1 This is configure.info, produced by makeinfo version 4.8 from 2 ./configure.texi. 3 4 INFO-DIR-SECTION GNU admin 5 START-INFO-DIR-ENTRY 6 * configure: (configure). The GNU configure and build system 7 END-INFO-DIR-ENTRY 8 9 This file documents the GNU configure and build system. 10 11 Copyright (C) 1998 Cygnus Solutions. 12 13 Permission is granted to make and distribute verbatim copies of this 14 manual provided the copyright notice and this permission notice are 15 preserved on all copies. 16 17 Permission is granted to copy and distribute modified versions of 18 this manual under the conditions for verbatim copying, provided that 19 the entire resulting derived work is distributed under the terms of a 20 permission notice identical to this one. 21 22 Permission is granted to copy and distribute translations of this 23 manual into another language, under the above conditions for modified 24 versions, except that this permission notice may be stated in a 25 translation approved by the Foundation. 26 27 28 File: configure.info, Node: Top, Next: Introduction, Up: (dir) 29 30 GNU configure and build system 31 ****************************** 32 33 The GNU configure and build system. 34 35 * Menu: 36 37 * Introduction:: Introduction. 38 * Getting Started:: Getting Started. 39 * Files:: Files. 40 * Configuration Names:: Configuration Names. 41 * Cross Compilation Tools:: Cross Compilation Tools. 42 * Canadian Cross:: Canadian Cross. 43 * Cygnus Configure:: Cygnus Configure. 44 * Multilibs:: Multilibs. 45 * FAQ:: Frequently Asked Questions. 46 * Index:: Index. 47 48 49 File: configure.info, Node: Introduction, Next: Getting Started, Prev: Top, Up: Top 50 51 1 Introduction 52 ************** 53 54 This document describes the GNU configure and build systems. It 55 describes how autoconf, automake, libtool, and make fit together. It 56 also includes a discussion of the older Cygnus configure system. 57 58 This document does not describe in detail how to use each of the 59 tools; see the respective manuals for that. Instead, it describes 60 which files the developer must write, which files are machine generated 61 and how they are generated, and where certain common problems should be 62 addressed. 63 64 This document draws on several sources, including the autoconf 65 manual by David MacKenzie (*note autoconf overview: (autoconf)Top.), 66 the automake manual by David MacKenzie and Tom Tromey (*note automake 67 overview: (automake)Top.), the libtool manual by Gordon Matzigkeit 68 (*note libtool overview: (libtool)Top.), and the Cygnus configure 69 manual by K. Richard Pixley. 70 71 * Menu: 72 73 * Goals:: Goals. 74 * Tools:: The tools. 75 * History:: History. 76 * Building:: Building. 77 78 79 File: configure.info, Node: Goals, Next: Tools, Up: Introduction 80 81 1.1 Goals 82 ========= 83 84 The GNU configure and build system has two main goals. 85 86 The first is to simplify the development of portable programs. The 87 system permits the developer to concentrate on writing the program, 88 simplifying many details of portability across Unix and even Windows 89 systems, and permitting the developer to describe how to build the 90 program using simple rules rather than complex Makefiles. 91 92 The second is to simplify the building of programs distributed as 93 source code. All programs are built using a simple, standardized, two 94 step process. The program builder need not install any special tools in 95 order to build the program. 96 97 98 File: configure.info, Node: Tools, Next: History, Prev: Goals, Up: Introduction 99 100 1.2 Tools 101 ========= 102 103 The GNU configure and build system is comprised of several different 104 tools. Program developers must build and install all of these tools. 105 106 People who just want to build programs from distributed sources 107 normally do not need any special tools beyond a Unix shell, a make 108 program, and a C compiler. 109 110 autoconf 111 provides a general portability framework, based on testing the 112 features of the host system at build time. 113 114 automake 115 a system for describing how to build a program, permitting the 116 developer to write a simplified `Makefile'. 117 118 libtool 119 a standardized approach to building shared libraries. 120 121 gettext 122 provides a framework for translation of text messages into other 123 languages; not really discussed in this document. 124 125 m4 126 autoconf requires the GNU version of m4; the standard Unix m4 does 127 not suffice. 128 129 perl 130 automake requires perl. 131 132 133 File: configure.info, Node: History, Next: Building, Prev: Tools, Up: Introduction 134 135 1.3 History 136 =========== 137 138 This is a very brief and probably inaccurate history. 139 140 As the number of Unix variants increased during the 1980s, it became 141 harder to write programs which could run on all variants. While it was 142 often possible to use `#ifdef' to identify particular systems, 143 developers frequently did not have access to every system, and the 144 characteristics of some systems changed from version to version. 145 146 By 1992, at least three different approaches had been developed: 147 * The Metaconfig program, by Larry Wall, Harlan Stenn, and Raphael 148 Manfredi. 149 150 * The Cygnus configure script, by K. Richard Pixley, and the gcc 151 configure script, by Richard Stallman. These use essentially the 152 same approach, and the developers communicated regularly. 153 154 * The autoconf program, by David MacKenzie. 155 156 The Metaconfig program is still used for Perl and a few other 157 programs. It is part of the Dist package. I do not know if it is 158 being developed. 159 160 In 1994, David MacKenzie and others modified autoconf to incorporate 161 all the features of Cygnus configure. Since then, there has been a 162 slow but steady conversion of GNU programs from Cygnus configure to 163 autoconf. gcc has been converted, eliminating the gcc configure script. 164 165 GNU autoconf was regularly maintained until late 1996. As of this 166 writing in June, 1998, it has no public maintainer. 167 168 Most programs are built using the make program, which requires the 169 developer to write Makefiles describing how to build the programs. 170 Since most programs are built in pretty much the same way, this led to a 171 lot of duplication. 172 173 The X Window system is built using the imake tool, which uses a 174 database of rules to eliminate the duplication. However, building a 175 tool which was developed using imake requires that the builder have 176 imake installed, violating one of the goals of the GNU system. 177 178 The new BSD make provides a standard library of Makefile fragments, 179 which permits developers to write very simple Makefiles. However, this 180 requires that the builder install the new BSD make program. 181 182 In 1994, David MacKenzie wrote the first version of automake, which 183 permitted writing a simple build description which was converted into a 184 Makefile which could be used by the standard make program. In 1995, Tom 185 Tromey completely rewrote automake in Perl, and he continues to enhance 186 it. 187 188 Various free packages built libraries, and by around 1995 several 189 included support to build shared libraries on various platforms. 190 However, there was no consistent approach. In early 1996, Gordon 191 Matzigkeit began working on libtool, which provided a standardized 192 approach to building shared libraries. This was integrated into 193 automake from the start. 194 195 The development of automake and libtool was driven by the GNITS 196 project, a group of GNU maintainers who designed standardized tools to 197 help meet the GNU coding standards. 198 199 200 File: configure.info, Node: Building, Prev: History, Up: Introduction 201 202 1.4 Building 203 ============ 204 205 Most readers of this document should already know how to build a tool by 206 running `configure' and `make'. This section may serve as a quick 207 introduction or reminder. 208 209 Building a tool is normally as simple as running `configure' 210 followed by `make'. You should normally run `configure' from an empty 211 directory, using some path to refer to the `configure' script in the 212 source directory. The directory in which you run `configure' is called 213 the "object directory". 214 215 In order to use a object directory which is different from the source 216 directory, you must be using the GNU version of `make', which has the 217 required `VPATH' support. Despite this restriction, using a different 218 object directory is highly recommended: 219 * It keeps the files generated during the build from cluttering up 220 your sources. 221 222 * It permits you to remove the built files by simply removing the 223 entire build directory. 224 225 * It permits you to build from the same sources with several sets of 226 configure options simultaneously. 227 228 If you don't have GNU `make', you will have to run `configure' in 229 the source directory. All GNU packages should support this; in 230 particular, GNU packages should not assume the presence of GNU `make'. 231 232 After running `configure', you can build the tools by running `make'. 233 234 To install the tools, run `make install'. Installing the tools will 235 copy the programs and any required support files to the "installation 236 directory". The location of the installation directory is controlled 237 by `configure' options, as described below. 238 239 In the Cygnus tree at present, the info files are built and 240 installed as a separate step. To build them, run `make info'. To 241 install them, run `make install-info'. The equivalent html files are 242 also built and installed in a separate step. To build the html files, 243 run `make html'. To install the html files run `make install-html'. 244 245 All `configure' scripts support a wide variety of options. The most 246 interesting ones are `--with' and `--enable' options which are 247 generally specific to particular tools. You can usually use the 248 `--help' option to get a list of interesting options for a particular 249 configure script. 250 251 The only generic options you are likely to use are the `--prefix' 252 and `--exec-prefix' options. These options are used to specify the 253 installation directory. 254 255 The directory named by the `--prefix' option will hold machine 256 independent files such as info files. 257 258 The directory named by the `--exec-prefix' option, which is normally 259 a subdirectory of the `--prefix' directory, will hold machine dependent 260 files such as executables. 261 262 The default for `--prefix' is `/usr/local'. The default for 263 `--exec-prefix' is the value used for `--prefix'. 264 265 The convention used in Cygnus releases is to use a `--prefix' option 266 of `/usr/cygnus/RELEASE', where RELEASE is the name of the release, and 267 to use a `--exec-prefix' option of `/usr/cygnus/RELEASE/H-HOST', where 268 HOST is the configuration name of the host system (*note Configuration 269 Names::). 270 271 Do not use either the source or the object directory as the 272 installation directory. That will just lead to confusion. 273 274 275 File: configure.info, Node: Getting Started, Next: Files, Prev: Introduction, Up: Top 276 277 2 Getting Started 278 ***************** 279 280 To start using the GNU configure and build system with your software 281 package, you must write three files, and you must run some tools to 282 manually generate additional files. 283 284 * Menu: 285 286 * Write configure.in:: Write configure.in. 287 * Write Makefile.am:: Write Makefile.am. 288 * Write acconfig.h:: Write acconfig.h. 289 * Generate files:: Generate files. 290 * Getting Started Example:: Example. 291 292 293 File: configure.info, Node: Write configure.in, Next: Write Makefile.am, Up: Getting Started 294 295 2.1 Write configure.in 296 ====================== 297 298 You must first write the file `configure.in'. This is an autoconf 299 input file, and the autoconf manual describes in detail what this file 300 should look like. 301 302 You will write tests in your `configure.in' file to check for 303 conditions that may change from one system to another, such as the 304 presence of particular header files or functions. 305 306 For example, not all systems support the `gettimeofday' function. 307 If you want to use the `gettimeofday' function when it is available, 308 and to use some other function when it is not, you would check for this 309 by putting `AC_CHECK_FUNCS(gettimeofday)' in `configure.in'. 310 311 When the configure script is run at build time, this will arrange to 312 define the preprocessor macro `HAVE_GETTIMEOFDAY' to the value 1 if the 313 `gettimeofday' function is available, and to not define the macro at 314 all if the function is not available. Your code can then use `#ifdef' 315 to test whether it is safe to call `gettimeofday'. 316 317 If you have an existing body of code, the `autoscan' program may 318 help identify potential portability problems, and hence configure tests 319 that you will want to use. *Note Invoking autoscan: (autoconf)Invoking 320 autoscan. 321 322 Another handy tool for an existing body of code is `ifnames'. This 323 will show you all the preprocessor conditionals that the code already 324 uses. *Note Invoking ifnames: (autoconf)Invoking ifnames. 325 326 Besides the portability tests which are specific to your particular 327 package, every `configure.in' file should contain the following macros. 328 329 `AC_INIT' 330 This macro takes a single argument, which is the name of a file in 331 your package. For example, `AC_INIT(foo.c)'. 332 333 `AC_PREREQ(VERSION)' 334 This macro is optional. It may be used to indicate the version of 335 `autoconf' that you are using. This will prevent users from 336 running an earlier version of `autoconf' and perhaps getting an 337 invalid `configure' script. For example, `AC_PREREQ(2.12)'. 338 339 `AM_INIT_AUTOMAKE' 340 This macro takes two arguments: the name of the package, and a 341 version number. For example, `AM_INIT_AUTOMAKE(foo, 1.0)'. (This 342 macro is not needed if you are not using automake). 343 344 `AM_CONFIG_HEADER' 345 This macro names the header file which will hold the preprocessor 346 macro definitions at run time. Normally this should be 347 `config.h'. Your sources would then use `#include "config.h"' to 348 include it. 349 350 This macro may optionally name the input file for that header 351 file; by default, this is `config.h.in', but that file name works 352 poorly on DOS filesystems. Therefore, it is often better to name 353 it explicitly as `config.in'. 354 355 This is what you should normally put in `configure.in': 356 AM_CONFIG_HEADER(config.h:config.in) 357 358 (If you are not using automake, use `AC_CONFIG_HEADER' rather than 359 `AM_CONFIG_HEADER'). 