1 Installing the GNU C Library
2 ****************************
4 Before you do anything else, you should read the file `FAQ' located at
5 the top level of the source tree. This file answers common questions
6 and describes problems you may experience with compilation and
7 installation. It is updated more frequently than this manual.
9 Features can be added to GNU Libc via "add-on" bundles. These are
10 separate tar files, which you unpack into the top level of the source
11 tree. Then you give `configure' the `--enable-add-ons' option to
12 activate them, and they will be compiled into the library.
14 You will need recent versions of several GNU tools: definitely GCC
15 and GNU Make, and possibly others. *Note Tools for Compilation::,
18 Configuring and compiling GNU Libc
19 ==================================
21 GNU libc cannot be compiled in the source directory. You must build it
22 in a separate build directory. For example, if you have unpacked the
23 glibc sources in `/src/gnu/glibc-VERSION', create a directory
24 `/src/gnu/glibc-build' to put the object files in. This allows
25 removing the whole build directory in case an error occurs, which is
26 the safest way to get a fresh start and should always be done.
28 From your object directory, run the shell script `configure' located
29 at the top level of the source tree. In the scenario above, you'd type
31 $ ../glibc-VERSION/configure ARGS...
33 Please note that even though you're building in a separate build
34 directory, the compilation needs to modify a few files in the source
35 directory, especially some files in the manual subdirectory.
37 `configure' takes many options, but the only one that is usually
38 mandatory is `--prefix'. This option tells `configure' where you want
39 glibc installed. This defaults to `/usr/local', but the normal setting
40 to install as the standard system library is `--prefix=/usr' for
41 GNU/Linux systems and `--prefix=' (an empty prefix) for GNU/Hurd
44 It may also be useful to set the CC and CFLAGS variables in the
45 environment when running `configure'. CC selects the C compiler that
46 will be used, and CFLAGS sets optimization options for the compiler.
48 The following list describes all of the available options for
52 Install machine-independent data files in subdirectories of
53 `DIRECTORY'. The default is to install in `/usr/local'.
55 `--exec-prefix=DIRECTORY'
56 Install the library and other machine-dependent files in
57 subdirectories of `DIRECTORY'. The default is to the `--prefix'
58 directory if that option is specified, or `/usr/local' otherwise.
60 `--with-headers=DIRECTORY'
61 Look for kernel header files in DIRECTORY, not `/usr/include'.
62 Glibc needs information from the kernel's private header files.
63 Glibc will normally look in `/usr/include' for them, but if you
64 specify this option, it will look in DIRECTORY instead.
66 This option is primarily of use on a system where the headers in
67 `/usr/include' come from an older version of glibc. Conflicts can
68 occasionally happen in this case. You can also use this option if
69 you want to compile glibc with a newer set of kernel headers than
70 the ones found in `/usr/include'.
72 `--enable-add-ons[=LIST]'
73 Specify add-on packages to include in the build. If this option is
74 specified with no list, it enables all the add-on packages it
75 finds in the main source directory; this is the default behavior.
76 You may specify an explicit list of add-ons to use in LIST,
77 separated by spaces or commas (if you use spaces, remember to
78 quote them from the shell). Each add-on in LIST can be an
79 absolute directory name or can be a directory name relative to the
80 main source directory, or relative to the build directory (that
81 is, the current working directory). For example,
82 `--enable-add-ons=nptl,../glibc-libidn-VERSION'.
84 `--enable-kernel=VERSION'
85 This option is currently only useful on GNU/Linux systems. The
86 VERSION parameter should have the form X.Y.Z and describes the
87 smallest version of the Linux kernel the generated library is
88 expected to support. The higher the VERSION number is, the less
89 compatibility code is added, and the faster the code gets.
91 `--with-binutils=DIRECTORY'
92 Use the binutils (assembler and linker) in `DIRECTORY', not the
93 ones the C compiler would default to. You can use this option if
94 the default binutils on your system cannot deal with all the
95 constructs in the GNU C library. In that case, `configure' will
96 detect the problem and suppress these constructs, so that the
97 library will still be usable, but functionality may be lost--for
98 example, you can't build a shared libc with old binutils.
101 Use this option if your computer lacks hardware floating-point
102 support and your operating system does not emulate an FPU.
107 Don't build shared libraries even if it is possible. Not all
108 systems support shared libraries; you need ELF support and
109 (currently) the GNU linker.
112 Don't build libraries with profiling information. You may want to
113 use this option if you don't plan to do profiling.
