 1986If none of these options are specified, the library is assumed in 1987default locations. 1988</p></dd> 1989</dl> 1990 1991<a name="D-Specific-Options"></a> 1992<h4 class="subheading">D-Specific Options</h4> 1993 1994<p>The following options apply to the build of the D runtime library. 1995</p> 1996<dl compact="compact"> 1997<dt><code>--with-target-system-zlib</code></dt> 1998<dd><p>Use installed ‘<samp>zlib</samp>’ rather than that included with GCC. This needs 1999to be available for each multilib variant, unless configured with 2000<samp>--with-target-system-zlib=‘<samp>auto</samp>’</samp> in which case the GCC included 2001‘<samp>zlib</samp>’ is only used when the system installed library is not available. 2002</p></dd> 2003</dl> 2004 2005<hr /> 2006<p> 2007<p><a href="./index.html">Return to the GCC Installation page</a> 2008</p> 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020</body> 2021</html> 2022