360 361 `AM_MAINTAINER_MODE' 362 This macro always appears in Cygnus configure scripts. Other 363 programs may or may not use it. 364 365 If this macro is used, the `--enable-maintainer-mode' option is 366 required to enable automatic rebuilding of generated files used by 367 the configure system. This of course requires that developers be 368 aware of, and use, that option. 369 370 If this macro is not used, then the generated files will always be 371 rebuilt automatically. This will cause problems if the wrong 372 versions of autoconf, automake, or others are in the builder's 373 `PATH'. 374 375 (If you are not using automake, you do not need to use this macro). 376 377 `AC_EXEEXT' 378 Either this macro or `AM_EXEEXT' always appears in Cygnus configure 379 files. Other programs may or may not use one of them. 380 381 This macro looks for the executable suffix used on the host 382 system. On Unix systems, this is the empty string. On Windows 383 systems, this is `.exe'. This macro directs automake to use the 384 executable suffix as appropriate when creating programs. This 385 macro does not take any arguments. 386 387 The `AC_EXEEXT' form is new, and is part of a Cygnus patch to 388 autoconf to support compiling with Visual C++. Older programs use 389 `AM_EXEEXT' instead. 390 391 (Programs which do not use automake use neither `AC_EXEEXT' nor 392 `AM_EXEEXT'). 393 394 `AC_PROG_CC' 395 If you are writing C code, you will normally want to use this 396 macro. It locates the C compiler to use. It does not take any 397 arguments. 398 399 However, if this `configure.in' file is for a library which is to 400 be compiled by a cross compiler which may not fully work, then you 401 will not want to use `AC_PROG_CC'. Instead, you will want to use a 402 variant which does not call the macro `AC_PROG_CC_WORKS'. Examples 403 can be found in various `configure.in' files for libraries that are 404 compiled with cross compilers, such as libiberty or libgloss. 405 This is essentially a bug in autoconf, and there will probably be 406 a better workaround at some point. 407 408 `AC_PROG_CXX' 409 If you are writing C++ code, you will want to use this macro. It 410 locates the C++ compiler to use. It does not take any arguments. 411 The same cross compiler comments apply as for `AC_PROG_CC'. 412 413 `AM_PROG_LIBTOOL' 414 If you want to build libraries, and you want to permit them to be 415 shared, or you want to link against libraries which were built 416 using libtool, then you will need this macro. This macro is 417 required in order to use libtool. 418 419 By default, this will cause all libraries to be built as shared 420 libraries. To prevent this-to change the default-use 421 `AM_DISABLE_SHARED' before `AM_PROG_LIBTOOL'. The configure 422 options `--enable-shared' and `--disable-shared' may be used to 423 override the default at build time. 424 425 `AC_DEFINE(_GNU_SOURCE)' 426 GNU packages should normally include this line before any other 427 feature tests. This defines the macro `_GNU_SOURCE' when 428 compiling, which directs the libc header files to provide the 429 standard GNU system interfaces including all GNU extensions. If 430 this macro is not defined, certain GNU extensions may not be 431 available. 432 433 `AC_OUTPUT' 434 This macro takes a list of file names which the configure process 435 should produce. This is normally a list of one or more `Makefile' 436 files in different directories. If your package lives entirely in 437 a single directory, you would use simply `AC_OUTPUT(Makefile)'. 438 If you also have, for example, a `lib' subdirectory, you would use 439 `AC_OUTPUT(Makefile lib/Makefile)'. 440 441 If you want to use locally defined macros in your `configure.in' 442 file, then you will need to write a `acinclude.m4' file which defines 443 them (if not using automake, this file is called `aclocal.m4'). 444 Alternatively, you can put separate macros in an `m4' subdirectory, and 445 put `ACLOCAL_AMFLAGS = -I m4' in your `Makefile.am' file so that the 446 `aclocal' program will be able to find them. 447 448 The different macro prefixes indicate which tool defines the macro. 449 Macros which start with `AC_' are part of autoconf. Macros which start 450 with `AM_' are provided by automake or libtool. 451 452 453 File: configure.info, Node: Write Makefile.am, Next: Write acconfig.h, Prev: Write configure.in, Up: Getting Started 454 455 2.2 Write Makefile.am 456 ===================== 457 458 You must write the file `Makefile.am'. This is an automake input file, 459 and the automake manual describes in detail what this file should look 460 like. 461 462 The automake commands in `Makefile.am' mostly look like variable 463 assignments in a `Makefile'. automake recognizes special variable 464 names, and automatically add make rules to the output as needed. 465 466 There will be one `Makefile.am' file for each directory in your 467 package. For each directory with subdirectories, the `Makefile.am' 468 file should contain the line 469 SUBDIRS = DIR DIR ... 470 where each DIR is the name of a subdirectory. 471 472 For each `Makefile.am', there should be a corresponding `Makefile' 473 in the `AC_OUTPUT' macro in `configure.in'. 474 475 Every `Makefile.am' written at Cygnus should contain the line 476 AUTOMAKE_OPTIONS = cygnus 477 This puts automake into Cygnus mode. See the automake manual for 478 details. 479 480 You may to include the version number of `automake' that you are 481 using on the `AUTOMAKE_OPTIONS' line. For example, 482 AUTOMAKE_OPTIONS = cygnus 1.3 483 This will prevent users from running an earlier version of 484 `automake' and perhaps getting an invalid `Makefile.in'. 485 486 If your package builds a program, then in the directory where that 487 program is built you will normally want a line like 488 bin_PROGRAMS = PROGRAM 489 where PROGRAM is the name of the program. You will then want a line 490 like 491 PROGRAM_SOURCES = FILE FILE ... 492 where each FILE is the name of a source file to link into the 493 program (e.g., `foo.c'). 494 495 If your package builds a library, and you do not want the library to 496 ever be built as a shared library, then in the directory where that 497 library is built you will normally want a line like 498 lib_LIBRARIES = libNAME.a 499 where `libNAME.a' is the name of the library. You will then want a 500 line like 501 libNAME_a_SOURCES = FILE FILE ... 502 where each FILE is the name of a source file to add to the library. 503 504 If your package builds a library, and you want to permit building the 505 library as a shared library, then in the directory where that library is 506 built you will normally want a line like 507 lib_LTLIBRARIES = libNAME.la 508 The use of `LTLIBRARIES', and the `.la' extension, indicate a 509 library to be built using libtool. As usual, you will then want a line 510 like 511 libNAME_la_SOURCES = FILE FILE ... 512 513 The strings `bin' and `lib' that appear above in `bin_PROGRAMS' and 514 `lib_LIBRARIES' are not arbitrary. They refer to particular 515 directories, which may be set by the `--bindir' and `--libdir' options 516 to `configure'. If those options are not used, the default values are 517 based on the `--prefix' or `--exec-prefix' options to `configure'. It 518 is possible to use other names if the program or library should be 519 installed in some other directory. 520 521 The `Makefile.am' file may also contain almost anything that may 522 appear in a normal `Makefile'. automake also supports many other 523 special variables, as well as conditionals. 524 525 See the automake manual for more information. 526 527 528 File: configure.info, Node: Write acconfig.h, Next: Generate files, Prev: Write Makefile.am, Up: Getting Started 529 530 2.3 Write acconfig.h 531 ==================== 532 533 If you are generating a portability header file, (i.e., you are using 534 `AM_CONFIG_HEADER' in `configure.in'), then you will have to write a 535 `acconfig.h' file. It will have to contain the following lines. 536 537 /* Name of package. */ 538 #undef PACKAGE 539 540 /* Version of package. */ 541 #undef VERSION 542 543 This requirement is really a bug in the system, and the requirement 544 may be eliminated at some later date. 545 546 The `acconfig.h' file will also similar comment and `#undef' lines 547 for any unusual macros in the `configure.in' file, including any macro 548 which appears in a `AC_DEFINE' macro. 549 550 In particular, if you are writing a GNU package and therefore include 551 `AC_DEFINE(_GNU_SOURCE)' in `configure.in' as suggested above, you will 552 need lines like this in `acconfig.h': 553 /* Enable GNU extensions. */ 554 #undef _GNU_SOURCE 555 556 Normally the `autoheader' program will inform you of any such 557 requirements by printing an error message when it is run. However, if 558 you do anything particular odd in your `configure.in' file, you will 559 have to make sure that the right entries appear in `acconfig.h', since 560 otherwise the results of the tests may not be available in the 561 `config.h' file which your code will use. 562 563 (Thee `PACKAGE' and `VERSION' lines are not required if you are not 564 using automake, and in that case you may not need a `acconfig.h' file 565 at all). 566 567 568 File: configure.info, Node: Generate files, Next: Getting Started Example, Prev: Write acconfig.h, Up: Getting Started 569 570 2.4 Generate files 571 ================== 572 573 Once you have written `configure.in', `Makefile.am', `acconfig.h', and 574 possibly `acinclude.m4', you must use autoconf and automake programs to 575 produce the first versions of the generated files. This is done by 576 executing the following sequence of commands. 577 578 aclocal 579 autoconf 580 autoheader 581 automake 582 583 The `aclocal' and `automake' commands are part of the automake 584 package, and the `autoconf' and `autoheader' commands are part of the 585 autoconf package. 586 587 If you are using a `m4' subdirectory for your macros, you will need 588 to use the `-I m4' option when you run `aclocal'. 589 590 If you are not using the Cygnus tree, use the `-a' option when 591 running `automake' command in order to copy the required support files 592 into your source directory. 593 594 If you are using libtool, you must build and install the libtool 595 package with the same `--prefix' and `--exec-prefix' options as you 596 used with the autoconf and automake packages. You must do this before 597 running any of the above commands. If you are not using the Cygnus 598 tree, you will need to run the `libtoolize' program to copy the libtool 599 support files into your directory. 600 601 Once you have managed to run these commands without getting any 602 errors, you should create a new empty directory, and run the `configure' 603 script which will have been created by `autoconf' with the 604 `--enable-maintainer-mode' option. This will give you a set of 605 Makefiles which will include rules to automatically rebuild all the 606 generated files. 607 608 After doing that, whenever you have changed some of the input files 609 and want to regenerated the other files, go to your object directory 610 and run `make'. Doing this is more reliable than trying to rebuild the 611 files manually, because there are complex order dependencies and it is 612 easy to forget something. 613 614 615 File: configure.info, Node: Getting Started Example, Prev: Generate files, Up: Getting Started 616 617 2.5 Example 618 =========== 619 620 Let's consider a trivial example. 621 622 Suppose we want to write a simple version of `touch'. Our program, 623 which we will call `poke', will take a single file name argument, and 624 use the `utime' system call to set the modification and access times of 625 the file to the current time. We want this program to be highly 626 portable. 627 628 We'll first see what this looks like without using autoconf and 629 automake, and then see what it looks like with them. 630 631 * Menu: 632 633 * Getting Started Example 1:: First Try. 634 * Getting Started Example 2:: Second Try. 635 * Getting Started Example 3:: Third Try. 636 * Generate Files in Example:: Generate Files. 637 638 639 File: configure.info, Node: Getting Started Example 1, Next: Getting Started Example 2, Up: Getting Started Example 640 641 2.5.1 First Try 642 --------------- 643 644 Here is our first try at `poke.c'. Note that we've written it without 645 ANSI/ISO C prototypes, since we want it to be highly portable. 646 647 #include <stdio.h> 648 #include <stdlib.h> 649 #include <sys/types.h> 650 #include <utime.h> 651 652 int 653 main (argc, argv) 654 int argc; 655 char **argv; 656 { 657 if (argc != 2) 658 { 659 fprintf (stderr, "Usage: poke file\n"); 660 exit (1); 661 } 662 663 if (utime (argv[1], NULL) < 0) 664 { 665 perror ("utime"); 666 exit (1); 667 } 668 669 exit (0); 670 } 671 672 We also write a simple `Makefile'. 673 674 CC = gcc 675 CFLAGS = -g -O2 676 677 all: poke 678 679 poke: poke.o 680 $(CC) -o poke $(CFLAGS) $(LDFLAGS) poke.o 681 682 So far, so good. 683 684 Unfortunately, there are a few problems. 685 686 On older Unix systems derived from BSD 4.3, the `utime' system call 687 does not accept a second argument of `NULL'. On those systems, we need 688 to pass a pointer to `struct utimbuf' structure. Unfortunately, even 689 older systems don't define that structure; on those systems, we need to 690 pass an array of two `long' values. 691 692 The header file `stdlib.h' was invented by ANSI C, and older systems 693 don't have a copy. We included it above to get a declaration of `exit'. 694 695 We can find some of these portability problems by running 696 `autoscan', which will create a `configure.scan' file which we can use 697 as a prototype for our `configure.in' file. I won't show the output, 698 but it will notice the potential problems with `utime' and `stdlib.h'. 699 700 In our `Makefile', we don't provide any way to install the program. 701 This doesn't matter much for such a simple example, but a real program 702 will need an `install' target. For that matter, we will also want a 703 `clean' target. 704 705 706 File: configure.info, Node: Getting Started Example 2, Next: Getting Started Example 3, Prev: Getting Started Example 1, Up: Getting Started Example 707 708 2.5.2 Second Try 709 ---------------- 710 711 Here is our second try at this program. 712 713 We modify `poke.c' to use preprocessor macros to control what 714 features are available. (I've cheated a bit by using the same macro 715 names which autoconf will use). 