115 `--disable-versioning'
116 Don't compile the shared libraries with symbol version information.
117 Doing this will make the resulting library incompatible with old
118 binaries, so it's not recommended.
120 `--enable-static-nss'
121 Compile static versions of the NSS (Name Service Switch) libraries.
122 This is not recommended because it defeats the purpose of NSS; a
123 program linked statically with the NSS libraries cannot be
124 dynamically reconfigured to use a different name database.
127 By default the C library is built with support for thread-local
128 storage if the used tools support it. By using `--without-tls'
129 this can be prevented though there generally is no reason since it
130 creates compatibility problems.
132 `--build=BUILD-SYSTEM'
134 These options are for cross-compiling. If you specify both
135 options and BUILD-SYSTEM is different from HOST-SYSTEM, `configure'
136 will prepare to cross-compile glibc from BUILD-SYSTEM to be used
137 on HOST-SYSTEM. You'll probably need the `--with-headers' option
138 too, and you may have to override CONFIGURE's selection of the
139 compiler and/or binutils.
141 If you only specify `--host', `configure' will prepare for a
142 native compile but use what you specify instead of guessing what
143 your system is. This is most useful to change the CPU submodel.
144 For example, if `configure' guesses your machine as
145 `i586-pc-linux-gnu' but you want to compile a library for 386es,
146 give `--host=i386-pc-linux-gnu' or just `--host=i386-linux' and add
147 the appropriate compiler flags (`-mcpu=i386' will do the trick) to
150 If you specify just `--build', `configure' will get confused.
152 To build the library and related programs, type `make'. This will
153 produce a lot of output, some of which may look like errors from `make'
154 but isn't. Look for error messages from `make' containing `***'.
155 Those indicate that something is seriously wrong.
157 The compilation process can take a long time, depending on the
158 configuration and the speed of your machine. Some complex modules may
159 take a very long time to compile, as much as several minutes on slower
160 machines. Do not panic if the compiler appears to hang.
162 If you want to run a parallel make, simply pass the `-j' option with
163 an appropriate numeric parameter to `make'. You need a recent GNU
164 `make' version, though.
166 To build and run test programs which exercise some of the library
167 facilities, type `make check'. If it does not complete successfully,
168 do not use the built library, and report a bug after verifying that the
169 problem is not already known. *Note Reporting Bugs::, for instructions
170 on reporting bugs. Note that some of the tests assume they are not
171 being run by `root'. We recommend you compile and test glibc as an
174 Before reporting bugs make sure there is no problem with your system.
175 The tests (and later installation) use some pre-existing files of the
176 system such as `/etc/passwd', `/etc/nsswitch.conf' and others. These
177 files must all contain correct and sensible content.
179 To format the `GNU C Library Reference Manual' for printing, type
180 `make dvi'. You need a working TeX installation to do this. The
181 distribution already includes the on-line formatted version of the
182 manual, as Info files. You can regenerate those with `make info', but
183 it shouldn't be necessary.
185 The library has a number of special-purpose configuration parameters
186 which you can find in `Makeconfig'. These can be overwritten with the
187 file `configparms'. To change them, create a `configparms' in your
188 build directory and add values as appropriate for your system. The
189 file is included and parsed by `make' and has to follow the conventions
192 It is easy to configure the GNU C library for cross-compilation by
193 setting a few variables in `configparms'. Set `CC' to the
194 cross-compiler for the target you configured the library for; it is
195 important to use this same `CC' value when running `configure', like
196 this: `CC=TARGET-gcc configure TARGET'. Set `BUILD_CC' to the compiler
197 to use for programs run on the build system as part of compiling the
198 library. You may need to set `AR' to cross-compiling versions of `ar'
199 if the native tools are not configured to work with object files for
200 the target you configured for.
202 Installing the C Library
203 ========================
205 To install the library and its header files, and the Info files of the
206 manual, type `env LANGUAGE=C LC_ALL=C make install'. This will build
207 things, if necessary, before installing them; however, you should still
208 compile everything first. If you are installing glibc as your primary
209 C library, we recommend that you shut the system down to single-user
210 mode first, and reboot afterward. This minimizes the risk of breaking
211 things when the library changes out from underneath.
