5 @node Installation, Maintenance, Library Summary, Top
8 @c %MENU% How to install the GNU C Library
9 @appendix Installing @theglibc{}
11 Before you do anything else, you should read the FAQ at
12 @url{http://sourceware.org/glibc/wiki/FAQ}. It answers common
13 questions and describes problems you may experience with compilation
16 Features can be added to @theglibc{} via @dfn{add-on} bundles. These are
17 separate tar files, which you unpack into the top level of the source
18 tree. Then you give @code{configure} the @samp{--enable-add-ons} option
19 to activate them, and they will be compiled into the library.
21 You will need recent versions of several GNU tools: definitely GCC and
22 GNU Make, and possibly others. @xref{Tools for Compilation}, below.
26 * Configuring and compiling:: How to compile and test GNU libc.
27 * Running make install:: How to install it once you've got it
29 * Tools for Compilation:: You'll need these first.
30 * Linux:: Specific advice for GNU/Linux systems.
31 * Reporting Bugs:: So they'll get fixed.
35 @node Configuring and compiling
36 @appendixsec Configuring and compiling @theglibc{}
40 @Theglibc{} cannot be compiled in the source directory. You must build
41 it in a separate build directory. For example, if you have unpacked
42 the @glibcadj{} sources in @file{/src/gnu/glibc-@var{version}},
44 @file{/src/gnu/glibc-build} to put the object files in. This allows
45 removing the whole build directory in case an error occurs, which is
46 the safest way to get a fresh start and should always be done.
48 From your object directory, run the shell script @file{configure} located
49 at the top level of the source tree. In the scenario above, you'd type
52 $ ../glibc-@var{version}/configure @var{args@dots{}}
55 Please note that even though you're building in a separate build
56 directory, the compilation may need to create or modify files and
57 directories in the source directory.
60 @code{configure} takes many options, but the only one that is usually
61 mandatory is @samp{--prefix}. This option tells @code{configure}
62 where you want @theglibc{} installed. This defaults to @file{/usr/local},
63 but the normal setting to install as the standard system library is
64 @samp{--prefix=/usr} for @gnulinuxsystems{} and @samp{--prefix=} (an
65 empty prefix) for @gnuhurdsystems{}.
67 It may also be useful to set the @var{CC} and @var{CFLAGS} variables in
68 the environment when running @code{configure}. @var{CC} selects the C
69 compiler that will be used, and @var{CFLAGS} sets optimization options
72 The following list describes all of the available options for
76 @item --prefix=@var{directory}
77 Install machine-independent data files in subdirectories of
78 @file{@var{directory}}. The default is to install in @file{/usr/local}.
80 @item --exec-prefix=@var{directory}
81 Install the library and other machine-dependent files in subdirectories
82 of @file{@var{directory}}. The default is to the @samp{--prefix}
83 directory if that option is specified, or @file{/usr/local} otherwise.
85 @item --with-headers=@var{directory}
86 Look for kernel header files in @var{directory}, not
87 @file{/usr/include}. @Theglibc{} needs information from the kernel's header
88 files describing the interface to the kernel. @Theglibc{} will normally
89 look in @file{/usr/include} for them,
90 but if you specify this option, it will look in @var{DIRECTORY} instead.
92 This option is primarily of use on a system where the headers in
93 @file{/usr/include} come from an older version of @theglibc{}. Conflicts can
94 occasionally happen in this case. You can also use this option if you want to
95 compile @theglibc{} with a newer set of kernel headers than the ones found in
98 @item --enable-add-ons[=@var{list}]
99 Specify add-on packages to include in the build. If this option is
100 specified with no list, it enables all the add-on packages it finds in
101 the main source directory; this is the default behavior. You may
102 specify an explicit list of add-ons to use in @var{list}, separated by
103 spaces or commas (if you use spaces, remember to quote them from the
104 shell). Each add-on in @var{list} can be an absolute directory name
105 or can be a directory name relative to the main source directory, or
106 relative to the build directory (that is, the current working directory).
