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1Installing the GNU C Library
2****************************
41aa20c2 3
6a3951a0 4Before you do anything else, you should read the FAQ at
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5<https://sourceware.org/glibc/wiki/FAQ>. It answers common questions
6and describes problems you may experience with compilation and
7installation.
41aa20c2 8
00c1176b 9 You will need recent versions of several GNU tools: definitely GCC
fe959e1e 10and GNU Make, and possibly others. *Note Tools for Compilation::,
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11below.
12
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13Configuring and compiling the GNU C Library
14===========================================
00c1176b 15
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16The GNU C Library cannot be compiled in the source directory. You must
17build it in a separate build directory. For example, if you have
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18unpacked the GNU C Library sources in '/src/gnu/glibc-VERSION', create a
19directory '/src/gnu/glibc-build' to put the object files in. This
20allows removing the whole build directory in case an error occurs, which
21is the safest way to get a fresh start and should always be done.
00c1176b 22
a8db092e 23 From your object directory, run the shell script 'configure' located
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24at the top level of the source tree. In the scenario above, you'd type
25
f1e86fca 26 $ ../glibc-VERSION/configure ARGS...
00c1176b 27
3858bf28 28 Please note that even though you're building in a separate build
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29directory, the compilation may need to create or modify files and
30directories in the source directory.
f05f5ca3 31
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32'configure' takes many options, but the only one that is usually
33mandatory is '--prefix'. This option tells 'configure' where you want
34the GNU C Library installed. This defaults to '/usr/local', but the
1f77f049 35normal setting to install as the standard system library is
a8db092e 36'--prefix=/usr' for GNU/Linux systems and '--prefix=' (an empty prefix)
1f77f049 37for GNU/Hurd systems.
00c1176b 38
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39 It may also be useful to pass 'CC=COMPILER' and 'CFLAGS=FLAGS'
40arguments to 'configure'. 'CC' selects the C compiler that will be
41used, and 'CFLAGS' sets optimization options for the compiler. Any
42compiler options required for all compilations, such as options
43selecting an ABI or a processor for which to generate code, should be
44included in 'CC'. Options that may be overridden by the GNU C Library
45build system for particular files, such as for optimization and
46debugging, should go in 'CFLAGS'. The default value of 'CFLAGS' is '-g
47-O2', and the GNU C Library cannot be compiled without optimization, so
48if 'CFLAGS' is specified it must enable optimization. For example:
49
50 $ ../glibc-VERSION/configure CC="gcc -m32" CFLAGS="-O3"
00c1176b 51
bd952512 52 The following list describes all of the available options for
a8db092e 53'configure':
00c1176b 54
a8db092e 55'--prefix=DIRECTORY'
00c1176b 56 Install machine-independent data files in subdirectories of
a8db092e 57 'DIRECTORY'. The default is to install in '/usr/local'.
00c1176b 58
a8db092e 59'--exec-prefix=DIRECTORY'
00c1176b 60 Install the library and other machine-dependent files in
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61 subdirectories of 'DIRECTORY'. The default is to the '--prefix'
62 directory if that option is specified, or '/usr/local' otherwise.
00c1176b 63
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64'--with-headers=DIRECTORY'
65 Look for kernel header files in DIRECTORY, not '/usr/include'. The
66 GNU C Library needs information from the kernel's header files
1f77f049 67 describing the interface to the kernel. The GNU C Library will
a8db092e 68 normally look in '/usr/include' for them, but if you specify this
1f77f049 69 option, it will look in DIRECTORY instead.
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70
71 This option is primarily of use on a system where the headers in
a8db092e 72 '/usr/include' come from an older version of the GNU C Library.
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73 Conflicts can occasionally happen in this case. You can also use
74 this option if you want to compile the GNU C Library with a newer
a8db092e 75 set of kernel headers than the ones found in '/usr/include'.
41aa20c2 76
a8db092e 77'--enable-kernel=VERSION'
90d1d40b 78 This option is currently only useful on GNU/Linux systems. The
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79 VERSION parameter should have the form X.Y.Z and describes the
80 smallest version of the Linux kernel the generated library is
81 expected to support. The higher the VERSION number is, the less
82 compatibility code is added, and the faster the code gets.