213 `make install' will do the entire job of upgrading from a previous
214 installation of glibc 2.x. There may sometimes be headers left behind
215 from the previous installation, but those are generally harmless. If
216 you want to avoid leaving headers behind you can do things in the
219 You must first build the library (`make'), optionally check it
220 (`make check'), switch the include directories and then install (`make
221 install'). The steps must be done in this order. Not moving the
222 directory before install will result in an unusable mixture of header
223 files from both libraries, but configuring, building, and checking the
224 library requires the ability to compile and run programs against the old
225 library. The new `/usr/include', after switching the include
226 directories and before installing the library should contain the Linux
227 headers, but nothing else. If you do this, you will need to restore
228 any headers from non-glibc libraries youself after installing the
231 You can install glibc somewhere other than where you configured it
232 to go by setting the `install_root' variable on the command line for
233 `make install'. The value of this variable is prepended to all the
234 paths for installation. This is useful when setting up a chroot
235 environment or preparing a binary distribution. The directory should be
236 specified with an absolute file name.
238 Glibc includes a daemon called `nscd', which you may or may not want
239 to run. `nscd' caches name service lookups; it can dramatically
240 improve performance with NIS+, and may help with DNS as well.
242 One auxiliary program, `/usr/libexec/pt_chown', is installed setuid
243 `root'. This program is invoked by the `grantpt' function; it sets the
244 permissions on a pseudoterminal so it can be used by the calling
245 process. This means programs like `xterm' and `screen' do not have to
246 be setuid to get a pty. (There may be other reasons why they need
247 privileges.) If you are using a 2.1 or newer Linux kernel with the
248 `devptsfs' or `devfs' filesystems providing pty slaves, you don't need
249 this program; otherwise you do. The source for `pt_chown' is in
250 `login/programs/pt_chown.c'.
252 After installation you might want to configure the timezone and
253 locale installation of your system. The GNU C library comes with a
254 locale database which gets configured with `localedef'. For example, to
255 set up a German locale with name `de_DE', simply issue the command
256 `localedef -i de_DE -f ISO-8859-1 de_DE'. To configure all locales
257 that are supported by glibc, you can issue from your build directory the
258 command `make localedata/install-locales'.
260 To configure the locally used timezone, set the `TZ' environment
261 variable. The script `tzselect' helps you to select the right value.
262 As an example, for Germany, `tzselect' would tell you to use
263 `TZ='Europe/Berlin''. For a system wide installation (the given paths
264 are for an installation with `--prefix=/usr'), link the timezone file
265 which is in `/usr/share/zoneinfo' to the file `/etc/localtime'. For
266 Germany, you might execute `ln -s /usr/share/zoneinfo/Europe/Berlin
269 Recommended Tools for Compilation
270 =================================
272 We recommend installing the following GNU tools before attempting to
273 build the GNU C library:
275 * GNU `make' 3.79 or newer
277 You need the latest version of GNU `make'. Modifying the GNU C
278 Library to work with other `make' programs would be so difficult
279 that we recommend you port GNU `make' instead. *Really.* We
280 recommend GNU `make' version 3.79. All earlier versions have
281 severe bugs or lack features.
283 * GCC 3.4 or newer, GCC 4.1 recommended
285 GCC 3.4 or higher is required; as of this writing, GCC 4.4 is the
286 compiler we advise to use for current versions. On certain
287 machines including `powerpc64', compilers prior to GCC 4.0 have
288 bugs that prevent them compiling the C library code. On other
289 machines, GCC 4.1 is required to build the C library with support
290 for the correct `long double' type format; these include `powerpc'
291 (32 bit), `s390' and `s390x'. For other architectures special
292 compiler-provided headers are needed (like `cpuid.h' on x86) which
293 only come with later compiler versions.
295 You can use whatever compiler you like to compile programs that
296 use GNU libc, but be aware that both GCC 2.7 and 2.8 have bugs in
297 their floating-point support that may be triggered by the math
300 Check the FAQ for any special compiler issues on particular
303 * GNU `binutils' 2.15 or later
305 You must use GNU `binutils' (as and ld) to build the GNU C library.
306 No other assembler or linker has the necessary functionality at the
309 * GNU `texinfo' 3.12f
311 To correctly translate and install the Texinfo documentation you
312 need this version of the `texinfo' package. Earlier versions do
313 not understand all the tags used in the document, and the
314 installation mechanism for the info files is not present or works
317 * GNU `awk' 3.0, or higher
319 `Awk' is used in several places to generate files. `gawk' 3.0 is
324 Perl is not required, but it is used if present to test the
325 installation. We may decide to use it elsewhere in the future.
327 * GNU `sed' 3.02 or newer
329 `Sed' is used in several places to generate files. Most scripts
330 work with any version of `sed'. The known exception is the script
331 `po2test.sed' in the `intl' subdirectory which is used to generate
332 `msgs.h' for the test suite. This script works correctly only
333 with GNU `sed' 3.02. If you like to run the test suite, you
334 should definitely upgrade `sed'.