716 717 #include <stdio.h> 718 719 #ifdef STDC_HEADERS 720 #include <stdlib.h> 721 #endif 722 723 #include <sys/types.h> 724 725 #ifdef HAVE_UTIME_H 726 #include <utime.h> 727 #endif 728 729 #ifndef HAVE_UTIME_NULL 730 731 #include <time.h> 732 733 #ifndef HAVE_STRUCT_UTIMBUF 734 735 struct utimbuf 736 { 737 long actime; 738 long modtime; 739 }; 740 741 #endif 742 743 static int 744 utime_now (file) 745 char *file; 746 { 747 struct utimbuf now; 748 749 now.actime = now.modtime = time (NULL); 750 return utime (file, &now); 751 } 752 753 #define utime(f, p) utime_now (f) 754 755 #endif /* HAVE_UTIME_NULL */ 756 757 int 758 main (argc, argv) 759 int argc; 760 char **argv; 761 { 762 if (argc != 2) 763 { 764 fprintf (stderr, "Usage: poke file\n"); 765 exit (1); 766 } 767 768 if (utime (argv[1], NULL) < 0) 769 { 770 perror ("utime"); 771 exit (1); 772 } 773 774 exit (0); 775 } 776 777 Here is the associated `Makefile'. We've added support for the 778 preprocessor flags we use. We've also added `install' and `clean' 779 targets. 780 781 # Set this to your installation directory. 782 bindir = /usr/local/bin 783 784 # Uncomment this if you have the standard ANSI/ISO C header files. 785 # STDC_HDRS = -DSTDC_HEADERS 786 787 # Uncomment this if you have utime.h. 788 # UTIME_H = -DHAVE_UTIME_H 789 790 # Uncomment this if utime (FILE, NULL) works on your system. 791 # UTIME_NULL = -DHAVE_UTIME_NULL 792 793 # Uncomment this if struct utimbuf is defined in utime.h. 794 # UTIMBUF = -DHAVE_STRUCT_UTIMBUF 795 796 CC = gcc 797 CFLAGS = -g -O2 798 799 ALL_CFLAGS = $(STDC_HDRS) $(UTIME_H) $(UTIME_NULL) $(UTIMBUF) $(CFLAGS) 800 801 all: poke 802 803 poke: poke.o 804 $(CC) -o poke $(ALL_CFLAGS) $(LDFLAGS) poke.o 805 806 .c.o: 807 $(CC) -c $(ALL_CFLAGS) poke.c 808 809 install: poke 810 cp poke $(bindir)/poke 811 812 clean: 813 rm poke poke.o 814 815 Some problems with this approach should be clear. 816 817 Users who want to compile poke will have to know how `utime' works 818 on their systems, so that they can uncomment the `Makefile' correctly. 819 820 The installation is done using `cp', but many systems have an 821 `install' program which may be used, and which supports optional 822 features such as stripping debugging information out of the installed 823 binary. 824 825 The use of `Makefile' variables like `CC', `CFLAGS' and `LDFLAGS' 826 follows the requirements of the GNU standards. This is convenient for 827 all packages, since it reduces surprises for users. However, it is 828 easy to get the details wrong, and wind up with a slightly nonstandard 829 distribution. 830 831 832 File: configure.info, Node: Getting Started Example 3, Next: Generate Files in Example, Prev: Getting Started Example 2, Up: Getting Started Example 833 834 2.5.3 Third Try 835 --------------- 836 837 For our third try at this program, we will write a `configure.in' 838 script to discover the configuration features on the host system, rather 839 than requiring the user to edit the `Makefile'. We will also write a 840 `Makefile.am' rather than a `Makefile'. 841 842 The only change to `poke.c' is to add a line at the start of the 843 file: 844 #include "config.h" 845 846 The new `configure.in' file is as follows. 847 848 AC_INIT(poke.c) 849 AM_INIT_AUTOMAKE(poke, 1.0) 850 AM_CONFIG_HEADER(config.h:config.in) 851 AC_PROG_CC 852 AC_HEADER_STDC 853 AC_CHECK_HEADERS(utime.h) 854 AC_EGREP_HEADER(utimbuf, utime.h, AC_DEFINE(HAVE_STRUCT_UTIMBUF)) 855 AC_FUNC_UTIME_NULL 856 AC_OUTPUT(Makefile) 857 858 The first four macros in this file, and the last one, were described 859 above; see *Note Write configure.in::. If we omit these macros, then 860 when we run `automake' we will get a reminder that we need them. 861 862 The other macros are standard autoconf macros. 863 864 `AC_HEADER_STDC' 865 Check for standard C headers. 866 867 `AC_CHECK_HEADERS' 868 Check whether a particular header file exists. 869 870 `AC_EGREP_HEADER' 871 Check for a particular string in a particular header file, in this 872 case checking for `utimbuf' in `utime.h'. 873 874 `AC_FUNC_UTIME_NULL' 875 Check whether `utime' accepts a NULL second argument to set the 876 file change time to the current time. 877 878 See the autoconf manual for a more complete description. 879 880 The new `Makefile.am' file is as follows. Note how simple this is 881 compared to our earlier `Makefile'. 882 883 bin_PROGRAMS = poke 884 885 poke_SOURCES = poke.c 886 887 This means that we should build a single program name `poke'. It 888 should be installed in the binary directory, which we called `bindir' 889 earlier. The program `poke' is built from the source file `poke.c'. 890 891 We must also write a `acconfig.h' file. Besides `PACKAGE' and 892 `VERSION', which must be mentioned for all packages which use automake, 893 we must include `HAVE_STRUCT_UTIMBUF', since we mentioned it in an 894 `AC_DEFINE'. 895 896 /* Name of package. */ 897 #undef PACKAGE 898 899 /* Version of package. */ 900 #undef VERSION 901 902 /* Whether utime.h defines struct utimbuf. */ 903 #undef HAVE_STRUCT_UTIMBUF 904 905 906 File: configure.info, Node: Generate Files in Example, Prev: Getting Started Example 3, Up: Getting Started Example 907 908 2.5.4 Generate Files 909 -------------------- 910 911 We must now generate the other files, using the following commands. 912 913 aclocal 914 autoconf 915 autoheader 916 automake 917 918 When we run `autoheader', it will remind us of any macros we forgot 919 to add to `acconfig.h'. 920 921 When we run `automake', it will want to add some files to our 922 distribution. It will add them automatically if we use the 923 `--add-missing' option. 924 925 By default, `automake' will run in GNU mode, which means that it 926 will want us to create certain additional files; as of this writing, it 927 will want `NEWS', `README', `AUTHORS', and `ChangeLog', all of which 928 are files which should appear in a standard GNU distribution. We can 929 either add those files, or run `automake' with the `--foreign' option. 930 931 Running these tools will generate the following files, all of which 932 are described in the next chapter. 933 934 * `aclocal.m4' 935 936 * `configure' 937 938 * `config.in' 939 940 * `Makefile.in' 941 942 * `stamp-h.in' 943 944 945 File: configure.info, Node: Files, Next: Configuration Names, Prev: Getting Started, Up: Top 946 947 3 Files 948 ******* 949 950 As was seen in the previous chapter, the GNU configure and build system 951 uses a number of different files. The developer must write a few files. 952 The others are generated by various tools. 953 954 The system is rather flexible, and can be used in many different 955 ways. In describing the files that it uses, I will describe the common 956 case, and mention some other cases that may arise. 957 958 * Menu: 959 960 * Developer Files:: Developer Files. 961 * Build Files:: Build Files. 962 * Support Files:: Support Files. 963 964 965 File: configure.info, Node: Developer Files, Next: Build Files, Up: Files 966 967 3.1 Developer Files 968 =================== 969 970 This section describes the files written or generated by the developer 971 of a package. 972 973 * Menu: 974 975 * Developer Files Picture:: Developer Files Picture. 976 * Written Developer Files:: Written Developer Files. 977 * Generated Developer Files:: Generated Developer Files. 978 979 980 File: configure.info, Node: Developer Files Picture, Next: Written Developer Files, Up: Developer Files 981 982 3.1.1 Developer Files Picture 983 ----------------------------- 984 985 Here is a picture of the files which are written by the developer, the 986 generated files which would be included with a complete source 987 distribution, and the tools which create those files. The file names 988 are plain text and the tool names are enclosed by `*' characters (e.g., 989 `autoheader' is the name of a tool, not the name of a file). 990 991 acconfig.h configure.in Makefile.am 992 | | | 993 | --------------+---------------------- | 994 | | | | | 995 v v | acinclude.m4 | | 996 *autoheader* | | v v 997 | | v --->*automake* 998 v |--->*aclocal* | | 999 config.in | | | v 1000 | v | Makefile.in 1001 | aclocal.m4--- 1002 | | 1003 v v 1004 *autoconf* 1005 | 1006 v 1007 configure 1008 1009 1010 File: configure.info, Node: Written Developer Files, Next: Generated Developer Files, Prev: Developer Files Picture, Up: Developer Files 1011 1012 3.1.2 Written Developer Files 1013 ----------------------------- 1014 1015 The following files would be written by the developer. 1016 1017 `configure.in' 1018 This is the configuration script. This script contains 1019 invocations of autoconf macros. It may also contain ordinary 1020 shell script code. This file will contain feature tests for 1021 portability issues. The last thing in the file will normally be 1022 an `AC_OUTPUT' macro listing which files to create when the 1023 builder runs the configure script. This file is always required 1024 when using the GNU configure system. *Note Write configure.in::. 1025 1026 `Makefile.am' 1027 This is the automake input file. It describes how the code should 1028 be built. It consists of definitions of automake variables. It 1029 may also contain ordinary Makefile targets. This file is only 1030 needed when using automake (newer tools normally use automake, but 1031 there are still older tools which have not been converted, in 1032 which the developer writes `Makefile.in' directly). *Note Write 1033 Makefile.am::. 1034 1035 `acconfig.h' 1036 When the configure script creates a portability header file, by 1037 using `AM_CONFIG_HEADER' (or, if not using automake, 1038 `AC_CONFIG_HEADER'), this file is used to describe macros which are 1039 not recognized by the `autoheader' command. This is normally a 1040 fairly uninteresting file, consisting of a collection of `#undef' 1041 lines with comments. Normally any call to `AC_DEFINE' in 1042 `configure.in' will require a line in this file. *Note Write 1043 acconfig.h::. 1044 1045 `acinclude.m4' 1046 This file is not always required. It defines local autoconf 1047 macros. These macros may then be used in `configure.in'. If you 1048 don't need any local autoconf macros, then you don't need this 1049 file at all. In fact, in general, you never need local autoconf 1050 macros, since you can put everything in `configure.in', but 1051 sometimes a local macro is convenient. 1052 1053 Newer tools may omit `acinclude.m4', and instead use a 1054 subdirectory, typically named `m4', and define `ACLOCAL_AMFLAGS = 1055 -I m4' in `Makefile.am' to force `aclocal' to look there for macro 1056 definitions. The macro definitions are then placed in separate 1057 files in that directory. 1058 1059 The `acinclude.m4' file is only used when using automake; in older 1060 tools, the developer writes `aclocal.m4' directly, if it is needed. 1061 1062 1063 File: configure.info, Node: Generated Developer Files, Prev: Written Developer Files, Up: Developer Files 1064 1065 3.1.3 Generated Developer Files 1066 ------------------------------- 1067 1068 The following files would be generated by the developer. 1069 1070 When using automake, these files are normally not generated manually 1071 after the first time. Instead, the generated `Makefile' contains rules 1072 to automatically rebuild the files as required. When 1073 `AM_MAINTAINER_MODE' is used in `configure.in' (the normal case in 1074 Cygnus code), the automatic rebuilding rules will only be defined if 1075 you configure using the `--enable-maintainer-mode' option. 1076 1077 When using automatic rebuilding, it is important to ensure that all 1078 the various tools have been built and installed on your `PATH'. Using 1079 automatic rebuilding is highly recommended, so much so that I'm not 1080 going to explain what you have to do if you don't use it. 1081 1082 `configure' 1083 This is the configure script which will be run when building the 1084 package. This is generated by `autoconf' from `configure.in' and 1085 `aclocal.m4'. This is a shell script. 1086 1087 `Makefile.in' 1088 This is the file which the configure script will turn into the 1089 `Makefile' at build time. This file is generated by `automake' 1090 from `Makefile.am'. If you aren't using automake, you must write 1091 this file yourself. This file is pretty much a normal `Makefile', 1092 with some configure substitutions for certain variables. 1093 1094 `aclocal.m4' 1095 This file is created by the `aclocal' program, based on the 1096 contents of `configure.in' and `acinclude.m4' (or, as noted in the 1097 description of `acinclude.m4' above, on the contents of an `m4' 1098 subdirectory). This file contains definitions of autoconf macros 1099 which `autoconf' will use when generating the file `configure'. 1100 These autoconf macros may be defined by you in `acinclude.m4' or 1101 they may be defined by other packages such as automake, libtool or 1102 gettext. If you aren't using automake, you will normally write 1103 this file yourself; in that case, if `configure.in' uses only 1104 standard autoconf macros, this file will not be needed at all. 1105 1106 `config.in' 1107 This file is created by `autoheader' based on `acconfig.h' and 1108 `configure.in'. At build time, the configure script will define 1109 some of the macros in it to create `config.h', which may then be 1110 included by your program. This permits your C code to use 1111 preprocessor conditionals to change its behaviour based on the 1112 characteristics of the host system. This file may also be called 1113 `config.h.in'. 1114 1115 `stamp.h-in' 1116 This rather uninteresting file, which I omitted from the picture, 1117 is generated by `automake'. It always contains the string 1118 `timestamp'. It is used as a timestamp file indicating whether 1119 `config.in' is up to date. Using a timestamp file means that 1120 `config.in' can be marked as up to date without actually changing 1121 its modification time. This is useful since `config.in' depends 1122 upon `configure.in', but it is easy to change `configure.in' in a 1123 way which does not affect `config.in'. 1124 1125 1126 File: configure.info, Node: Build Files, Next: Support Files, Prev: Developer Files, Up: Files 1127 1128 3.2 Build Files 1129 =============== 1130 1131 This section describes the files which are created at configure and 1132 build time. These are the files which somebody who builds the package 1133 will see. 1134 1135 Of course, the developer will also build the package. The 1136 distinction between developer files and build files is not that the 1137 developer does not see the build files, but that somebody who only 1138 builds the package does not have to worry about the developer files. 1139 1140 * Menu: 1141 1142 * Build Files Picture:: Build Files Picture. 1143 * Build Files Description:: Build Files Description. 