107 For example, @samp{--enable-add-ons=nptl,../glibc-libidn-@var{version}}.
109 @item --enable-kernel=@var{version}
110 This option is currently only useful on @gnulinuxsystems{}. The
111 @var{version} parameter should have the form X.Y.Z and describes the
112 smallest version of the Linux kernel the generated library is expected
113 to support. The higher the @var{version} number is, the less
114 compatibility code is added, and the faster the code gets.
116 @item --with-binutils=@var{directory}
117 Use the binutils (assembler and linker) in @file{@var{directory}}, not
118 the ones the C compiler would default to. You can use this option if
119 the default binutils on your system cannot deal with all the constructs
120 in @theglibc{}. In that case, @code{configure} will detect the
121 problem and suppress these constructs, so that the library will still be
122 usable, but functionality may be lost---for example, you can't build a
123 shared libc with old binutils.
126 Use this option if your computer lacks hardware floating-point support
127 and your operating system does not emulate an FPU.
129 @c disable static doesn't work currently
130 @c @item --disable-static
131 @c Don't build static libraries. Static libraries aren't that useful these
132 @c days, but we recommend you build them in case you need them.
134 @item --disable-shared
135 Don't build shared libraries even if it is possible. Not all systems
136 support shared libraries; you need ELF support and (currently) the GNU
139 @item --disable-profile
140 Don't build libraries with profiling information. You may want to use
141 this option if you don't plan to do profiling.
143 @item --enable-static-nss
144 Compile static versions of the NSS (Name Service Switch) libraries.
145 This is not recommended because it defeats the purpose of NSS; a program
146 linked statically with the NSS libraries cannot be dynamically
147 reconfigured to use a different name database.
149 @item --enable-hardcoded-path-in-tests
150 By default, dynamic tests are linked to run with the installed C library.
151 This option hardcodes the newly built C library path in dynamic tests
152 so that they can be invoked directly.
154 @item --disable-timezone-tools
155 By default, timezone related utilities (@command{zic}, @command{zdump},
156 and @command{tzselect}) are installed with @theglibc{}. If you are building
157 these independently (e.g. by using the @samp{tzcode} package), then this
158 option will allow disabling the install of these.
160 Note that you need to make sure the external tools are kept in sync with
161 the versions that @theglibc{} expects as the data formats may change over
162 time. Consult the @file{timezone} subdirectory for more details.
164 @item --enable-lock-elision=yes
165 Enable lock elision for pthread mutexes by default.
169 @item --enable-pt_chown
170 The file @file{pt_chown} is a helper binary for @code{grantpt}
171 (@pxref{Allocation, Pseudo-Terminals}) that is installed setuid root to
172 fix up pseudo-terminal ownership. It is not built by default because
173 systems using the Linux kernel are commonly built with the @code{devpts}
174 filesystem enabled and mounted at @file{/dev/pts}, which manages
175 pseudo-terminal ownership automatically. By using
176 @samp{--enable-pt_chown}, you may build @file{pt_chown} and install it
177 setuid and owned by @code{root}. The use of @file{pt_chown} introduces
178 additional security risks to the system and you should enable it only if
179 you understand and accept those risks.
181 @item --disable-werror
182 By default, @theglibc{} is built with @option{-Werror}. If you wish
183 to build without this option (for example, if building with a newer
184 version of GCC than this version of @theglibc{} was tested with, so
185 new warnings cause the build with @option{-Werror} to fail), you can
186 configure with @option{--disable-werror}.
188 @item --disable-mathvec
189 By default for x86_64, @theglibc{} is built with vector math library.
190 Use this option to disable vector math library.
192 @item --build=@var{build-system}
193 @itemx --host=@var{host-system}
194 These options are for cross-compiling. If you specify both options and
195 @var{build-system} is different from @var{host-system}, @code{configure}
196 will prepare to cross-compile @theglibc{} from @var{build-system} to be used
197 on @var{host-system}. You'll probably need the @samp{--with-headers}
198 option too, and you may have to override @var{configure}'s selection of
199 the compiler and/or binutils.