337 If you change any of the `configure.in' files you will also need
339 * GNU `autoconf' 2.53 or higher
341 and if you change any of the message translation files you will need
343 * GNU `gettext' 0.10.36 or later
345 You may also need these packages if you upgrade your source tree using
346 patches, although we try to avoid this.
348 Specific advice for GNU/Linux systems
349 =====================================
351 If you are installing GNU libc on a GNU/Linux system, you need to have
352 the header files from a 2.2 or newer kernel around for reference. For
353 some architectures, like ia64, sh and hppa, you need at least headers
354 from kernel 2.3.99 (sh and hppa) or 2.4.0 (ia64). You do not need to
355 use that kernel, just have its headers where glibc can access at them.
356 The easiest way to do this is to unpack it in a directory such as
357 `/usr/src/linux-2.2.1'. In that directory, run `make config' and
358 accept all the defaults. Then run `make include/linux/version.h'.
359 Finally, configure glibc with the option
360 `--with-headers=/usr/src/linux-2.2.1/include'. Use the most recent
361 kernel you can get your hands on.
363 An alternate tactic is to unpack the 2.2 kernel and run `make
364 config' as above; then, rename or delete `/usr/include', create a new
365 `/usr/include', and make symbolic links of `/usr/include/linux' and
366 `/usr/include/asm' into the kernel sources. You can then configure
367 glibc with no special options.
369 After installing GNU libc, you may need to remove or rename
370 `/usr/include/linux' and `/usr/include/asm', and replace them with
371 copies of `include/linux' and `include/asm-$ARCHITECTURE' taken from
372 the Linux source package which supplied kernel headers for building the
373 library. ARCHITECTURE will be the machine architecture for which the
374 library was built, such as `i386' or `alpha'. You do not need to do
375 this if you did not specify an alternate kernel header source using
376 `--with-headers'. The intent here is that these directories should be
377 copies of, *not* symlinks to, the kernel headers used to build the
380 Note that `/usr/include/net' and `/usr/include/scsi' should *not* be
381 symlinks into the kernel sources. GNU libc provides its own versions
384 GNU/Linux expects some components of the libc installation to be in
385 `/lib' and some in `/usr/lib'. This is handled automatically if you
386 configure glibc with `--prefix=/usr'. If you set some other prefix or
387 allow it to default to `/usr/local', then all the components are
390 You cannot use `nscd' with 2.0 kernels, due to bugs in the
391 kernel-side thread support. `nscd' happens to hit these bugs
392 particularly hard, but you might have problems with any threaded
398 There are probably bugs in the GNU C library. There are certainly
399 errors and omissions in this manual. If you report them, they will get
400 fixed. If you don't, no one will ever know about them and they will
401 remain unfixed for all eternity, if not longer.
403 It is a good idea to verify that the problem has not already been
404 reported. Bugs are documented in two places: The file `BUGS' describes
405 a number of well known bugs and the bug tracking system has a WWW
406 interface at `http://sources.redhat.com/bugzilla/'. The WWW interface
407 gives you access to open and closed reports. A closed report normally
408 includes a patch or a hint on solving the problem.
410 To report a bug, first you must find it. With any luck, this will
411 be the hard part. Once you've found a bug, make sure it's really a
412 bug. A good way to do this is to see if the GNU C library behaves the
413 same way some other C library does. If so, probably you are wrong and
414 the libraries are right (but not necessarily). If not, one of the
415 libraries is probably wrong. It might not be the GNU library. Many
416 historical Unix C libraries permit things that we don't, such as
417 closing a file twice.
419 If you think you have found some way in which the GNU C library does
420 not conform to the ISO and POSIX standards (*note Standards and
421 Portability::), that is definitely a bug. Report it!
423 Once you're sure you've found a bug, try to narrow it down to the
424 smallest test case that reproduces the problem. In the case of a C
425 library, you really only need to narrow it down to one library function
426 call, if possible. This should not be too difficult.
428 The final step when you have a simple test case is to report the bug.
429 Do this using the WWW interface to the bug database.
431 If you are not sure how a function should behave, and this manual
432 doesn't tell you, that's a bug in the manual. Report that too! If the
433 function's behavior disagrees with the manual, then either the library
434 or the manual has a bug, so report the disagreement. If you find any
435 errors or omissions in this manual, please report them to the bug
436 database. If you refer to specific sections of the manual, please
437 include the section names for easier identification.
projects / platform / upstream / glibc.git / blob