1144 1145 1146 File: configure.info, Node: Build Files Picture, Next: Build Files Description, Up: Build Files 1147 1148 3.2.1 Build Files Picture 1149 ------------------------- 1150 1151 Here is a picture of the files which will be created at build time. 1152 `config.status' is both a created file and a shell script which is run 1153 to create other files, and the picture attempts to show that. 1154 1155 config.in *configure* Makefile.in 1156 | | | 1157 | v | 1158 | config.status | 1159 | | | 1160 *config.status*<======+==========>*config.status* 1161 | | 1162 v v 1163 config.h Makefile 1164 1165 1166 File: configure.info, Node: Build Files Description, Prev: Build Files Picture, Up: Build Files 1167 1168 3.2.2 Build Files Description 1169 ----------------------------- 1170 1171 This is a description of the files which are created at build time. 1172 1173 `config.status' 1174 The first step in building a package is to run the `configure' 1175 script. The `configure' script will create the file 1176 `config.status', which is itself a shell script. When you first 1177 run `configure', it will automatically run `config.status'. An 1178 `Makefile' derived from an automake generated `Makefile.in' will 1179 contain rules to automatically run `config.status' again when 1180 necessary to recreate certain files if their inputs change. 1181 1182 `Makefile' 1183 This is the file which make will read to build the program. The 1184 `config.status' script will transform `Makefile.in' into 1185 `Makefile'. 1186 1187 `config.h' 1188 This file defines C preprocessor macros which C code can use to 1189 adjust its behaviour on different systems. The `config.status' 1190 script will transform `config.in' into `config.h'. 1191 1192 `config.cache' 1193 This file did not fit neatly into the picture, and I omitted it. 1194 It is used by the `configure' script to cache results between 1195 runs. This can be an important speedup. If you modify 1196 `configure.in' in such a way that the results of old tests should 1197 change (perhaps you have added a new library to `LDFLAGS'), then 1198 you will have to remove `config.cache' to force the tests to be 1199 rerun. 1200 1201 The autoconf manual explains how to set up a site specific cache 1202 file. This can speed up running `configure' scripts on your 1203 system. 1204 1205 `stamp.h' 1206 This file, which I omitted from the picture, is similar to 1207 `stamp-h.in'. It is used as a timestamp file indicating whether 1208 `config.h' is up to date. This is useful since `config.h' depends 1209 upon `config.status', but it is easy for `config.status' to change 1210 in a way which does not affect `config.h'. 1211 1212 1213 File: configure.info, Node: Support Files, Prev: Build Files, Up: Files 1214 1215 3.3 Support Files 1216 ================= 1217 1218 The GNU configure and build system requires several support files to be 1219 included with your distribution. You do not normally need to concern 1220 yourself with these. If you are using the Cygnus tree, most are already 1221 present. Otherwise, they will be installed with your source by 1222 `automake' (with the `--add-missing' option) and `libtoolize'. 1223 1224 You don't have to put the support files in the top level directory. 1225 You can put them in a subdirectory, and use the `AC_CONFIG_AUX_DIR' 1226 macro in `configure.in' to tell `automake' and the `configure' script 1227 where they are. 1228 1229 In this section, I describe the support files, so that you can know 1230 what they are and why they are there. 1231 1232 `ABOUT-NLS' 1233 Added by automake if you are using gettext. This is a 1234 documentation file about the gettext project. 1235 1236 `ansi2knr.c' 1237 Used by an automake generated `Makefile' if you put `ansi2knr' in 1238 `AUTOMAKE_OPTIONS' in `Makefile.am'. This permits compiling ANSI 1239 C code with a K&R C compiler. 1240 1241 `ansi2knr.1' 1242 The man page which goes with `ansi2knr.c'. 1243 1244 `config.guess' 1245 A shell script which determines the configuration name for the 1246 system on which it is run. 1247 1248 `config.sub' 1249 A shell script which canonicalizes a configuration name entered by 1250 a user. 1251 1252 `elisp-comp' 1253 Used to compile Emacs LISP files. 1254 1255 `install-sh' 1256 A shell script which installs a program. This is used if the 1257 configure script can not find an install binary. 1258 1259 `ltconfig' 1260 Used by libtool. This is a shell script which configures libtool 1261 for the particular system on which it is used. 1262 1263 `ltmain.sh' 1264 Used by libtool. This is the actual libtool script which is used, 1265 after it is configured by `ltconfig' to build a library. 1266 1267 `mdate-sh' 1268 A shell script used by an automake generated `Makefile' to pretty 1269 print the modification time of a file. This is used to maintain 1270 version numbers for texinfo files. 1271 1272 `missing' 1273 A shell script used if some tool is missing entirely. This is 1274 used by an automake generated `Makefile' to avoid certain sorts of 1275 timestamp problems. 1276 1277 `mkinstalldirs' 1278 A shell script which creates a directory, including all parent 1279 directories. This is used by an automake generated `Makefile' 1280 during installation. 1281 1282 `texinfo.tex' 1283 Required if you have any texinfo files. This is used when 1284 converting Texinfo files into DVI using `texi2dvi' and TeX. 1285 1286 `ylwrap' 1287 A shell script used by an automake generated `Makefile' to run 1288 programs like `bison', `yacc', `flex', and `lex'. These programs 1289 default to producing output files with a fixed name, and the 1290 `ylwrap' script runs them in a subdirectory to avoid file name 1291 conflicts when using a parallel make program. 1292 1293 1294 File: configure.info, Node: Configuration Names, Next: Cross Compilation Tools, Prev: Files, Up: Top 1295 1296 4 Configuration Names 1297 ********************* 1298 1299 The GNU configure system names all systems using a "configuration 1300 name". All such names used to be triplets (they may now contain four 1301 parts in certain cases), and the term "configuration triplet" is still 1302 seen. 1303 1304 * Menu: 1305 1306 * Configuration Name Definition:: Configuration Name Definition. 1307 * Using Configuration Names:: Using Configuration Names. 1308 1309 1310 File: configure.info, Node: Configuration Name Definition, Next: Using Configuration Names, Up: Configuration Names 1311 1312 4.1 Configuration Name Definition 1313 ================================= 1314 1315 This is a string of the form CPU-MANUFACTURER-OPERATING_SYSTEM. In 1316 some cases, this is extended to a four part form: 1317 CPU-MANUFACTURER-KERNEL-OPERATING_SYSTEM. 1318 1319 When using a configuration name in a configure option, it is normally 1320 not necessary to specify an entire name. In particular, the 1321 MANUFACTURER field is often omitted, leading to strings such as 1322 `i386-linux' or `sparc-sunos'. The shell script `config.sub' will 1323 translate these shortened strings into the canonical form. autoconf 1324 will arrange for `config.sub' to be run automatically when it is needed. 1325 1326 The fields of a configuration name are as follows: 1327 1328 CPU 1329 The type of processor. This is typically something like `i386' or 1330 `sparc'. More specific variants are used as well, such as 1331 `mipsel' to indicate a little endian MIPS processor. 1332 1333 MANUFACTURER 1334 A somewhat freeform field which indicates the manufacturer of the 1335 system. This is often simply `unknown'. Other common strings are 1336 `pc' for an IBM PC compatible system, or the name of a workstation 1337 vendor, such as `sun'. 1338 1339 OPERATING_SYSTEM 1340 The name of the operating system which is run on the system. This 1341 will be something like `solaris2.5' or `irix6.3'. There is no 1342 particular restriction on the version number, and strings like 1343 `aix4.1.4.0' are seen. For an embedded system, which has no 1344 operating system, this field normally indicates the type of object 1345 file format, such as `elf' or `coff'. 1346 1347 KERNEL 1348 This is used mainly for GNU/Linux. A typical GNU/Linux 1349 configuration name is `i586-pc-linux-gnulibc1'. In this case the 1350 kernel, `linux', is separated from the operating system, 1351 `gnulibc1'. 1352 1353 The shell script `config.guess' will normally print the correct 1354 configuration name for the system on which it is run. It does by 1355 running `uname' and by examining other characteristics of the system. 1356 1357 Because `config.guess' can normally determine the configuration name 1358 for a machine, it is normally only necessary to specify a configuration 1359 name when building a cross-compiler or when building using a 1360 cross-compiler. 1361 1362 1363 File: configure.info, Node: Using Configuration Names, Prev: Configuration Name Definition, Up: Configuration Names 1364 1365 4.2 Using Configuration Names 1366 ============================= 1367 1368 A configure script will sometimes have to make a decision based on a 1369 configuration name. You will need to do this if you have to compile 1370 code differently based on something which can not be tested using a 1371 standard autoconf feature test. 1372 1373 It is normally better to test for particular features, rather than to 1374 test for a particular system. This is because as Unix evolves, 1375 different systems copy features from one another. Even if you need to 1376 determine whether the feature is supported based on a configuration 1377 name, you should define a macro which describes the feature, rather than 1378 defining a macro which describes the particular system you are on. 1379 1380 Testing for a particular system is normally done using a case 1381 statement in `configure.in'. The case statement might look something 1382 like the following, assuming that `host' is a shell variable holding a 1383 canonical configuration name (which will be the case if `configure.in' 1384 uses the `AC_CANONICAL_HOST' or `AC_CANONICAL_SYSTEM' macro). 1385 1386 case "${host}" in 1387 i[3-7]86-*-linux-gnu*) do something ;; 1388 sparc*-sun-solaris2.[56789]*) do something ;; 1389 sparc*-sun-solaris*) do something ;; 1390 mips*-*-elf*) do something ;; 1391 esac 1392 1393 It is particularly important to use `*' after the operating system 1394 field, in order to match the version number which will be generated by 1395 `config.guess'. 1396 1397 In most cases you must be careful to match a range of processor 1398 types. For most processor families, a trailing `*' suffices, as in 1399 `mips*' above. For the i386 family, something along the lines of 1400 `i[3-7]86' suffices at present. For the m68k family, you will need 1401 something like `m68*'. Of course, if you do not need to match on the 1402 processor, it is simpler to just replace the entire field by a `*', as 1403 in `*-*-irix*'. 1404 1405 1406 File: configure.info, Node: Cross Compilation Tools, Next: Canadian Cross, Prev: Configuration Names, Up: Top 1407 1408 5 Cross Compilation Tools 1409 ************************* 1410 1411 The GNU configure and build system can be used to build "cross 1412 compilation" tools. A cross compilation tool is a tool which runs on 1413 one system and produces code which runs on another system. 1414 1415 * Menu: 1416 1417 * Cross Compilation Concepts:: Cross Compilation Concepts. 1418 * Host and Target:: Host and Target. 1419 * Using the Host Type:: Using the Host Type. 1420 * Specifying the Target:: Specifying the Target. 1421 * Using the Target Type:: Using the Target Type. 1422 * Cross Tools in the Cygnus Tree:: Cross Tools in the Cygnus Tree 1423 1424 1425 File: configure.info, Node: Cross Compilation Concepts, Next: Host and Target, Up: Cross Compilation Tools 1426 1427 5.1 Cross Compilation Concepts 1428 ============================== 1429 1430 A compiler which produces programs which run on a different system is a 1431 cross compilation compiler, or simply a "cross compiler". Similarly, 1432 we speak of cross assemblers, cross linkers, etc. 1433 1434 In the normal case, a compiler produces code which runs on the same 1435 system as the one on which the compiler runs. When it is necessary to 1436 distinguish this case from the cross compilation case, such a compiler 1437 is called a "native compiler". Similarly, we speak of native 1438 assemblers, etc. 1439 1440 Although the debugger is not strictly speaking a compilation tool, 1441 it is nevertheless meaningful to speak of a cross debugger: a debugger 1442 which is used to debug code which runs on another system. Everything 1443 that is said below about configuring cross compilation tools applies to 1444 the debugger as well. 1445 1446 1447 File: configure.info, Node: Host and Target, Next: Using the Host Type, Prev: Cross Compilation Concepts, Up: Cross Compilation Tools 1448 1449 5.2 Host and Target 1450 =================== 1451 1452 When building cross compilation tools, there are two different systems 1453 involved: the system on which the tools will run, and the system for 1454 which the tools generate code. 1455 1456 The system on which the tools will run is called the "host" system. 1457 1458 The system for which the tools generate code is called the "target" 1459 system. 1460 1461 For example, suppose you have a compiler which runs on a GNU/Linux 1462 system and generates ELF programs for a MIPS embedded system. In this 1463 case the GNU/Linux system is the host, and the MIPS ELF system is the 1464 target. Such a compiler could be called a GNU/Linux cross MIPS ELF 1465 compiler, or, equivalently, a `i386-linux-gnu' cross `mips-elf' 1466 compiler. 1467 1468 Naturally, most programs are not cross compilation tools. For those 1469 programs, it does not make sense to speak of a target. It only makes 1470 sense to speak of a target for tools like `gcc' or the `binutils' which 1471 actually produce running code. For example, it does not make sense to 1472 speak of the target of a tool like `bison' or `make'. 1473 1474 Most cross compilation tools can also serve as native tools. For a 1475 native compilation tool, it is still meaningful to speak of a target. 1476 For a native tool, the target is the same as the host. For example, for 1477 a GNU/Linux native compiler, the host is GNU/Linux, and the target is 1478 also GNU/Linux. 1479 1480 1481 File: configure.info, Node: Using the Host Type, Next: Specifying the Target, Prev: Host and Target, Up: Cross Compilation Tools 1482 1483 5.3 Using the Host Type 1484 ======================= 1485 1486 In almost all cases the host system is the system on which you run the 1487 `configure' script, and on which you build the tools (for the case when 1488 they differ, *note Canadian Cross::). 1489 1490 If your configure script needs to know the configuration name of the 1491 host system, and the package is not a cross compilation tool and 1492 therefore does not have a target, put `AC_CANONICAL_HOST' in 1493 `configure.in'. This macro will arrange to define a few shell 1494 variables when the `configure' script is run. 1495 1496 `host' 1497 The canonical configuration name of the host. This will normally 1498 be determined by running the `config.guess' shell script, although 1499 the user is permitted to override this by using an explicit 1500 `--host' option. 1501 1502 `host_alias' 1503 In the unusual case that the user used an explicit `--host' option, 1504 this will be the argument to `--host'. In the normal case, this 1505 will be the same as the `host' variable. 