83
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84'--with-binutils=DIRECTORY'
85 Use the binutils (assembler and linker) in 'DIRECTORY', not the
6736e93b 86 ones the C compiler would default to. You can use this option if
41aa20c2 87 the default binutils on your system cannot deal with all the
a8db092e 88 constructs in the GNU C Library. In that case, 'configure' will
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89 detect the problem and suppress these constructs, so that the
90 library will still be usable, but functionality may be lost--for
91 example, you can't build a shared libc with old binutils.
41aa20c2 92
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93'--with-nonshared-cflags=CFLAGS'
94 Use additional compiler flags CFLAGS to build the parts of the
95 library which are always statically linked into applications and
96 libraries even with shared linking (that is, the object files
97 contained in 'lib*_nonshared.a' libraries). The build process will
98 automatically use the appropriate flags, but this option can be
99 used to set additional flags required for building applications and
100 libraries, to match local policy. For example, if such a policy
101 requires that all code linked into applications must be built with
102 source fortification,
103 '--with-nonshared-cflags=-Wp,-D_FORTIFY_SOURCE=2' will make sure
104 that the objects in 'libc_nonshared.a' are compiled with this flag
105 (although this will not affect the generated code in this
106 particular case and potentially change debugging information and
107 metadata only).
108
a8db092e 109'--disable-shared'
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110 Don't build shared libraries even if it is possible. Not all
111 systems support shared libraries; you need ELF support and
112 (currently) the GNU linker.
41aa20c2 113
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114'--enable-static-pie'
115 Enable static position independent executable (static PIE) support.
116 Static PIE is similar to static executable, but can be loaded at
117 any address without help from a dynamic linker. All static
118 programs as well as static tests are built as static PIE, except
119 for those marked with no-pie. The resulting glibc can be used with
120 the GCC option, -static-pie, which is available with GCC 8 or
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121 above, to create static PIE. This option also implies that glibc
122 programs and tests are created as dynamic position independent
123 executables (PIE) by default.
9d7a3741 124
e6c69509 125'--enable-cet'
9e38f455 126'--enable-cet=permissive'
e6c69509 127 Enable Intel Control-flow Enforcement Technology (CET) support.
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128 When the GNU C Library is built with '--enable-cet' or
129 '--enable-cet=permissive', the resulting library is protected with
130 indirect branch tracking (IBT) and shadow stack (SHSTK). When CET
131 is enabled, the GNU C Library is compatible with all existing
132 executables and shared libraries. This feature is currently
133 supported on i386, x86_64 and x32 with GCC 8 and binutils 2.29 or
134 later. Note that when CET is enabled, the GNU C Library requires
135 CPUs capable of multi-byte NOPs, like x86-64 processors as well as
136 Intel Pentium Pro or newer. With '--enable-cet', it is an error to
137 dlopen a non CET enabled shared library in CET enabled application.
138 With '--enable-cet=permissive', CET is disabled when dlopening a
139 non CET enabled shared library in CET enabled application.
e6c69509 140
e84bd851 141 NOTE: '--enable-cet' has been tested for i686, x86_64 and x32 on
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142 non-CET processors. '--enable-cet' has been tested for i686,
143 x86_64 and x32 on CET processors.
e84bd851 144
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145'--enable-memory-tagging'
146 Enable memory tagging support if the architecture supports it.
147 When the GNU C Library is built with this option then the resulting
148 library will be able to control the use of tagged memory when
149 hardware support is present by use of the tunable
150 'glibc.mem.tagging'. This includes the generation of tagged memory
151 when using the 'malloc' APIs.
152
153 At present only AArch64 platforms with MTE provide this
154 functionality, although the library will still operate (without
155 memory tagging) on older versions of the architecture.
156
157 The default is to disable support for memory tagging.
158
a8db092e 159'--disable-profile'
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160 Don't build libraries with profiling information. You may want to
161 use this option if you don't plan to do profiling.
41aa20c2 162
a8db092e 163'--enable-static-nss'
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164 Compile static versions of the NSS (Name Service Switch) libraries.
165 This is not recommended because it defeats the purpose of NSS; a
166 program linked statically with the NSS libraries cannot be
167 dynamically reconfigured to use a different name database.