201 If you only specify @samp{--host}, @code{configure} will prepare for a
202 native compile but use what you specify instead of guessing what your
203 system is. This is most useful to change the CPU submodel. For example,
204 if @code{configure} guesses your machine as @code{i686-pc-linux-gnu} but
205 you want to compile a library for 586es, give
206 @samp{--host=i586-pc-linux-gnu} or just @samp{--host=i586-linux} and add
207 the appropriate compiler flags (@samp{-mcpu=i586} will do the trick) to
210 If you specify just @samp{--build}, @code{configure} will get confused.
212 @item --with-pkgversion=@var{version}
213 Specify a description, possibly including a build number or build
214 date, of the binaries being built, to be included in
215 @option{--version} output from programs installed with @theglibc{}.
216 For example, @option{--with-pkgversion='FooBar GNU/Linux glibc build
217 123'}. The default value is @samp{GNU libc}.
219 @item --with-bugurl=@var{url}
220 Specify the URL that users should visit if they wish to report a bug,
221 to be included in @option{--help} output from programs installed with
222 @theglibc{}. The default value refers to the main bug-reporting
223 information for @theglibc{}.
226 To build the library and related programs, type @code{make}. This will
227 produce a lot of output, some of which may look like errors from
228 @code{make} but isn't. Look for error messages from @code{make}
229 containing @samp{***}. Those indicate that something is seriously wrong.
231 The compilation process can take a long time, depending on the
232 configuration and the speed of your machine. Some complex modules may
233 take a very long time to compile, as much as several minutes on slower
234 machines. Do not panic if the compiler appears to hang.
236 If you want to run a parallel make, simply pass the @samp{-j} option
237 with an appropriate numeric parameter to @code{make}. You need a recent
238 GNU @code{make} version, though.
240 To build and run test programs which exercise some of the library
241 facilities, type @code{make check}. If it does not complete
242 successfully, do not use the built library, and report a bug after
243 verifying that the problem is not already known. @xref{Reporting Bugs},
244 for instructions on reporting bugs. Note that some of the tests assume
245 they are not being run by @code{root}. We recommend you compile and
246 test @theglibc{} as an unprivileged user.
248 Before reporting bugs make sure there is no problem with your system.
249 The tests (and later installation) use some pre-existing files of the
250 system such as @file{/etc/passwd}, @file{/etc/nsswitch.conf} and others.
251 These files must all contain correct and sensible content.
253 Normally, @code{make check} will run all the tests before reporting
254 all problems found and exiting with error status if any problems
255 occurred. You can specify @samp{stop-on-test-failure=y} when running
256 @code{make check} to make the test run stop and exit with an error
257 status immediately when a failure occurs.
259 To format the @cite{GNU C Library Reference Manual} for printing, type
260 @w{@code{make dvi}}. You need a working @TeX{} installation to do
261 this. The distribution builds the on-line formatted version of the
262 manual, as Info files, as part of the build process. You can build
263 them manually with @w{@code{make info}}.
265 The library has a number of special-purpose configuration parameters
266 which you can find in @file{Makeconfig}. These can be overwritten with
267 the file @file{configparms}. To change them, create a
268 @file{configparms} in your build directory and add values as appropriate
269 for your system. The file is included and parsed by @code{make} and has
270 to follow the conventions for makefiles.
272 It is easy to configure @theglibc{} for cross-compilation by
273 setting a few variables in @file{configparms}. Set @code{CC} to the
274 cross-compiler for the target you configured the library for; it is
275 important to use this same @code{CC} value when running
276 @code{configure}, like this: @samp{CC=@var{target}-gcc configure
277 @var{target}}. Set @code{BUILD_CC} to the compiler to use for programs
278 run on the build system as part of compiling the library. You may need to
279 set @code{AR} to cross-compiling versions of @code{ar}
280 if the native tools are not configured to work with
281 object files for the target you configured for. When cross-compiling
282 @theglibc{}, it may be tested using @samp{make check
283 test-wrapper="@var{srcdir}/scripts/cross-test-ssh.sh @var{hostname}"},
284 where @var{srcdir} is the absolute directory name for the main source
285 directory and @var{hostname} is the host name of a system that can run
286 the newly built binaries of @theglibc{}. The source and build
287 directories must be visible at the same locations on both the build
288 system and @var{hostname}.