1506 1507 `host_cpu' 1508 `host_vendor' 1509 `host_os' 1510 The first three parts of the canonical configuration name. 1511 1512 The shell variables may be used by putting shell code in 1513 `configure.in'. For an example, see *Note Using Configuration Names::. 1514 1515 1516 File: configure.info, Node: Specifying the Target, Next: Using the Target Type, Prev: Using the Host Type, Up: Cross Compilation Tools 1517 1518 5.4 Specifying the Target 1519 ========================= 1520 1521 By default, the `configure' script will assume that the target is the 1522 same as the host. This is the more common case; for example, it leads 1523 to a native compiler rather than a cross compiler. 1524 1525 If you want to build a cross compilation tool, you must specify the 1526 target explicitly by using the `--target' option when you run 1527 `configure'. The argument to `--target' is the configuration name of 1528 the system for which you wish to generate code. *Note Configuration 1529 Names::. 1530 1531 For example, to build tools which generate code for a MIPS ELF 1532 embedded system, you would use `--target mips-elf'. 1533 1534 1535 File: configure.info, Node: Using the Target Type, Next: Cross Tools in the Cygnus Tree, Prev: Specifying the Target, Up: Cross Compilation Tools 1536 1537 5.5 Using the Target Type 1538 ========================= 1539 1540 When writing `configure.in' for a cross compilation tool, you will need 1541 to use information about the target. To do this, put 1542 `AC_CANONICAL_SYSTEM' in `configure.in'. 1543 1544 `AC_CANONICAL_SYSTEM' will look for a `--target' option and 1545 canonicalize it using the `config.sub' shell script. It will also run 1546 `AC_CANONICAL_HOST' (*note Using the Host Type::). 1547 1548 The target type will be recorded in the following shell variables. 1549 Note that the host versions of these variables will also be defined by 1550 `AC_CANONICAL_HOST'. 1551 1552 `target' 1553 The canonical configuration name of the target. 1554 1555 `target_alias' 1556 The argument to the `--target' option. If the user did not specify 1557 a `--target' option, this will be the same as `host_alias'. 1558 1559 `target_cpu' 1560 `target_vendor' 1561 `target_os' 1562 The first three parts of the canonical target configuration name. 1563 1564 Note that if `host' and `target' are the same string, you can assume 1565 a native configuration. If they are different, you can assume a cross 1566 configuration. 1567 1568 It is arguably possible for `host' and `target' to represent the 1569 same system, but for the strings to not be identical. For example, if 1570 `config.guess' returns `sparc-sun-sunos4.1.4', and somebody configures 1571 with `--target sparc-sun-sunos4.1', then the slight differences between 1572 the two versions of SunOS may be unimportant for your tool. However, 1573 in the general case it can be quite difficult to determine whether the 1574 differences between two configuration names are significant or not. 1575 Therefore, by convention, if the user specifies a `--target' option 1576 without specifying a `--host' option, it is assumed that the user wants 1577 to configure a cross compilation tool. 1578 1579 The variables `target' and `target_alias' should be handled 1580 differently. 1581 1582 In general, whenever the user may actually see a string, 1583 `target_alias' should be used. This includes anything which may appear 1584 in the file system, such as a directory name or part of a tool name. 1585 It also includes any tool output, unless it is clearly labelled as the 1586 canonical target configuration name. This permits the user to use the 1587 `--target' option to specify how the tool will appear to the outside 1588 world. 1589 1590 On the other hand, when checking for characteristics of the target 1591 system, `target' should be used. This is because a wide variety of 1592 `--target' options may map into the same canonical configuration name. 1593 You should not attempt to duplicate the canonicalization done by 1594 `config.sub' in your own code. 1595 1596 By convention, cross tools are installed with a prefix of the 1597 argument used with the `--target' option, also known as `target_alias' 1598 (*note Using the Target Type::). If the user does not use the 1599 `--target' option, and thus is building a native tool, no prefix is 1600 used. 1601 1602 For example, if gcc is configured with `--target mips-elf', then the 1603 installed binary will be named `mips-elf-gcc'. If gcc is configured 1604 without a `--target' option, then the installed binary will be named 1605 `gcc'. 1606 1607 The autoconf macro `AC_ARG_PROGRAM' will handle this for you. If 1608 you are using automake, no more need be done; the programs will 1609 automatically be installed with the correct prefixes. Otherwise, see 1610 the autoconf documentation for `AC_ARG_PROGRAM'. 1611 1612 1613 File: configure.info, Node: Cross Tools in the Cygnus Tree, Prev: Using the Target Type, Up: Cross Compilation Tools 1614 1615 5.6 Cross Tools in the Cygnus Tree 1616 ================================== 1617 1618 The Cygnus tree is used for various packages including gdb, the GNU 1619 binutils, and egcs. It is also, of course, used for Cygnus releases. 1620 1621 In the Cygnus tree, the top level `configure' script uses the old 1622 Cygnus configure system, not autoconf. The top level `Makefile.in' is 1623 written to build packages based on what is in the source tree, and 1624 supports building a large number of tools in a single 1625 `configure'/`make' step. 1626 1627 The Cygnus tree may be configured with a `--target' option. The 1628 `--target' option applies recursively to every subdirectory, and 1629 permits building an entire set of cross tools at once. 1630 1631 * Menu: 1632 1633 * Host and Target Libraries:: Host and Target Libraries. 1634 * Target Library Configure Scripts:: Target Library Configure Scripts. 1635 * Make Targets in Cygnus Tree:: Make Targets in Cygnus Tree. 1636 * Target libiberty:: Target libiberty 1637 1638 1639 File: configure.info, Node: Host and Target Libraries, Next: Target Library Configure Scripts, Up: Cross Tools in the Cygnus Tree 1640 1641 5.6.1 Host and Target Libraries 1642 ------------------------------- 1643 1644 The Cygnus tree distinguishes host libraries from target libraries. 1645 1646 Host libraries are built with the compiler used to build the programs 1647 which run on the host, which is called the host compiler. This includes 1648 libraries such as `bfd' and `tcl'. These libraries are built with the 1649 host compiler, and are linked into programs like the binutils or gcc 1650 which run on the host. 1651 1652 Target libraries are built with the target compiler. If gcc is 1653 present in the source tree, then the target compiler is the gcc that is 1654 built using the host compiler. Target libraries are libraries such as 1655 `newlib' and `libstdc++'. These libraries are not linked into the host 1656 programs, but are instead made available for use with programs built 1657 with the target compiler. 1658 1659 For the rest of this section, assume that gcc is present in the 1660 source tree, so that it will be used to build the target libraries. 1661 1662 There is a complication here. The configure process needs to know 1663 which compiler you are going to use to build a tool; otherwise, the 1664 feature tests will not work correctly. The Cygnus tree handles this by 1665 not configuring the target libraries until the target compiler is 1666 built. In order to permit everything to build using a single 1667 `configure'/`make', the configuration of the target libraries is 1668 actually triggered during the make step. 1669 1670 When the target libraries are configured, the `--target' option is 1671 not used. Instead, the `--host' option is used with the argument of 1672 the `--target' option for the overall configuration. If no `--target' 1673 option was used for the overall configuration, the `--host' option will 1674 be passed with the output of the `config.guess' shell script. Any 1675 `--build' option is passed down unchanged. 1676 1677 This translation of configuration options is done because since the 1678 target libraries are compiled with the target compiler, they are being 1679 built in order to run on the target of the overall configuration. By 1680 the definition of host, this means that their host system is the same as 1681 the target system of the overall configuration. 1682 1683 The same process is used for both a native configuration and a cross 1684 configuration. Even when using a native configuration, the target 1685 libraries will be configured and built using the newly built compiler. 1686 This is particularly important for the C++ libraries, since there is no 1687 reason to assume that the C++ compiler used to build the host tools (if 1688 there even is one) uses the same ABI as the g++ compiler which will be 1689 used to build the target libraries. 1690 1691 There is one difference between a native configuration and a cross 1692 configuration. In a native configuration, the target libraries are 1693 normally configured and built as siblings of the host tools. In a cross 1694 configuration, the target libraries are normally built in a subdirectory 1695 whose name is the argument to `--target'. This is mainly for 1696 historical reasons. 1697 1698 To summarize, running `configure' in the Cygnus tree configures all 1699 the host libraries and tools, but does not configure any of the target 1700 libraries. Running `make' then does the following steps: 1701 1702 * Build the host libraries. 1703 1704 * Build the host programs, including gcc. Note that we call gcc 1705 both a host program (since it runs on the host) and a target 1706 compiler (since it generates code for the target). 1707 1708 * Using the newly built target compiler, configure the target 1709 libraries. 1710 1711 * Build the target libraries. 1712 1713 The steps need not be done in precisely this order, since they are 1714 actually controlled by `Makefile' targets. 1715 1716 1717 File: configure.info, Node: Target Library Configure Scripts, Next: Make Targets in Cygnus Tree, Prev: Host and Target Libraries, Up: Cross Tools in the Cygnus Tree 1718 1719 5.6.2 Target Library Configure Scripts 1720 -------------------------------------- 1721 1722 There are a few things you must know in order to write a configure 1723 script for a target library. This is just a quick sketch, and beginners 1724 shouldn't worry if they don't follow everything here. 1725 1726 The target libraries are configured and built using a newly built 1727 target compiler. There may not be any startup files or libraries for 1728 this target compiler. In fact, those files will probably be built as 1729 part of some target library, which naturally means that they will not 1730 exist when your target library is configured. 1731 1732 This means that the configure script for a target library may not use 1733 any test which requires doing a link. This unfortunately includes many 1734 useful autoconf macros, such as `AC_CHECK_FUNCS'. autoconf macros 1735 which do a compile but not a link, such as `AC_CHECK_HEADERS', may be 1736 used. 1737 1738 This is a severe restriction, but normally not a fatal one, as target 1739 libraries can often assume the presence of other target libraries, and 1740 thus know which functions will be available. 1741 1742 As of this writing, the autoconf macro `AC_PROG_CC' does a link to 1743 make sure that the compiler works. This may fail in a target library, 1744 so target libraries must use a different set of macros to locate the 1745 compiler. See the `configure.in' file in a directory like `libiberty' 1746 or `libgloss' for an example. 1747 1748 As noted in the previous section, target libraries are sometimes 1749 built in directories which are siblings to the host tools, and are 1750 sometimes built in a subdirectory. The `--with-target-subdir' configure 1751 option will be passed when the library is configured. Its value will be 1752 an empty string if the target library is a sibling. Its value will be 1753 the name of the subdirectory if the target library is in a subdirectory. 1754 1755 If the overall build is not a native build (i.e., the overall 1756 configure used the `--target' option), then the library will be 1757 configured with the `--with-cross-host' option. The value of this 1758 option will be the host system of the overall build. Recall that the 1759 host system of the library will be the target of the overall build. If 1760 the overall build is a native build, the `--with-cross-host' option 1761 will not be used. 1762 1763 A library which can be built both standalone and as a target library 1764 may want to install itself into different directories depending upon the 1765 case. When built standalone, or when built native, the library should 1766 be installed in `$(libdir)'. When built as a target library which is 1767 not native, the library should be installed in `$(tooldir)/lib'. The 1768 `--with-cross-host' option may be used to distinguish these cases. 1769 1770 This same test of `--with-cross-host' may be used to see whether it 1771 is OK to use link tests in the configure script. If the 1772 `--with-cross-host' option is not used, then the library is being built 1773 either standalone or native, and a link should work. 1774 1775 1776 File: configure.info, Node: Make Targets in Cygnus Tree, Next: Target libiberty, Prev: Target Library Configure Scripts, Up: Cross Tools in the Cygnus Tree 1777 1778 5.6.3 Make Targets in Cygnus Tree 1779 --------------------------------- 1780 1781 The top level `Makefile' in the Cygnus tree defines targets for every 1782 known subdirectory. 1783 1784 For every subdirectory DIR which holds a host library or program, 1785 the `Makefile' target `all-DIR' will build that library or program. 1786 1787 There are dependencies among host tools. For example, building gcc 1788 requires first building gas, because the gcc build process invokes the 1789 target assembler. These dependencies are reflected in the top level 1790 `Makefile'. 1791 1792 For every subdirectory DIR which holds a target library, the 1793 `Makefile' target `configure-target-DIR' will configure that library. 1794 The `Makefile' target `all-target-DIR' will build that library. 1795 1796 Every `configure-target-DIR' target depends upon `all-gcc', since 1797 gcc, the target compiler, is required to configure the tool. Every 1798 `all-target-DIR' target depends upon the corresponding 1799 `configure-target-DIR' target. 1800 1801 There are several other targets which may be of interest for each 1802 directory: `install-DIR', `clean-DIR', and `check-DIR'. There are also 1803 corresponding `target' versions of these for the target libraries , 1804 such as `install-target-DIR'. 