168
a8db092e 169'--enable-hardcoded-path-in-tests'
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170 By default, dynamic tests are linked to run with the installed C
171 library. This option hardcodes the newly built C library path in
172 dynamic tests so that they can be invoked directly.
173
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174'--disable-timezone-tools'
175 By default, timezone related utilities ('zic', 'zdump', and
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176 'tzselect') are installed with the GNU C Library. If you are
177 building these independently (e.g. by using the 'tzcode' package),
178 then this option will allow disabling the install of these.
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179
180 Note that you need to make sure the external tools are kept in sync
181 with the versions that the GNU C Library expects as the data
182 formats may change over time. Consult the 'timezone' subdirectory
183 for more details.
184
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185'--enable-stack-protector'
186'--enable-stack-protector=strong'
187'--enable-stack-protector=all'
188 Compile the C library and all other parts of the glibc package
189 (including the threading and math libraries, NSS modules, and
190 transliteration modules) using the GCC '-fstack-protector',
191 '-fstack-protector-strong' or '-fstack-protector-all' options to
192 detect stack overruns. Only the dynamic linker and a small number
193 of routines called directly from assembler are excluded from this
194 protection.
195
2d6ab5df 196'--enable-bind-now'
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197 Disable lazy binding for installed shared objects and programs.
198 This provides additional security hardening because it enables full
199 RELRO and a read-only global offset table (GOT), at the cost of
200 slightly increased program load times.
2d6ab5df 201
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202'--enable-pt_chown'
203 The file 'pt_chown' is a helper binary for 'grantpt' (*note
204 Pseudo-Terminals: Allocation.) that is installed setuid root to fix
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205 up pseudo-terminal ownership on GNU/Hurd. It is not required on
206 GNU/Linux, and the GNU C Library will not use the installed
207 'pt_chown' program when configured with '--enable-pt_chown'.
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208
209'--disable-werror'
210 By default, the GNU C Library is built with '-Werror'. If you wish
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211 to build without this option (for example, if building with a newer
212 version of GCC than this version of the GNU C Library was tested
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213 with, so new warnings cause the build with '-Werror' to fail), you
214 can configure with '--disable-werror'.
215
21933112 216'--disable-mathvec'
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217 By default for x86_64, the GNU C Library is built with the vector
218 math library. Use this option to disable the vector math library.
21933112 219
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220'--enable-tunables'
221 Tunables support allows additional library parameters to be
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222 customized at runtime. This feature is enabled by default. This
223 option can take the following values:
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224
225 'yes'
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226 This is the default if no option is passed to configure. This
227 enables tunables and selects the default frontend (currently
228 'valstring').
229
230 'no'
231 This option disables tunables.
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232
233 'valstring'
234 This enables tunables and selects the 'valstring' frontend for
235 tunables. This frontend allows users to specify tunables as a
236 colon-separated list in a single environment variable
237 'GLIBC_TUNABLES'.
67e58f39 238
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239'--disable-crypt'
240 Do not install the passphrase-hashing library 'libcrypt' or the
241 header file 'crypt.h'. 'unistd.h' will still declare the function
242 'crypt'. Using this option does not change the set of programs
243 that may need to be linked with '-lcrypt'; it only means that the
244 GNU C Library will not provide that library.
245
246 This option is for hackers and distributions experimenting with
247 independently-maintained implementations of libcrypt. It may
248 become the default in a future release.
249
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250'--disable-experimental-malloc'
251 By default, a per-thread cache is enabled in 'malloc'. While this
252 cache can be disabled on a per-application basis using tunables
253 (set glibc.malloc.tcache_count to zero), this option can be used to
254 remove it from the build completely.
255
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256'--build=BUILD-SYSTEM'
257'--host=HOST-SYSTEM'
258 These options are for cross-compiling. If you specify both options
259 and BUILD-SYSTEM is different from HOST-SYSTEM, 'configure' will
260 prepare to cross-compile the GNU C Library from BUILD-SYSTEM to be
261 used on HOST-SYSTEM. You'll probably need the '--with-headers'
262 option too, and you may have to override CONFIGURE's selection of
263 the compiler and/or binutils.