290 In general, when testing @theglibc{}, @samp{test-wrapper} may be set
291 to the name and arguments of any program to run newly built binaries.
292 This program must preserve the arguments to the binary being run, its
293 working directory and the standard input, output and error file
294 descriptors. If @samp{@var{test-wrapper} env} will not work to run a
295 program with environment variables set, then @samp{test-wrapper-env}
296 must be set to a program that runs a newly built program with
297 environment variable assignments in effect, those assignments being
298 specified as @samp{@var{var}=@var{value}} before the name of the
299 program to be run. If multiple assignments to the same variable are
300 specified, the last assignment specified must take precedence.
301 Similarly, if @samp{@var{test-wrapper} env -i} will not work to run a
302 program with an environment completely empty of variables except those
303 directly assigned, then @samp{test-wrapper-env-only} must be set; its
304 use has the same syntax as @samp{test-wrapper-env}, the only
305 difference in its semantics being starting with an empty set of
306 environment variables rather than the ambient set.
309 @node Running make install
310 @appendixsec Installing the C Library
313 To install the library and its header files, and the Info files of the
314 manual, type @code{make install}. This will
315 build things, if necessary, before installing them; however, you should
316 still compile everything first. If you are installing @theglibc{} as your
317 primary C library, we recommend that you shut the system down to
318 single-user mode first, and reboot afterward. This minimizes the risk
319 of breaking things when the library changes out from underneath.
321 @samp{make install} will do the entire job of upgrading from a
322 previous installation of @theglibc{} version 2.x. There may sometimes
324 left behind from the previous installation, but those are generally
325 harmless. If you want to avoid leaving headers behind you can do
326 things in the following order.
328 You must first build the library (@samp{make}), optionally check it
329 (@samp{make check}), switch the include directories and then install
330 (@samp{make install}). The steps must be done in this order. Not moving
331 the directory before install will result in an unusable mixture of header
332 files from both libraries, but configuring, building, and checking the
333 library requires the ability to compile and run programs against the old
334 library. The new @file{/usr/include}, after switching the include
335 directories and before installing the library should contain the Linux
336 headers, but nothing else. If you do this, you will need to restore
337 any headers from libraries other than @theglibc{} yourself after installing the
340 You can install @theglibc{} somewhere other than where you configured
341 it to go by setting the @code{DESTDIR} GNU standard make variable on
342 the command line for @samp{make install}. The value of this variable
343 is prepended to all the paths for installation. This is useful when
344 setting up a chroot environment or preparing a binary distribution.
345 The directory should be specified with an absolute file name. Installing
346 with the @code{prefix} and @code{exec_prefix} GNU standard make variables
347 set is not supported.
349 @Theglibc{} includes a daemon called @code{nscd}, which you
350 may or may not want to run. @code{nscd} caches name service lookups; it
351 can dramatically improve performance with NIS+, and may help with DNS as
354 One auxiliary program, @file{/usr/libexec/pt_chown}, is installed setuid
355 @code{root} if the @samp{--enable-pt_chown} configuration option is used.
356 This program is invoked by the @code{grantpt} function; it sets the
357 permissions on a pseudoterminal so it can be used by the calling process.
358 If you are using a Linux kernel with the @code{devpts} filesystem enabled
359 and mounted at @file{/dev/pts}, you don't need this program.