1805 1806 1807 File: configure.info, Node: Target libiberty, Prev: Make Targets in Cygnus Tree, Up: Cross Tools in the Cygnus Tree 1808 1809 5.6.4 Target libiberty 1810 ---------------------- 1811 1812 The `libiberty' subdirectory is currently a special case, in that it is 1813 the only directory which is built both using the host compiler and 1814 using the target compiler. 1815 1816 This is because the files in `libiberty' are used when building the 1817 host tools, and they are also incorporated into the `libstdc++' target 1818 library as support code. 1819 1820 This duality does not pose any particular difficulties. It means 1821 that there are targets for both `all-libiberty' and 1822 `all-target-libiberty'. 1823 1824 In a native configuration, when target libraries are not built in a 1825 subdirectory, the same objects are normally used as both the host build 1826 and the target build. This is normally OK, since libiberty contains 1827 only C code, and in a native configuration the results of the host 1828 compiler and the target compiler are normally interoperable. 1829 1830 Irix 6 is again an exception here, since the SGI native compiler 1831 defaults to using the `O32' ABI, and gcc defaults to using the `N32' 1832 ABI. On Irix 6, the target libraries are built in a subdirectory even 1833 for a native configuration, avoiding this problem. 1834 1835 There are currently no other libraries built for both the host and 1836 the target, but there is no conceptual problem with adding more. 1837 1838 1839 File: configure.info, Node: Canadian Cross, Next: Cygnus Configure, Prev: Cross Compilation Tools, Up: Top 1840 1841 6 Canadian Cross 1842 **************** 1843 1844 It is possible to use the GNU configure and build system to build a 1845 program which will run on a system which is different from the system on 1846 which the tools are built. In other words, it is possible to build 1847 programs using a cross compiler. 1848 1849 This is referred to as a "Canadian Cross". 1850 1851 * Menu: 1852 1853 * Canadian Cross Example:: Canadian Cross Example. 1854 * Canadian Cross Concepts:: Canadian Cross Concepts. 1855 * Build Cross Host Tools:: Build Cross Host Tools. 1856 * Build and Host Options:: Build and Host Options. 1857 * CCross not in Cygnus Tree:: Canadian Cross not in Cygnus Tree. 1858 * CCross in Cygnus Tree:: Canadian Cross in Cygnus Tree. 1859 * Supporting Canadian Cross:: Supporting Canadian Cross. 1860 1861 1862 File: configure.info, Node: Canadian Cross Example, Next: Canadian Cross Concepts, Up: Canadian Cross 1863 1864 6.1 Canadian Cross Example 1865 ========================== 1866 1867 Here is an example of a Canadian Cross. 1868 1869 While running on a GNU/Linux, you can build a program which will run 1870 on a Solaris system. You would use a GNU/Linux cross Solaris compiler 1871 to build the program. 1872 1873 Of course, you could not run the resulting program on your GNU/Linux 1874 system. You would have to copy it over to a Solaris system before you 1875 would run it. 1876 1877 Of course, you could also simply build the programs on the Solaris 1878 system in the first place. However, perhaps the Solaris system is not 1879 available for some reason; perhaps you actually don't have one, but you 1880 want to build the tools for somebody else to use. Or perhaps your 1881 GNU/Linux system is much faster than your Solaris system. 1882 1883 A Canadian Cross build is most frequently used when building 1884 programs to run on a non-Unix system, such as DOS or Windows. It may 1885 be simpler to configure and build on a Unix system than to support the 1886 configuration machinery on a non-Unix system. 1887 1888 1889 File: configure.info, Node: Canadian Cross Concepts, Next: Build Cross Host Tools, Prev: Canadian Cross Example, Up: Canadian Cross 1890 1891 6.2 Canadian Cross Concepts 1892 =========================== 1893 1894 When building a Canadian Cross, there are at least two different systems 1895 involved: the system on which the tools are being built, and the system 1896 on which the tools will run. 1897 1898 The system on which the tools are being built is called the "build" 1899 system. 1900 1901 The system on which the tools will run is called the host system. 1902 1903 For example, if you are building a Solaris program on a GNU/Linux 1904 system, as in the previous section, the build system would be GNU/Linux, 1905 and the host system would be Solaris. 1906 1907 It is, of course, possible to build a cross compiler using a Canadian 1908 Cross (i.e., build a cross compiler using a cross compiler). In this 1909 case, the system for which the resulting cross compiler generates code 1910 is called the target system. (For a more complete discussion of host 1911 and target systems, *note Host and Target::). 1912 1913 An example of building a cross compiler using a Canadian Cross would 1914 be building a Windows cross MIPS ELF compiler on a GNU/Linux system. In 1915 this case the build system would be GNU/Linux, the host system would be 1916 Windows, and the target system would be MIPS ELF. 1917 1918 The name Canadian Cross comes from the case when the build, host, and 1919 target systems are all different. At the time that these issues were 1920 all being hashed out, Canada had three national political parties. 1921 1922 1923 File: configure.info, Node: Build Cross Host Tools, Next: Build and Host Options, Prev: Canadian Cross Concepts, Up: Canadian Cross 1924 1925 6.3 Build Cross Host Tools 1926 ========================== 1927 1928 In order to configure a program for a Canadian Cross build, you must 1929 first build and install the set of cross tools you will use to build the 1930 program. 1931 1932 These tools will be build cross host tools. That is, they will run 1933 on the build system, and will produce code that runs on the host system. 1934 1935 It is easy to confuse the meaning of build and host here. Always 1936 remember that the build system is where you are doing the build, and the 1937 host system is where the resulting program will run. Therefore, you 1938 need a build cross host compiler. 1939 1940 In general, you must have a complete cross environment in order to do 1941 the build. This normally means a cross compiler, cross assembler, and 1942 so forth, as well as libraries and include files for the host system. 1943 1944 1945 File: configure.info, Node: Build and Host Options, Next: CCross not in Cygnus Tree, Prev: Build Cross Host Tools, Up: Canadian Cross 1946 1947 6.4 Build and Host Options 1948 ========================== 1949 1950 When you run `configure', you must use both the `--build' and `--host' 1951 options. 1952 1953 The `--build' option is used to specify the configuration name of 1954 the build system. This can normally be the result of running the 1955 `config.guess' shell script, and it is reasonable to use 1956 `--build=`config.guess`'. 1957 1958 The `--host' option is used to specify the configuration name of the 1959 host system. 1960 1961 As we explained earlier, `config.guess' is used to set the default 1962 value for the `--host' option (*note Using the Host Type::). We can 1963 now see that since `config.guess' returns the type of system on which 1964 it is run, it really identifies the build system. Since the host 1965 system is normally the same as the build system (i.e., people do not 1966 normally build using a cross compiler), it is reasonable to use the 1967 result of `config.guess' as the default for the host system when the 1968 `--host' option is not used. 1969 1970 It might seem that if the `--host' option were used without the 1971 `--build' option that the configure script could run `config.guess' to 1972 determine the build system, and presume a Canadian Cross if the result 1973 of `config.guess' differed from the `--host' option. However, for 1974 historical reasons, some configure scripts are routinely run using an 1975 explicit `--host' option, rather than using the default from 1976 `config.guess'. As noted earlier, it is difficult or impossible to 1977 reliably compare configuration names (*note Using the Target Type::). 1978 Therefore, by convention, if the `--host' option is used, but the 1979 `--build' option is not used, then the build system defaults to the 1980 host system. 1981 1982 1983 File: configure.info, Node: CCross not in Cygnus Tree, Next: CCross in Cygnus Tree, Prev: Build and Host Options, Up: Canadian Cross 1984 1985 6.5 Canadian Cross not in Cygnus Tree. 1986 ====================================== 1987 1988 If you are not using the Cygnus tree, you must explicitly specify the 1989 cross tools which you want to use to build the program. This is done by 1990 setting environment variables before running the `configure' script. 1991 1992 You must normally set at least the environment variables `CC', `AR', 1993 and `RANLIB' to the cross tools which you want to use to build. 1994 1995 For some programs, you must set additional cross tools as well, such 1996 as `AS', `LD', or `NM'. 1997 1998 You would set these environment variables to the build cross tools 1999 which you are going to use. 2000 2001 For example, if you are building a Solaris program on a GNU/Linux 2002 system, and your GNU/Linux cross Solaris compiler were named 2003 `solaris-gcc', then you would set the environment variable `CC' to 2004 `solaris-gcc'. 2005 2006 2007 File: configure.info, Node: CCross in Cygnus Tree, Next: Supporting Canadian Cross, Prev: CCross not in Cygnus Tree, Up: Canadian Cross 2008 2009 6.6 Canadian Cross in Cygnus Tree 2010 ================================= 2011 2012 This section describes configuring and building a Canadian Cross when 2013 using the Cygnus tree. 2014 2015 * Menu: 2016 2017 * Standard Cygnus CCross:: Building a Normal Program. 2018 * Cross Cygnus CCross:: Building a Cross Program. 2019 2020 2021 File: configure.info, Node: Standard Cygnus CCross, Next: Cross Cygnus CCross, Up: CCross in Cygnus Tree 2022 2023 6.6.1 Building a Normal Program 2024 ------------------------------- 2025 2026 When configuring a Canadian Cross in the Cygnus tree, all the 2027 appropriate environment variables are automatically set to `HOST-TOOL', 2028 where HOST is the value used for the `--host' option, and TOOL is the 2029 name of the tool (e.g., `gcc', `as', etc.). These tools must be on 2030 your `PATH'. 2031 2032 Adding a prefix of HOST will give the usual name for the build cross 2033 host tools. To see this, consider that when these cross tools were 2034 built, they were configured to run on the build system and to produce 2035 code for the host system. That is, they were configured with a 2036 `--target' option that is the same as the system which we are now 2037 calling the host. Recall that the default name for installed cross 2038 tools uses the target system as a prefix (*note Using the Target 2039 Type::). Since that is the system which we are now calling the host, 2040 HOST is the right prefix to use. 2041 2042 For example, if you configure with `--build=i386-linux-gnu' and 2043 `--host=solaris', then the Cygnus tree will automatically default to 2044 using the compiler `solaris-gcc'. You must have previously built and 2045 installed this compiler, probably by doing a build with no `--host' 2046 option and with a `--target' option of `solaris'. 2047 2048 2049 File: configure.info, Node: Cross Cygnus CCross, Prev: Standard Cygnus CCross, Up: CCross in Cygnus Tree 2050 2051 6.6.2 Building a Cross Program 2052 ------------------------------ 2053 2054 There are additional considerations if you want to build a cross 2055 compiler, rather than a native compiler, in the Cygnus tree using a 2056 Canadian Cross. 2057 2058 When you build a cross compiler using the Cygnus tree, then the 2059 target libraries will normally be built with the newly built target 2060 compiler (*note Host and Target Libraries::). However, this will not 2061 work when building with a Canadian Cross. This is because the newly 2062 built target compiler will be a program which runs on the host system, 2063 and therefore will not be able to run on the build system. 2064 2065 Therefore, when building a cross compiler with the Cygnus tree, you 2066 must first install a set of build cross target tools. These tools will 2067 be used when building the target libraries. 2068 2069 Note that this is not a requirement of a Canadian Cross in general. 2070 For example, it would be possible to build just the host cross target 2071 tools on the build system, to copy the tools to the host system, and to 2072 build the target libraries on the host system. The requirement for 2073 build cross target tools is imposed by the Cygnus tree, which expects 2074 to be able to build both host programs and target libraries in a single 2075 `configure'/`make' step. Because it builds these in a single step, it 2076 expects to be able to build the target libraries on the build system, 2077 which means that it must use a build cross target toolchain. 2078 2079 For example, suppose you want to build a Windows cross MIPS ELF 2080 compiler on a GNU/Linux system. You must have previously installed 2081 both a GNU/Linux cross Windows compiler and a GNU/Linux cross MIPS ELF 2082 compiler. 2083 2084 In order to build the Windows (configuration name `i386-cygwin32') 2085 cross MIPS ELF (configure name `mips-elf') compiler, you might execute 2086 the following commands (long command lines are broken across lines with 2087 a trailing backslash as a continuation character). 2088 2089 mkdir linux-x-cygwin32 2090 cd linux-x-cygwin32 2091 SRCDIR/configure --target i386-cygwin32 --prefix=INSTALLDIR \ 2092 --exec-prefix=INSTALLDIR/H-i386-linux 2093 make 2094 make install 2095 cd .. 2096 mkdir linux-x-mips-elf 2097 cd linux-x-mips-elf 2098 SRCDIR/configure --target mips-elf --prefix=INSTALLDIR \ 2099 --exec-prefix=INSTALLDIR/H-i386-linux 2100 make 2101 make install 2102 cd .. 2103 mkdir cygwin32-x-mips-elf 2104 cd cygwin32-x-mips-elf 2105 SRCDIR/configure --build=i386-linux-gnu --host=i386-cygwin32 \ 2106 --target=mips-elf --prefix=WININSTALLDIR \ 2107 --exec-prefix=WININSTALLDIR/H-i386-cygwin32 2108 make 2109 make install 2110 2111 You would then copy the contents of WININSTALLDIR over to the 2112 Windows machine, and run the resulting programs. 2113 2114 2115 File: configure.info, Node: Supporting Canadian Cross, Prev: CCross in Cygnus Tree, Up: Canadian Cross 2116 2117 6.7 Supporting Canadian Cross 2118 ============================= 2119 2120 If you want to make it possible to build a program you are developing 2121 using a Canadian Cross, you must take some care when writing your 2122 configure and make rules. Simple cases will normally work correctly. 2123 However, it is not hard to write configure and make tests which will 2124 fail in a Canadian Cross. 2125 2126 * Menu: 2127 2128 * CCross in Configure:: Supporting Canadian Cross in Configure Scripts. 