264
265 If you only specify '--host', 'configure' will prepare for a native
266 compile but use what you specify instead of guessing what your
267 system is. This is most useful to change the CPU submodel. For
268 example, if 'configure' guesses your machine as 'i686-pc-linux-gnu'
269 but you want to compile a library for 586es, give
270 '--host=i586-pc-linux-gnu' or just '--host=i586-linux' and add the
271 appropriate compiler flags ('-mcpu=i586' will do the trick) to
db9881ec 272 'CC'.
1792d4db 273
a8db092e 274 If you specify just '--build', 'configure' will get confused.
41aa20c2 275
a8db092e 276'--with-pkgversion=VERSION'
8b748aed 277 Specify a description, possibly including a build number or build
a8db092e 278 date, of the binaries being built, to be included in '--version'
8b748aed 279 output from programs installed with the GNU C Library. For
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280 example, '--with-pkgversion='FooBar GNU/Linux glibc build 123''.
281 The default value is 'GNU libc'.
8b748aed 282
a8db092e 283'--with-bugurl=URL'
8b748aed 284 Specify the URL that users should visit if they wish to report a
a8db092e 285 bug, to be included in '--help' output from programs installed with
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286 the GNU C Library. The default value refers to the main
287 bug-reporting information for the GNU C Library.
288
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289 To build the library and related programs, type 'make'. This will
290produce a lot of output, some of which may look like errors from 'make'
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291but aren't. Look for error messages from 'make' containing '***'.
292Those indicate that something is seriously wrong.
41aa20c2 293
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294 The compilation process can take a long time, depending on the
295configuration and the speed of your machine. Some complex modules may
296take a very long time to compile, as much as several minutes on slower
297machines. Do not panic if the compiler appears to hang.
00c1176b 298
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299 If you want to run a parallel make, simply pass the '-j' option with
300an appropriate numeric parameter to 'make'. You need a recent GNU
301'make' version, though.
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302
303 To build and run test programs which exercise some of the library
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304facilities, type 'make check'. If it does not complete successfully, do
305not use the built library, and report a bug after verifying that the
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306problem is not already known. *Note Reporting Bugs::, for instructions
307on reporting bugs. Note that some of the tests assume they are not
a8db092e 308being run by 'root'. We recommend you compile and test the GNU C
1f77f049 309Library as an unprivileged user.
41aa20c2 310
8d4b5a8a 311 Before reporting bugs make sure there is no problem with your system.
6736e93b 312The tests (and later installation) use some pre-existing files of the
a8db092e 313system such as '/etc/passwd', '/etc/nsswitch.conf' and others. These
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314files must all contain correct and sensible content.
315
a8db092e 316 Normally, 'make check' will run all the tests before reporting all
d6fe5e58 317problems found and exiting with error status if any problems occurred.
a8db092e 318You can specify 'stop-on-test-failure=y' when running 'make check' to
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319make the test run stop and exit with an error status immediately when a
320failure occurs.
321
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322 To format the 'GNU C Library Reference Manual' for printing, type
323'make dvi'. You need a working TeX installation to do this. The
324distribution builds the on-line formatted version of the manual, as Info
325files, as part of the build process. You can build them manually with
326'make info'.
1792d4db 327
c0389ee4 328 The library has a number of special-purpose configuration parameters
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329which you can find in 'Makeconfig'. These can be overwritten with the
330file 'configparms'. To change them, create a 'configparms' in your
331build directory and add values as appropriate for your system. The file
332is included and parsed by 'make' and has to follow the conventions for
333makefiles.
c0389ee4 334
1f77f049 335 It is easy to configure the GNU C Library for cross-compilation by
a8db092e 336setting a few variables in 'configparms'. Set 'CC' to the
c0389ee4 337cross-compiler for the target you configured the library for; it is
a8db092e 338important to use this same 'CC' value when running 'configure', like
db9881ec 339this: 'configure TARGET CC=TARGET-gcc'. Set 'BUILD_CC' to the compiler
6736e93b 340to use for programs run on the build system as part of compiling the
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341library. You may need to set 'AR' to cross-compiling versions of 'ar'
342if the native tools are not configured to work with object files for the
343target you configured for. When cross-compiling the GNU C Library, it
344may be tested using 'make check
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345test-wrapper="SRCDIR/scripts/cross-test-ssh.sh HOSTNAME"', where SRCDIR
346is the absolute directory name for the main source directory and
347HOSTNAME is the host name of a system that can run the newly built
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348binaries of the GNU C Library. The source and build directories must be
349visible at the same locations on both the build system and HOSTNAME.
c0389ee4 350
a8db092e 351 In general, when testing the GNU C Library, 'test-wrapper' may be set
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352to the name and arguments of any program to run newly built binaries.