361 After installation you might want to configure the timezone and locale
362 installation of your system. @Theglibc{} comes with a locale
363 database which gets configured with @code{localedef}. For example, to
364 set up a German locale with name @code{de_DE}, simply issue the command
365 @samp{localedef -i de_DE -f ISO-8859-1 de_DE}. To configure all locales
366 that are supported by @theglibc{}, you can issue from your build directory the
367 command @samp{make localedata/install-locales}.
369 To configure the locally used timezone, set the @code{TZ} environment
370 variable. The script @code{tzselect} helps you to select the right value.
371 As an example, for Germany, @code{tzselect} would tell you to use
372 @samp{TZ='Europe/Berlin'}. For a system wide installation (the given
373 paths are for an installation with @samp{--prefix=/usr}), link the
374 timezone file which is in @file{/usr/share/zoneinfo} to the file
375 @file{/etc/localtime}. For Germany, you might execute @samp{ln -s
376 /usr/share/zoneinfo/Europe/Berlin /etc/localtime}.
378 @node Tools for Compilation
379 @appendixsec Recommended Tools for Compilation
380 @cindex installation tools
381 @cindex tools, for installing library
383 We recommend installing the following GNU tools before attempting to
388 GNU @code{make} 3.79 or newer
390 You need the latest version of GNU @code{make}. Modifying @theglibc{}
391 to work with other @code{make} programs would be so difficult that
392 we recommend you port GNU @code{make} instead. @strong{Really.} We
393 recommend GNU @code{make} version 3.79. All earlier versions have severe
394 bugs or lack features.
399 GCC 4.7 or higher is required. In general it is recommended to use
400 the newest version of the compiler that is known to work for building
401 @theglibc{}, as newer compilers usually produce better code. As of
402 release time, GCC 5.3 is the newest compiler verified to work to build
405 You can use whatever compiler you like to compile programs that use
408 Check the FAQ for any special compiler issues on particular platforms.
411 GNU @code{binutils} 2.22 or later
413 You must use GNU @code{binutils} (as and ld) to build @theglibc{}.
414 No other assembler or linker has the necessary functionality at the
415 moment. As of release time, GNU @code{binutils} 2.25 is the newest
416 verified to work to build @theglibc{}.
419 GNU @code{texinfo} 4.7 or later
421 To correctly translate and install the Texinfo documentation you need
422 this version of the @code{texinfo} package. Earlier versions do not
423 understand all the tags used in the document, and the installation
424 mechanism for the info files is not present or works differently.
425 As of release time, @code{texinfo} 6.0 is the newest verified to work
426 to build @theglibc{}.
429 GNU @code{awk} 3.1.2, or higher
431 @code{awk} is used in several places to generate files.
432 Some @code{gawk} extensions are used, including the @code{asorti}
433 function, which was introduced in version 3.1.2 of @code{gawk}.
434 As of release time, @code{gawk} version 4.1.3 is the newest verified
435 to work to build @theglibc{}.
440 Perl is not required, but it is used if present to test the
441 installation. We may decide to use it elsewhere in the future.
444 GNU @code{sed} 3.02 or newer
446 @code{Sed} is used in several places to generate files. Most scripts work
447 with any version of @code{sed}. As of release time, @code{sed} version
448 4.2.2 is the newest verified to work to build @theglibc{}.
453 If you change any of the @file{configure.ac} files you will also need
457 GNU @code{autoconf} 2.69 (exactly)
461 and if you change any of the message translation files you will need
465 GNU @code{gettext} 0.10.36 or later
469 If you wish to regenerate the @code{yacc} parser code in the @file{intl}
470 subdirectory you will need
474 GNU @code{bison} 2.7 or later
478 You may also need these packages if you upgrade your source tree using
479 patches, although we try to avoid this.
482 @appendixsec Specific advice for @gnulinuxsystems{}
483 @cindex kernel header files
485 If you are installing @theglibc{} on @gnulinuxsystems{}, you need to have
486 the header files from a 3.2 or newer kernel around for reference.