2129 * CCross in Make:: Supporting Canadian Cross in Makefiles. 2130 2131 2132 File: configure.info, Node: CCross in Configure, Next: CCross in Make, Up: Supporting Canadian Cross 2133 2134 6.7.1 Supporting Canadian Cross in Configure Scripts 2135 ---------------------------------------------------- 2136 2137 In a `configure.in' file, after calling `AC_PROG_CC', you can find out 2138 whether this is a Canadian Cross configure by examining the shell 2139 variable `cross_compiling'. In a Canadian Cross, which means that the 2140 compiler is a cross compiler, `cross_compiling' will be `yes'. In a 2141 normal configuration, `cross_compiling' will be `no'. 2142 2143 You ordinarily do not need to know the type of the build system in a 2144 configure script. However, if you do need that information, you can get 2145 it by using the macro `AC_CANONICAL_SYSTEM', the same macro that is 2146 used to determine the target system. This macro will set the variables 2147 `build', `build_alias', `build_cpu', `build_vendor', and `build_os', 2148 which correspond to the similar `target' and `host' variables, except 2149 that they describe the build system. 2150 2151 When writing tests in `configure.in', you must remember that you 2152 want to test the host environment, not the build environment. 2153 2154 Macros like `AC_CHECK_FUNCS' which use the compiler will test the 2155 host environment. That is because the tests will be done by running the 2156 compiler, which is actually a build cross host compiler. If the 2157 compiler can find the function, that means that the function is present 2158 in the host environment. 2159 2160 Tests like `test -f /dev/ptyp0', on the other hand, will test the 2161 build environment. Remember that the configure script is running on the 2162 build system, not the host system. If your configure scripts examines 2163 files, those files will be on the build system. Whatever you determine 2164 based on those files may or may not be the case on the host system. 2165 2166 Most autoconf macros will work correctly for a Canadian Cross. The 2167 main exception is `AC_TRY_RUN'. This macro tries to compile and run a 2168 test program. This will fail in a Canadian Cross, because the program 2169 will be compiled for the host system, which means that it will not run 2170 on the build system. 2171 2172 The `AC_TRY_RUN' macro provides an optional argument to tell the 2173 configure script what to do in a Canadian Cross. If that argument is 2174 not present, you will get a warning when you run `autoconf': 2175 warning: AC_TRY_RUN called without default to allow cross compiling 2176 This tells you that the resulting `configure' script will not work 2177 with a Canadian Cross. 2178 2179 In some cases while it may better to perform a test at configure 2180 time, it is also possible to perform the test at run time. In such a 2181 case you can use the cross compiling argument to `AC_TRY_RUN' to tell 2182 your program that the test could not be performed at configure time. 2183 2184 There are a few other autoconf macros which will not work correctly 2185 with a Canadian Cross: a partial list is `AC_FUNC_GETPGRP', 2186 `AC_FUNC_SETPGRP', `AC_FUNC_SETVBUF_REVERSED', and 2187 `AC_SYS_RESTARTABLE_SYSCALLS'. The `AC_CHECK_SIZEOF' macro is 2188 generally not very useful with a Canadian Cross; it permits an optional 2189 argument indicating the default size, but there is no way to know what 2190 the correct default should be. 2191 2192 2193 File: configure.info, Node: CCross in Make, Prev: CCross in Configure, Up: Supporting Canadian Cross 2194 2195 6.7.2 Supporting Canadian Cross in Makefiles. 2196 --------------------------------------------- 2197 2198 The main Canadian Cross issue in a `Makefile' arises when you want to 2199 use a subsidiary program to generate code or data which you will then 2200 include in your real program. 2201 2202 If you compile this subsidiary program using `$(CC)' in the usual 2203 way, you will not be able to run it. This is because `$(CC)' will 2204 build a program for the host system, but the program is being built on 2205 the build system. 2206 2207 You must instead use a compiler for the build system, rather than the 2208 host system. In the Cygnus tree, this make variable `$(CC_FOR_BUILD)' 2209 will hold a compiler for the build system. 2210 2211 Note that you should not include `config.h' in a file you are 2212 compiling with `$(CC_FOR_BUILD)'. The `configure' script will build 2213 `config.h' with information for the host system. However, you are 2214 compiling the file using a compiler for the build system (a native 2215 compiler). Subsidiary programs are normally simple filters which do no 2216 user interaction, and it is normally possible to write them in a highly 2217 portable fashion so that the absence of `config.h' is not crucial. 2218 2219 The gcc `Makefile.in' shows a complex situation in which certain 2220 files, such as `rtl.c', must be compiled into both subsidiary programs 2221 run on the build system and into the final program. This approach may 2222 be of interest for advanced build system hackers. Note that the build 2223 system compiler is rather confusingly called `HOST_CC'. 2224 2225 2226 File: configure.info, Node: Cygnus Configure, Next: Multilibs, Prev: Canadian Cross, Up: Top 2227 2228 7 Cygnus Configure 2229 ****************** 2230 2231 The Cygnus configure script predates autoconf. All of its interesting 2232 features have been incorporated into autoconf. No new programs should 2233 be written to use the Cygnus configure script. 2234 2235 However, the Cygnus configure script is still used in a few places: 2236 at the top of the Cygnus tree and in a few target libraries in the 2237 Cygnus tree. Until those uses have been replaced with autoconf, some 2238 brief notes are appropriate here. This is not complete documentation, 2239 but it should be possible to use this as a guide while examining the 2240 scripts themselves. 2241 2242 * Menu: 2243 2244 * Cygnus Configure Basics:: Cygnus Configure Basics. 2245 * Cygnus Configure in C++ Libraries:: Cygnus Configure in C++ Libraries. 2246 2247 2248 File: configure.info, Node: Cygnus Configure Basics, Next: Cygnus Configure in C++ Libraries, Up: Cygnus Configure 2249 2250 7.1 Cygnus Configure Basics 2251 =========================== 2252 2253 Cygnus configure does not use any generated files; there is no program 2254 corresponding to `autoconf'. Instead, there is a single shell script 2255 named `configure' which may be found at the top of the Cygnus tree. 2256 This shell script was written by hand; it was not generated by 2257 autoconf, and it is incorrect, and indeed harmful, to run `autoconf' in 2258 the top level of a Cygnus tree. 2259 2260 Cygnus configure works in a particular directory by examining the 2261 file `configure.in' in that directory. That file is broken into four 2262 separate shell scripts. 2263 2264 The first is the contents of `configure.in' up to a line that starts 2265 with `# per-host:'. This is the common part. 2266 2267 The second is the rest of `configure.in' up to a line that starts 2268 with `# per-target:'. This is the per host part. 2269 2270 The third is the rest of `configure.in' up to a line that starts 2271 with `# post-target:'. This is the per target part. 2272 2273 The fourth is the remainder of `configure.in'. This is the post 2274 target part. 2275 2276 If any of these comment lines are missing, the corresponding shell 2277 script is empty. 2278 2279 Cygnus configure will first execute the common part. This must set 2280 the shell variable `srctrigger' to the name of a source file, to 2281 confirm that Cygnus configure is looking at the right directory. This 2282 may set the shell variables `package_makefile_frag' and 2283 `package_makefile_rules_frag'. 2284 2285 Cygnus configure will next set the `build' and `host' shell 2286 variables, and execute the per host part. This may set the shell 2287 variable `host_makefile_frag'. 2288 2289 Cygnus configure will next set the `target' variable, and execute 2290 the per target part. This may set the shell variable 2291 `target_makefile_frag'. 2292 2293 Any of these scripts may set the `subdirs' shell variable. This 2294 variable is a list of subdirectories where a `Makefile.in' file may be 2295 found. Cygnus configure will automatically look for a `Makefile.in' 2296 file in the current directory. The `subdirs' shell variable is not 2297 normally used, and I believe that the only directory which uses it at 2298 present is `newlib'. 2299 2300 For each `Makefile.in', Cygnus configure will automatically create a 2301 `Makefile' by adding definitions for `make' variables such as `host' 2302 and `target', and automatically editing the values of `make' variables 2303 such as `prefix' if they are present. 2304 2305 Also, if any of the `makefile_frag' shell variables are set, Cygnus 2306 configure will interpret them as file names relative to either the 2307 working directory or the source directory, and will read the contents of 2308 the file into the generated `Makefile'. The file contents will be read 2309 in after the first line in `Makefile.in' which starts with `####'. 2310 2311 These `Makefile' fragments are used to customize behaviour for a 2312 particular host or target. They serve to select particular files to 2313 compile, and to define particular preprocessor macros by providing 2314 values for `make' variables which are then used during compilation. 2315 Cygnus configure, unlike autoconf, normally does not do feature tests, 2316 and normally requires support to be added manually for each new host. 2317 2318 The `Makefile' fragment support is similar to the autoconf 2319 `AC_SUBST_FILE' macro. 2320 2321 After creating each `Makefile', the post target script will be run 2322 (i.e., it may be run several times). This script may further customize 2323 the `Makefile'. When it is run, the shell variable `Makefile' will 2324 hold the name of the `Makefile', including the appropriate directory 2325 component. 2326 2327 Like an autoconf generated `configure' script, Cygnus configure will 2328 create a file named `config.status' which, when run, will automatically 2329 recreate the configuration. The `config.status' file will simply 2330 execute the Cygnus configure script again with the appropriate 2331 arguments. 2332 2333 Any of the parts of `configure.in' may set the shell variables 2334 `files' and `links'. Cygnus configure will set up symlinks from the 2335 names in `links' to the files named in `files'. This is similar to the 2336 autoconf `AC_LINK_FILES' macro. 2337 2338 Finally, any of the parts of `configure.in' may set the shell 2339 variable `configdirs' to a set of subdirectories. If it is set, Cygnus 2340 configure will recursively run the configure process in each 2341 subdirectory. If the subdirectory uses Cygnus configure, it will 2342 contain a `configure.in' file but no `configure' file, in which case 2343 Cygnus configure will invoke itself recursively. If the subdirectory 2344 has a `configure' file, Cygnus configure assumes that it is an autoconf 2345 generated `configure' script, and simply invokes it directly. 2346 2347 2348 File: configure.info, Node: Cygnus Configure in C++ Libraries, Prev: Cygnus Configure Basics, Up: Cygnus Configure 2349 2350 7.2 Cygnus Configure in C++ Libraries 2351 ===================================== 2352 2353 The C++ library configure system, written by Per Bothner, deserves 2354 special mention. It uses Cygnus configure, but it does feature testing 2355 like that done by autoconf generated `configure' scripts. This 2356 approach is used in the libraries `libio', `libstdc++', and `libg++'. 2357 2358 Most of the `Makefile' information is written out by the shell 2359 script `libio/config.shared'. Each `configure.in' file sets certain 2360 shell variables, and then invokes `config.shared' to create two package 2361 `Makefile' fragments. These fragments are then incorporated into the 2362 resulting `Makefile' by the Cygnus configure script. 2363 2364 The file `_G_config.h' is created in the `libio' object directory by 2365 running the shell script `libio/gen-params'. This shell script uses 2366 feature tests to define macros and typedefs in `_G_config.h'. 2367 2368 2369 File: configure.info, Node: Multilibs, Next: FAQ, Prev: Cygnus Configure, Up: Top 2370 2371 8 Multilibs 2372 *********** 2373 2374 For some targets gcc may have different processor requirements depending 2375 upon command line options. An obvious example is the `-msoft-float' 2376 option supported on several processors. This option means that the 2377 floating point registers are not available, which means that floating 2378 point operations must be done by calling an emulation subroutine rather 2379 than by using machine instructions. 2380 2381 For such options, gcc is often configured to compile target libraries 2382 twice: once with `-msoft-float' and once without. When gcc compiles 2383 target libraries more than once, the resulting libraries are called 2384 "multilibs". 2385 2386 Multilibs are not really part of the GNU configure and build system, 2387 but we discuss them here since they require support in the `configure' 2388 scripts and `Makefile's used for target libraries. 2389 2390 * Menu: 2391 2392 * Multilibs in gcc:: Multilibs in gcc. 2393 * Multilibs in Target Libraries:: Multilibs in Target Libraries. 2394 2395 2396 File: configure.info, Node: Multilibs in gcc, Next: Multilibs in Target Libraries, Up: Multilibs 2397 2398 8.1 Multilibs in gcc 2399 ==================== 2400 2401 In gcc, multilibs are defined by setting the variable 2402 `MULTILIB_OPTIONS' in the target `Makefile' fragment. Several other 2403 `MULTILIB' variables may also be defined there. *Note The Target 2404 Makefile Fragment: (gcc)Target Fragment. 2405 2406 If you have built gcc, you can see what multilibs it uses by running 2407 it with the `-print-multi-lib' option. The output `.;' means that no 2408 multilibs are used. In general, the output is a sequence of lines, one 2409 per multilib. The first part of each line, up to the `;', is the name 2410 of the multilib directory. The second part is a list of compiler 2411 options separated by `@' characters. 2412 2413 Multilibs are built in a tree of directories. The top of the tree, 2414 represented by `.' in the list of multilib directories, is the default 2415 library to use when no special compiler options are used. The 2416 subdirectories of the tree hold versions of the library to use when 2417 particular compiler options are used. 2418 2419 2420 File: configure.info, Node: Multilibs in Target Libraries, Prev: Multilibs in gcc, Up: Multilibs 2421 2422 8.2 Multilibs in Target Libraries 2423 ================================= 2424 2425 The target libraries in the Cygnus tree are automatically built with 2426 multilibs. That means that each library is built multiple times. 