353This program must preserve the arguments to the binary being run, its
8540f6d2 354working directory and the standard input, output and error file
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355descriptors. If 'TEST-WRAPPER env' will not work to run a program with
356environment variables set, then 'test-wrapper-env' must be set to a
8540f6d2 357program that runs a newly built program with environment variable
a8db092e 358assignments in effect, those assignments being specified as 'VAR=VALUE'
8540f6d2 359before the name of the program to be run. If multiple assignments to
a8db092e 360the same variable are specified, the last assignment specified must take
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361precedence. Similarly, if 'TEST-WRAPPER env -i' will not work to run a
362program with an environment completely empty of variables except those
363directly assigned, then 'test-wrapper-env-only' must be set; its use has
364the same syntax as 'test-wrapper-env', the only difference in its
365semantics being starting with an empty set of environment variables
366rather than the ambient set.
0eb69512 367
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368Installing the C Library
369========================
41aa20c2 370
80ed68b7 371To install the library and its header files, and the Info files of the
a8db092e 372manual, type 'make install'. This will build things, if necessary,
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373before installing them; however, you should still compile everything
374first. If you are installing the GNU C Library as your primary C
375library, we recommend that you shut the system down to single-user mode
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376first, and reboot afterward. This minimizes the risk of breaking things
377when the library changes out from underneath.
1792d4db 378
a8db092e 379 'make install' will do the entire job of upgrading from a previous
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380installation of the GNU C Library version 2.x. There may sometimes be
381headers left behind from the previous installation, but those are
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382generally harmless. If you want to avoid leaving headers behind you can
383do things in the following order.
c0389ee4 384
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385 You must first build the library ('make'), optionally check it ('make
386check'), switch the include directories and then install ('make
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387install'). The steps must be done in this order. Not moving the
388directory before install will result in an unusable mixture of header
389files from both libraries, but configuring, building, and checking the
390library requires the ability to compile and run programs against the old
a8db092e 391library. The new '/usr/include', after switching the include
02c4bbad 392directories and before installing the library should contain the Linux
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393headers, but nothing else. If you do this, you will need to restore any
394headers from libraries other than the GNU C Library yourself after
1f77f049 395installing the library.
c0389ee4 396
1f77f049 397 You can install the GNU C Library somewhere other than where you
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398configured it to go by setting the 'DESTDIR' GNU standard make variable
399on the command line for 'make install'. The value of this variable is
1f77f049 400prepended to all the paths for installation. This is useful when
a8db092e 401setting up a chroot environment or preparing a binary distribution. The
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402directory should be specified with an absolute file name. Installing
403with the 'prefix' and 'exec_prefix' GNU standard make variables set is
404not supported.
1792d4db 405
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406 The GNU C Library includes a daemon called 'nscd', which you may or
407may not want to run. 'nscd' caches name service lookups; it can
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408dramatically improve performance with NIS+, and may help with DNS as
409well.
1792d4db 410
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411 One auxiliary program, '/usr/libexec/pt_chown', is installed setuid
412'root' if the '--enable-pt_chown' configuration option is used. This
413program is invoked by the 'grantpt' function; it sets the permissions on
414a pseudoterminal so it can be used by the calling process. If you are
415using a Linux kernel with the 'devpts' filesystem enabled and mounted at
416'/dev/pts', you don't need this program.
41aa20c2 417
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418 After installation you should configure the timezone and install
419locales for your system. The time zone configuration ensures that your
420system time matches the time for your current timezone. The locales
421ensure that the display of information on your system matches the
422expectations of your language and geographic region.