487 These headers must be installed using @samp{make headers_install}; the
488 headers present in the kernel source directory are not suitable for
489 direct use by @theglibc{}. You do not need to use that kernel, just have
490 its headers installed where @theglibc{} can access them, referred to here as
491 @var{install-directory}. The easiest way to do this is to unpack it
492 in a directory such as @file{/usr/src/linux-@var{version}}. In that
493 directory, run @samp{make headers_install
494 INSTALL_HDR_PATH=@var{install-directory}}. Finally, configure @theglibc{}
495 with the option @samp{--with-headers=@var{install-directory}/include}.
496 Use the most recent kernel you can get your hands on. (If you are
497 cross-compiling @theglibc{}, you need to specify
498 @samp{ARCH=@var{architecture}} in the @samp{make headers_install}
499 command, where @var{architecture} is the architecture name used by the
500 Linux kernel, such as @samp{x86} or @samp{powerpc}.)
502 After installing @theglibc{}, you may need to remove or rename
503 directories such as @file{/usr/include/linux} and
504 @file{/usr/include/asm}, and replace them with copies of directories
505 such as @file{linux} and @file{asm} from
506 @file{@var{install-directory}/include}. All directories present in
507 @file{@var{install-directory}/include} should be copied, except that
508 @theglibc{} provides its own version of @file{/usr/include/scsi}; the
509 files provided by the kernel should be copied without replacing those
510 provided by @theglibc{}. The @file{linux}, @file{asm} and
511 @file{asm-generic} directories are required to compile programs using
512 @theglibc{}; the other directories describe interfaces to the kernel but
513 are not required if not compiling programs using those interfaces.
514 You do not need to copy kernel headers if you did not specify an
515 alternate kernel header source using @samp{--with-headers}.
517 The Filesystem Hierarchy Standard for @gnulinuxsystems{} expects some
518 components of the @glibcadj{} installation to be in
519 @file{/lib} and some in @file{/usr/lib}. This is handled automatically
520 if you configure @theglibc{} with @samp{--prefix=/usr}. If you set some other
521 prefix or allow it to default to @file{/usr/local}, then all the
522 components are installed there.
525 @appendixsec Reporting Bugs
526 @cindex reporting bugs
527 @cindex bugs, reporting
529 There are probably bugs in @theglibc{}. There are certainly
530 errors and omissions in this manual. If you report them, they will get
531 fixed. If you don't, no one will ever know about them and they will
532 remain unfixed for all eternity, if not longer.
534 It is a good idea to verify that the problem has not already been
535 reported. Bugs are documented in two places: The file @file{BUGS}
536 describes a number of well known bugs and the central @glibcadj{}
537 bug tracking system has a
539 @url{http://sourceware.org/bugzilla/}. The WWW
540 interface gives you access to open and closed reports. A closed report
541 normally includes a patch or a hint on solving the problem.
543 To report a bug, first you must find it. With any luck, this will be the
544 hard part. Once you've found a bug, make sure it's really a bug. A
545 good way to do this is to see if @theglibc{} behaves the same way
546 some other C library does. If so, probably you are wrong and the
547 libraries are right (but not necessarily). If not, one of the libraries
548 is probably wrong. It might not be @theglibc{}. Many historical
549 Unix C libraries permit things that we don't, such as closing a file
552 If you think you have found some way in which @theglibc{} does not
553 conform to the ISO and POSIX standards (@pxref{Standards and
554 Portability}), that is definitely a bug. Report it!
556 Once you're sure you've found a bug, try to narrow it down to the
557 smallest test case that reproduces the problem. In the case of a C
558 library, you really only need to narrow it down to one library
559 function call, if possible. This should not be too difficult.
561 The final step when you have a simple test case is to report the bug.
562 Do this at @value{REPORT_BUGS_TO}.
564 If you are not sure how a function should behave, and this manual
565 doesn't tell you, that's a bug in the manual. Report that too! If the
566 function's behavior disagrees with the manual, then either the library
567 or the manual has a bug, so report the disagreement. If you find any
568 errors or omissions in this manual, please report them to the
569 bug database. If you refer to specific
570 sections of the manual, please include the section names for easier