2427 2428 This default is set in the top level `configure.in' file, by adding 2429 `--enable-multilib' to the list of arguments passed to configure when 2430 it is run for the target libraries (*note Host and Target Libraries::). 2431 2432 Each target library uses the shell script `config-ml.in', written by 2433 Doug Evans, to prepare to build target libraries. This shell script is 2434 invoked after the `Makefile' has been created by the `configure' 2435 script. If multilibs are not enabled, it does nothing, otherwise it 2436 modifies the `Makefile' to support multilibs. 2437 2438 The `config-ml.in' script makes one copy of the `Makefile' for each 2439 multilib in the appropriate subdirectory. When configuring in the 2440 source directory (which is not recommended), it will build a symlink 2441 tree of the sources in each subdirectory. 2442 2443 The `config-ml.in' script sets several variables in the various 2444 `Makefile's. The `Makefile.in' must have definitions for these 2445 variables already; `config-ml.in' simply changes the existing values. 2446 The `Makefile' should use default values for these variables which will 2447 do the right thing in the subdirectories. 2448 2449 `MULTISRCTOP' 2450 `config-ml.in' will set this to a sequence of `../' strings, where 2451 the number of strings is the number of multilib levels in the 2452 source tree. The default value should be the empty string. 2453 2454 `MULTIBUILDTOP' 2455 `config-ml.in' will set this to a sequence of `../' strings, where 2456 the number of strings is number of multilib levels in the object 2457 directory. The default value should be the empty string. This 2458 will differ from `MULTISRCTOP' when configuring in the source tree 2459 (which is not recommended). 2460 2461 `MULTIDIRS' 2462 In the top level `Makefile' only, `config-ml.in' will set this to 2463 the list of multilib subdirectories. The default value should be 2464 the empty string. 2465 2466 `MULTISUBDIR' 2467 `config-ml.in' will set this to the installed subdirectory name to 2468 use for this subdirectory, with a leading `/'. The default value 2469 shold be the empty string. 2470 2471 `MULTIDO' 2472 `MULTICLEAN' 2473 In the top level `Makefile' only, `config-ml.in' will set these 2474 variables to commands to use when doing a recursive make. These 2475 variables should both default to the string `true', so that by 2476 default nothing happens. 2477 2478 All references to the parent of the source directory should use the 2479 variable `MULTISRCTOP'. Instead of writing `$(srcdir)/..', you must 2480 write `$(srcdir)/$(MULTISRCTOP)..'. 2481 2482 Similarly, references to the parent of the object directory should 2483 use the variable `MULTIBUILDTOP'. 2484 2485 In the installation target, the libraries should be installed in the 2486 subdirectory `MULTISUBDIR'. Instead of installing 2487 `$(libdir)/libfoo.a', install `$(libdir)$(MULTISUBDIR)/libfoo.a'. 2488 2489 The `config-ml.in' script also modifies the top level `Makefile' to 2490 add `multi-do' and `multi-clean' targets which are used when building 2491 multilibs. 2492 2493 The default target of the `Makefile' should include the following 2494 command: 2495 @$(MULTIDO) $(FLAGS_TO_PASS) DO=all multi-do 2496 This assumes that `$(FLAGS_TO_PASS)' is defined as a set of 2497 variables to pass to a recursive invocation of `make'. This will build 2498 all the multilibs. Note that the default value of `MULTIDO' is `true', 2499 so by default this command will do nothing. It will only do something 2500 in the top level `Makefile' if multilibs were enabled. 2501 2502 The `install' target of the `Makefile' should include the following 2503 command: 2504 @$(MULTIDO) $(FLAGS_TO_PASS) DO=install multi-do 2505 2506 In general, any operation, other than clean, which should be 2507 performed on all the multilibs should use a `$(MULTIDO)' line, setting 2508 the variable `DO' to the target of each recursive call to `make'. 2509 2510 The `clean' targets (`clean', `mostlyclean', etc.) should use 2511 `$(MULTICLEAN)'. For example, the `clean' target should do this: 2512 @$(MULTICLEAN) DO=clean multi-clean 2513 2514 2515 File: configure.info, Node: FAQ, Next: Index, Prev: Multilibs, Up: Top 2516 2517 9 Frequently Asked Questions 2518 **************************** 2519 2520 Which do I run first, `autoconf' or `automake'? 2521 Except when you first add autoconf or automake support to a 2522 package, you shouldn't run either by hand. Instead, configure 2523 with the `--enable-maintainer-mode' option, and let `make' take 2524 care of it. 2525 2526 `autoconf' says something about undefined macros. 2527 This means that you have macros in your `configure.in' which are 2528 not defined by `autoconf'. You may be using an old version of 2529 `autoconf'; try building and installing a newer one. Make sure the 2530 newly installled `autoconf' is first on your `PATH'. Also, see 2531 the next question. 2532 2533 My `configure' script has stuff like `CY_GNU_GETTEXT' in it. 2534 This means that you have macros in your `configure.in' which should 2535 be defined in your `aclocal.m4' file, but aren't. This usually 2536 means that `aclocal' was not able to appropriate definitions of the 2537 macros. Make sure that you have installed all the packages you 2538 need. In particular, make sure that you have installed libtool 2539 (this is where `AM_PROG_LIBTOOL' is defined) and gettext (this is 2540 where `CY_GNU_GETTEXT' is defined, at least in the Cygnus version 2541 of gettext). 2542 2543 My `Makefile' has `@' characters in it. 2544 This may mean that you tried to use an autoconf substitution in 2545 your `Makefile.in' without adding the appropriate `AC_SUBST' call 2546 to your `configure' script. Or it may just mean that you need to 2547 rebuild `Makefile' in your build directory. To rebuild `Makefile' 2548 from `Makefile.in', run the shell script `config.status' with no 2549 arguments. If you need to force `configure' to run again, first 2550 run `config.status --recheck'. These runs are normally done 2551 automatically by `Makefile' targets, but if your `Makefile' has 2552 gotten messed up you'll need to help them along. 2553 2554 Why do I have to run both `config.status --recheck' and `config.status'? 2555 Normally, you don't; they will be run automatically by `Makefile' 2556 targets. If you do need to run them, use `config.status --recheck' 2557 to run the `configure' script again with the same arguments as the 2558 first time you ran it. Use `config.status' (with no arguments) to 2559 regenerate all files (`Makefile', `config.h', etc.) based on the 2560 results of the configure script. The two cases are separate 2561 because it isn't always necessary to regenerate all the files 2562 after running `config.status --recheck'. The `Makefile' targets 2563 generated by automake will use the environment variables 2564 `CONFIG_FILES' and `CONFIG_HEADERS' to only regenerate files as 2565 they are needed. 2566 2567 What is the Cygnus tree? 2568 The Cygnus tree is used for various packages including gdb, the GNU 2569 binutils, and egcs. It is also, of course, used for Cygnus 2570 releases. It is the build system which was developed at Cygnus, 2571 using the Cygnus configure script. It permits building many 2572 different packages with a single configure and make. The 2573 configure scripts in the tree are being converted to autoconf, but 2574 the general build structure remains intact. 2575 2576 Why do I have to keep rebuilding and reinstalling the tools? 2577 I know, it's a pain. Unfortunately, there are bugs in the tools 2578 themselves which need to be fixed, and each time that happens 2579 everybody who uses the tools need to reinstall new versions of 2580 them. I don't know if there is going to be a clever fix until the 2581 tools stabilize. 2582 2583 Why not just have a Cygnus tree `make' target to update the tools? 2584 The tools unfortunately need to be installed before they can be 2585 used. That means that they must be built using an appropriate 2586 prefix, and it seems unwise to assume that every configuration 2587 uses an appropriate prefix. It might be possible to make them 2588 work in place, or it might be possible to install them in some 2589 subdirectory; so far these approaches have not been implemented. 2590 2591 2592 File: configure.info, Node: Index, Prev: FAQ, Up: Top 2593 2594 Index 2595 ***** 2596 2597 [index] 2598 * Menu: 2599 2600 * --build option: Build and Host Options. 2601 (line 9) 2602 * --host option: Build and Host Options. 2603 (line 14) 2604 * --target option: Specifying the Target. 2605 (line 10) 2606 * _GNU_SOURCE: Write configure.in. (line 134) 2607 * AC_CANONICAL_HOST: Using the Host Type. (line 10) 2608 * AC_CANONICAL_SYSTEM: Using the Target Type. 2609 (line 6) 2610 * AC_CONFIG_HEADER: Write configure.in. (line 66) 2611 * AC_EXEEXT: Write configure.in. (line 86) 2612 * AC_INIT: Write configure.in. (line 38) 2613 * AC_OUTPUT: Write configure.in. (line 142) 2614 * AC_PREREQ: Write configure.in. (line 42) 2615 * AC_PROG_CC: Write configure.in. (line 103) 2616 * AC_PROG_CXX: Write configure.in. (line 117) 2617 * acconfig.h: Written Developer Files. 2618 (line 27) 2619 * acconfig.h, writing: Write acconfig.h. (line 6) 2620 * acinclude.m4: Written Developer Files. 2621 (line 37) 2622 * aclocal.m4: Generated Developer Files. 2623 (line 33) 2624 * AM_CONFIG_HEADER: Write configure.in. (line 53) 2625 * AM_DISABLE_SHARED: Write configure.in. (line 127) 2626 * AM_EXEEXT: Write configure.in. (line 86) 2627 * AM_INIT_AUTOMAKE: Write configure.in. (line 48) 2628 * AM_MAINTAINER_MODE: Write configure.in. (line 70) 2629 * AM_PROG_LIBTOOL: Write configure.in. (line 122) 2630 * AM_PROG_LIBTOOL in configure: FAQ. (line 19) 2631 * build option: Build and Host Options. 2632 (line 9) 2633 * building with a cross compiler: Canadian Cross. (line 6) 2634 * canadian cross: Canadian Cross. (line 6) 2635 * canadian cross in configure: CCross in Configure. (line 6) 2636 * canadian cross in cygnus tree: CCross in Cygnus Tree. 2637 (line 6) 2638 * canadian cross in makefile: CCross in Make. (line 6) 2639 * canadian cross, configuring: Build and Host Options. 2640 (line 6) 2641 * canonical system names: Configuration Names. (line 6) 2642 * config.cache: Build Files Description. 2643 (line 28) 2644 * config.h: Build Files Description. 2645 (line 23) 2646 * config.h.in: Generated Developer Files. 2647 (line 45) 2648 * config.in: Generated Developer Files. 2649 (line 45) 2650 * config.status: Build Files Description. 2651 (line 9) 2652 * config.status --recheck: FAQ. (line 40) 2653 * configuration names: Configuration Names. (line 6) 2654 * configuration triplets: Configuration Names. (line 6) 2655 * configure: Generated Developer Files. 2656 (line 21) 2657 * configure build system: Build and Host Options. 2658 (line 9) 2659 * configure host: Build and Host Options. 2660 (line 14) 2661 * configure target: Specifying the Target. 2662 (line 10) 2663 * configure.in: Written Developer Files. 2664 (line 9) 2665 * configure.in, writing: Write configure.in. (line 6) 2666 * configuring a canadian cross: Build and Host Options. 2667 (line 6) 2668 * cross compiler: Cross Compilation Concepts. 2669 (line 6) 2670 * cross compiler, building with: Canadian Cross. (line 6) 2671 * cross tools: Cross Compilation Tools. 2672 (line 6) 2673 * CY_GNU_GETTEXT in configure: FAQ. (line 19) 2674 * cygnus configure: Cygnus Configure. (line 6) 2675 * goals: Goals. (line 6) 2676 * history: History. (line 6) 2677 * host names: Configuration Names. (line 6) 2678 * host option: Build and Host Options. 2679 (line 14) 2680 * host system: Host and Target. (line 6) 2681 * host triplets: Configuration Names. (line 6) 2682 * HOST_CC: CCross in Make. (line 27) 2683 * libg++ configure: Cygnus Configure in C++ Libraries. 2684 (line 6) 2685 * libio configure: Cygnus Configure in C++ Libraries. 2686 (line 6) 2687 * libstdc++ configure: Cygnus Configure in C++ Libraries. 2688 (line 6) 2689 * Makefile: Build Files Description. 2690 (line 18) 2691 * Makefile, garbage characters: FAQ. (line 29) 2692 * Makefile.am: Written Developer Files. 2693 (line 18) 2694 * Makefile.am, writing: Write Makefile.am. (line 6) 2695 * Makefile.in: Generated Developer Files. 2696 (line 26) 2697 * multilibs: Multilibs. (line 6) 2698 * stamp-h: Build Files Description. 2699 (line 41) 2700 * stamp-h.in: Generated Developer Files. 2701 (line 54) 2702 * system names: Configuration Names. (line 6) 2703 * system types: Configuration Names. (line 6) 2704 * target option: Specifying the Target. 2705 (line 10) 2706 * target system: Host and Target. (line 6) 2707 * triplets: Configuration Names. (line 6) 2708 * undefined macros: FAQ. (line 12) 2709 2710 2711 2712 Tag Table: 2713 Node: Top971 2714 Node: Introduction1499 2715 Node: Goals2581 2716 Node: Tools3305 2717 Node: History4299 2718 Node: Building7297 2719 Node: Getting Started10560 2720 Node: Write configure.in11073 2721 Node: Write Makefile.am18324 2722 Node: Write acconfig.h21501 2723 Node: Generate files23038 2724 Node: Getting Started Example25004 2725 Node: Getting Started Example 125759 2726 Node: Getting Started Example 227680 2727 Node: Getting Started Example 330675 2728 Node: Generate Files in Example33039 2729 Node: Files34129 2730 Node: Developer Files34740 2731 Node: Developer Files Picture35120 2732 Node: Written Developer Files36408 2733 Node: Generated Developer Files38960 2734 Node: Build Files42104 2735 Node: Build Files Picture42765 2736 Node: Build Files Description43529 2737 Node: Support Files45535 2738 Node: Configuration Names48417 2739 Node: Configuration Name Definition48917 2740 Node: Using Configuration Names51240 2741 Node: Cross Compilation Tools53210 2742 Node: Cross Compilation Concepts53901 2743 Node: Host and Target54869 2744 Node: Using the Host Type56370 2745 Node: Specifying the Target57719 2746 Node: Using the Target Type58508 2747 Node: Cross Tools in the Cygnus Tree61939 2748 Node: Host and Target Libraries62996 2749 Node: Target Library Configure Scripts66745 2750 Node: Make Targets in Cygnus Tree69837 2751 Node: Target libiberty71185 2752 Node: Canadian Cross72572 2753 Node: Canadian Cross Example73413 2754 Node: Canadian Cross Concepts74532 2755 Node: Build Cross Host Tools76044 2756 Node: Build and Host Options76996 2757 Node: CCross not in Cygnus Tree78782 2758 Node: CCross in Cygnus Tree79760 2759 Node: Standard Cygnus CCross80181 2760 Node: Cross Cygnus CCross81545 2761 Node: Supporting Canadian Cross84345 2762 Node: CCross in Configure84960 2763 Node: CCross in Make88128 2764 Node: Cygnus Configure89731 2765 Node: Cygnus Configure Basics90566 2766 Node: Cygnus Configure in C++ Libraries95244 2767 Node: Multilibs96251 2768 Node: Multilibs in gcc97296 2769 Node: Multilibs in Target Libraries98374 2770 Node: FAQ102565 2771 Node: Index106665 2772 2773 End Tag Table 2774