423
424 The GNU C Library is able to use two kinds of localization
425information sources, the first is a locale database named
426'locale-archive' which is generally installed as
427'/usr/lib/locale/locale-archive'. The locale archive has the benefit of
428taking up less space and being very fast to load, but only if you plan
429to install sixty or more locales. If you plan to install one or two
430locales you can instead install individual locales into their self-named
431directories e.g. '/usr/lib/locale/en_US.utf8'. For example to install
432the German locale using the character set for UTF-8 with name 'de_DE'
433into the locale archive issue the command 'localedef -i de_DE -f UTF-8
434de_DE', and to install just the one locale issue the command 'localedef
435--no-archive -i de_DE -f UTF-8 de_DE'. To configure all locales that
a8db092e 436are supported by the GNU C Library, you can issue from your build
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437directory the command 'make localedata/install-locales' to install all
438locales into the locale archive or 'make
439localedata/install-locale-files' to install all locales as files in the
440default configured locale installation directory (derived from
441'--prefix' or '--localedir'). To install into an alternative system
442root use 'DESTDIR' e.g. 'make localedata/install-locale-files
443DESTDIR=/opt/glibc', but note that this does not change the configured
444prefix.
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445
446 To configure the locally used timezone, set the 'TZ' environment
447variable. The script 'tzselect' helps you to select the right value.
448As an example, for Germany, 'tzselect' would tell you to use
449'TZ='Europe/Berlin''. For a system wide installation (the given paths
450are for an installation with '--prefix=/usr'), link the timezone file
451which is in '/usr/share/zoneinfo' to the file '/etc/localtime'. For
452Germany, you might execute 'ln -s /usr/share/zoneinfo/Europe/Berlin
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453/etc/localtime'.
454
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455Recommended Tools for Compilation
456=================================
41aa20c2 457
80ed68b7 458We recommend installing the following GNU tools before attempting to
1f77f049 459build the GNU C Library:
41aa20c2 460
f2873d2d 461 * GNU 'make' 4.0 or newer
41aa20c2 462
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463 As of relase time, GNU 'make' 4.2.1 is the newest verified to work
464 to build the GNU C Library.
465
4dcbbc3b 466 * GCC 6.2 or newer
0e7727f7 467
4dcbbc3b 468 GCC 6.2 or higher is required. In general it is recommended to use
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469 the newest version of the compiler that is known to work for
470 building the GNU C Library, as newer compilers usually produce
df5919df 471 better code. As of release time, GCC 9.2.1 is the newest compiler
4863355a 472 verified to work to build the GNU C Library.
91ea72b7 473
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474 For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
475 support for '-mno-gnu-attribute', '-mabi=ieeelongdouble', and
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476 '-mabi=ibmlondouble' is required. Likewise, the compiler must also
477 support passing '-mlong-double-128' with the preceding options. As
478 of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0,
479 see GCC PR94200). These additional features are required for
480 building the GNU C Library with support for IEEE long double.
50545f5a 481
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482 For ARC architecture builds, GCC 8.3 or higher is needed.
483
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484 For s390x architecture builds, GCC 7.1 or higher is needed (See gcc
485 Bug 98269).
486
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487 For multi-arch support it is recommended to use a GCC which has
488 been built with support for GNU indirect functions. This ensures
489 that correct debugging information is generated for functions
490 selected by IFUNC resolvers. This support can either be enabled by
491 configuring GCC with '--enable-gnu-indirect-function', or by
492 enabling it by default by setting 'default_gnu_indirect_function'
493 variable for a particular architecture in the GCC source file
494 'gcc/config.gcc'.
495
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496 You can use whatever compiler you like to compile programs that use
497 the GNU C Library.
41aa20c2 498
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499 Check the FAQ for any special compiler issues on particular
500 platforms.
5713a71e 501
073e8fa7 502 * GNU 'binutils' 2.25 or later
41aa20c2 503
a8db092e 504 You must use GNU 'binutils' (as and ld) to build the GNU C Library.
7a49a7d5 505 No other assembler or linker has the necessary functionality at the
df5919df 506 moment. As of release time, GNU 'binutils' 2.32 is the newest
04cb913d 507 verified to work to build the GNU C Library.
41aa20c2 508
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509 For PowerPC 64-bits little-endian (powerpc64le), 'objcopy' is
510 required to support '--update-section'. This option requires
511 binutils 2.26 or newer.
512
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513 ARC architecture needs 'binutils' 2.32 or higher for TLS related
514 fixes.
515
a8db092e 516 * GNU 'texinfo' 4.7 or later
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517
518 To correctly translate and install the Texinfo documentation you
a8db092e 519 need this version of the 'texinfo' package. Earlier versions do
41aa20c2 520 not understand all the tags used in the document, and the
1792d4db 521 installation mechanism for the info files is not present or works
e7124906 522 differently. As of release time, 'texinfo' 6.6 is the newest
04cb913d 523 verified to work to build the GNU C Library.
41aa20c2 524
a8db092e 525 * GNU 'awk' 3.1.2, or higher
00c1176b 526
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527 'awk' is used in several places to generate files. Some 'gawk'
528 extensions are used, including the 'asorti' function, which was
2c8f75f7 529 introduced in version 3.1.2 of 'gawk'. As of release time, 'gawk'
df5919df 530 version 5.0.1 is the newest verified to work to build the GNU C
2c8f75f7 531 Library.
41aa20c2 532
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533 * GNU 'bison' 2.7 or later
534
535 'bison' is used to generate the 'yacc' parser code in the 'intl'
df5919df 536 subdirectory. As of release time, 'bison' version 3.4.1 is the
93493119 537 newest verified to work to build the GNU C Library.
1faaf703 538
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539 * Perl 5
540
3c1622eb 541 Perl is not required, but if present it is used in some tests and
053c52b1 542 the 'mtrace' program, to build the GNU C Library manual. As of
df5919df 543 release time 'perl' version 5.30.1 is the newest verified to work
053c52b1 544 to build the GNU C Library.
41aa20c2 545
a8db092e 546 * GNU 'sed' 3.02 or newer
c0389ee4 547
a8db092e 548 'Sed' is used in several places to generate files. Most scripts
2c8f75f7 549 work with any version of 'sed'. As of release time, 'sed' version
f650932b 550 4.5 is the newest verified to work to build the GNU C Library.
c0389ee4 551
c6982f7e 552 * Python 3.4 or later
3c1622eb 553
c6982f7e 554 Python is required to build the GNU C Library. As of release time,
e7124906 555 Python 3.7.4 is the newest verified to work for building and
330c9d0d 556 testing the GNU C Library.
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557
558 * PExpect 4.0
559
560 The pretty printer tests drive GDB through test programs and
561 compare its output to the printers'. PExpect is used to capture
562 the output of GDB, and should be compatible with the Python version
563 in your system. As of release time PExpect 4.3 is the newest
564 verified to work to test the pretty printers.
565
566 * GDB 7.8 or later with support for Python 2.7/3.4 or later
567
568 GDB itself needs to be configured with Python support in order to
569 use the pretty printers. Notice that your system having Python
570 available doesn't imply that GDB supports it, nor that your
571 system's Python and GDB's have the same version. As of release
e7124906 572 time GNU 'debugger' 8.3 is the newest verified to work to test the
330c9d0d 573 pretty printers.
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574
575 Unless Python, PExpect and GDB with Python support are present, the
576 printer tests will report themselves as 'UNSUPPORTED'. Notice that
577 some of the printer tests require the GNU C Library to be compiled
578 with debugging symbols.
579
a8db092e 580If you change any of the 'configure.ac' files you will also need
0cc70fcf 581
a8db092e 582 * GNU 'autoconf' 2.69 (exactly)
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583
584and if you change any of the message translation files you will need
585
a8db092e 586 * GNU 'gettext' 0.10.36 or later
41aa20c2 587
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588 As of release time, GNU 'gettext' version 0.19.8.1 is the newest
589 version verified to work to build the GNU C Library.
590
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591You may also need these packages if you upgrade your source tree using
592patches, although we try to avoid this.
593
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594Specific advice for GNU/Linux systems
595=====================================
80ed68b7 596
a7a93d50 597If you are installing the GNU C Library on GNU/Linux systems, you need
5b4ecd3f 598to have the header files from a 3.2 or newer kernel around for
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599reference. (For the ia64 architecture, you need version 3.2.18 or newer
600because this is the first version with support for the 'accept4' system
601call.) These headers must be installed using 'make headers_install';
602the headers present in the kernel source directory are not suitable for
603direct use by the GNU C Library. You do not need to use that kernel,
604just have its headers installed where the GNU C Library can access them,
605referred to here as INSTALL-DIRECTORY. The easiest way to do this is to
606unpack it in a directory such as '/usr/src/linux-VERSION'. In that
607directory, run 'make headers_install
1f77f049 608INSTALL_HDR_PATH=INSTALL-DIRECTORY'. Finally, configure the GNU C
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609Library with the option '--with-headers=INSTALL-DIRECTORY/include'. Use
610the most recent kernel you can get your hands on. (If you are
1f77f049 611cross-compiling the GNU C Library, you need to specify
a8db092e 612'ARCH=ARCHITECTURE' in the 'make headers_install' command, where
1f77f049 613ARCHITECTURE is the architecture name used by the Linux kernel, such as
a8db092e 614'x86' or 'powerpc'.)
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615
616 After installing the GNU C Library, you may need to remove or rename
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617directories such as '/usr/include/linux' and '/usr/include/asm', and
618replace them with copies of directories such as 'linux' and 'asm' from
619'INSTALL-DIRECTORY/include'. All directories present in
620'INSTALL-DIRECTORY/include' should be copied, except that the GNU C
621Library provides its own version of '/usr/include/scsi'; the files
622provided by the kernel should be copied without replacing those provided
623by the GNU C Library. The 'linux', 'asm' and 'asm-generic' directories
624are required to compile programs using the GNU C Library; the other
625directories describe interfaces to the kernel but are not required if
626not compiling programs using those interfaces. You do not need to copy
627kernel headers if you did not specify an alternate kernel header source
628using '--with-headers'.
1f77f049 629
a7a93d50 630 The Filesystem Hierarchy Standard for GNU/Linux systems expects some
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631components of the GNU C Library installation to be in '/lib' and some in
632'/usr/lib'. This is handled automatically if you configure the GNU C
633Library with '--prefix=/usr'. If you set some other prefix or allow it
634to default to '/usr/local', then all the components are installed there.
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636Reporting Bugs
637==============
41aa20c2 638
1f77f049 639There are probably bugs in the GNU C Library. There are certainly
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640errors and omissions in this manual. If you report them, they will get
641fixed. If you don't, no one will ever know about them and they will
642remain unfixed for all eternity, if not longer.
643
bd952512 644 It is a good idea to verify that the problem has not already been
a8db092e 645reported. Bugs are documented in two places: The file 'BUGS' describes
8b748aed 646a number of well known bugs and the central GNU C Library bug tracking
a306c790 647system has a WWW interface at <https://sourceware.org/bugzilla/>. The
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648WWW interface gives you access to open and closed reports. A closed
649report normally includes a patch or a hint on solving the problem.
6736e93b 650
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651 To report a bug, first you must find it. With any luck, this will be
652the hard part. Once you've found a bug, make sure it's really a bug. A
653good way to do this is to see if the GNU C Library behaves the same way
654some other C library does. If so, probably you are wrong and the
655libraries are right (but not necessarily). If not, one of the libraries
656is probably wrong. It might not be the GNU C Library. Many historical
657Unix C libraries permit things that we don't, such as closing a file
658twice.
1792d4db 659
1f77f049 660 If you think you have found some way in which the GNU C Library does
1792d4db 661not conform to the ISO and POSIX standards (*note Standards and
c0389ee4 662Portability::), that is definitely a bug. Report it!
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663
664 Once you're sure you've found a bug, try to narrow it down to the
665smallest test case that reproduces the problem. In the case of a C
666library, you really only need to narrow it down to one library function
667call, if possible. This should not be too difficult.
668
669 The final step when you have a simple test case is to report the bug.
5a82c748 670Do this at <https://www.gnu.org/software/libc/bugs.html>.
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671
672 If you are not sure how a function should behave, and this manual
673doesn't tell you, that's a bug in the manual. Report that too! If the
674function's behavior disagrees with the manual, then either the library
675or the manual has a bug, so report the disagreement. If you find any
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676errors or omissions in this manual, please report them to the bug
677database. If you refer to specific sections of the manual, please
678include the section names for easier identification.