INSTALL

   1 Installing the GNU C Library
   2 ****************************
   3
   4 Before you do anything else, you should read the FAQ at
   5 <https://sourceware.org/glibc/wiki/FAQ>.  It answers common questions
   6 and describes problems you may experience with compilation and
   7 installation.
   8
   9    You will need recent versions of several GNU tools: definitely GCC
  10 and GNU Make, and possibly others.  *Note Tools for Compilation::,
  11 below.
  12
  13 Configuring and compiling the GNU C Library
  14 ===========================================
  15
  16 The GNU C Library cannot be compiled in the source directory.  You must
  17 build it in a separate build directory.  For example, if you have
  18 unpacked the GNU C Library sources in ‘/src/gnu/glibc-VERSION’, create a
  19 directory ‘/src/gnu/glibc-build’ to put the object files in.  This
  20 allows removing the whole build directory in case an error occurs, which
  21 is the safest way to get a fresh start and should always be done.
  22
  23    From your object directory, run the shell script ‘configure’ located
  24 at the top level of the source tree.  In the scenario above, you’d type
  25
  26      $ ../glibc-VERSION/configure ARGS...
  27
  28    Please note that even though you’re building in a separate build
  29 directory, the compilation may need to create or modify files and
  30 directories in the source directory.
  31
  32 ‘configure’ takes many options, but the only one that is usually
  33 mandatory is ‘--prefix’.  This option tells ‘configure’ where you want
  34 the GNU C Library installed.  This defaults to ‘/usr/local’, but the
  35 normal setting to install as the standard system library is
  36 ‘--prefix=/usr’ for GNU/Linux systems and ‘--prefix=’ (an empty prefix)
  37 for GNU/Hurd systems.
  38
  39    It may also be useful to pass ‘CC=COMPILER’ and ‘CFLAGS=FLAGS’
  40 arguments to ‘configure’.  ‘CC’ selects the C compiler that will be
  41 used, and ‘CFLAGS’ sets optimization options for the compiler.  Any
  42 compiler options required for all compilations, such as options
  43 selecting an ABI or a processor for which to generate code, should be
  44 included in ‘CC’.  Options that may be overridden by the GNU C Library
  45 build system for particular files, such as for optimization and
  46 debugging, should go in ‘CFLAGS’.  The default value of ‘CFLAGS’ is ‘-g
  47 -O2’, and the GNU C Library cannot be compiled without optimization, so
  48 if ‘CFLAGS’ is specified it must enable optimization.  For example:
  49
  50      $ ../glibc-VERSION/configure CC="gcc -m32" CFLAGS="-O3"
  51
  52    The following list describes all of the available options for
  53 ‘configure’:
  54
  55 ‘--prefix=DIRECTORY’
  56      Install machine-independent data files in subdirectories of
  57      ‘DIRECTORY’.  The default is to install in ‘/usr/local’.
  58
  59 ‘--exec-prefix=DIRECTORY’
  60      Install the library and other machine-dependent files in
  61      subdirectories of ‘DIRECTORY’.  The default is to the ‘--prefix’
  62      directory if that option is specified, or ‘/usr/local’ otherwise.
  63
  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
  67      describing the interface to the kernel.  The GNU C Library will
  68      normally look in ‘/usr/include’ for them, but if you specify this
  69      option, it will look in DIRECTORY instead.
  70
  71      This option is primarily of use on a system where the headers in
  72      ‘/usr/include’ come from an older version of the GNU C Library.
  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
  75      set of kernel headers than the ones found in ‘/usr/include’.
  76
  77 ‘--enable-kernel=VERSION’
  78      This option is currently only useful on GNU/Linux systems.  The
  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
  84 ‘--with-binutils=DIRECTORY’
  85      Use the binutils (assembler and linker) in ‘DIRECTORY’, not the
  86      ones the C compiler would default to.  You can use this option if
  87      the default binutils on your system cannot deal with all the
  88      constructs in the GNU C Library.  In that case, ‘configure’ will
  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.
  92
  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
 109 ‘--with-rtld-early-cflags=CFLAGS’
 110      Use additional compiler flags CFLAGS to build the early startup
 111      code of the dynamic linker.  These flags can be used to enable
 112      early dynamic linker diagnostics to run on CPUs which are not
 113      compatible with the rest of the GNU C Library, for example, due to
 114      compiler flags which target a later instruction set architecture
 115      (ISA).
 116
 117 ‘--with-timeoutfactor=NUM’
 118      Specify an integer NUM to scale the timeout of test programs.  This
 119      factor can be changed at run time using ‘TIMEOUTFACTOR’ environment
 120      variable.
 121
 122 ‘--disable-shared’
 123      Don’t build shared libraries even if it is possible.  Not all
 124      systems support shared libraries; you need ELF support and
 125      (currently) the GNU linker.
 126
 127 ‘--disable-default-pie’
 128      Don’t build glibc programs and the testsuite as position
 129      independent executables (PIE). By default, glibc programs and tests
 130      are created as position independent executables on targets that
 131      support it.  If the toolchain and architecture support it, static
 132      executables are built as static PIE and the resulting glibc can be
 133      used with the GCC option, -static-pie, which is available with GCC
 134      8 or above, to create static PIE.
 135
 136 ‘--enable-cet’
 137 ‘--enable-cet=permissive’
 138      Enable Intel Control-flow Enforcement Technology (CET) support.
 139      When the GNU C Library is built with ‘--enable-cet’ or
 140      ‘--enable-cet=permissive’, the resulting library is protected with
 141      indirect branch tracking (IBT) and shadow stack (SHSTK).  When CET
 142      is enabled, the GNU C Library is compatible with all existing
 143      executables and shared libraries.  This feature is currently
 144      supported on x86_64 and x32 with GCC 8 and binutils 2.29 or later.
 145      With ‘--enable-cet’, it is an error to dlopen a non CET enabled
 146      shared library in CET enabled application.  With
 147      ‘--enable-cet=permissive’, CET is disabled when dlopening a non CET
 148      enabled shared library in CET enabled application.
 149
 150      NOTE: ‘--enable-cet’ has been tested for x86_64 and x32 on non-CET
 151      and CET processors.
 152
 153 ‘--enable-memory-tagging’
 154      Enable memory tagging support if the architecture supports it.
 155      When the GNU C Library is built with this option then the resulting
 156      library will be able to control the use of tagged memory when
 157      hardware support is present by use of the tunable
 158      ‘glibc.mem.tagging’.  This includes the generation of tagged memory
 159      when using the ‘malloc’ APIs.
 160
 161      At present only AArch64 platforms with MTE provide this
 162      functionality, although the library will still operate (without
 163      memory tagging) on older versions of the architecture.
 164
 165      The default is to disable support for memory tagging.
 166
 167 ‘--disable-profile’
 168      Don’t build libraries with profiling information.  You may want to
 169      use this option if you don’t plan to do profiling.
 170
 171 ‘--enable-static-nss’
 172      Compile static versions of the NSS (Name Service Switch) libraries.
 173      This is not recommended because it defeats the purpose of NSS; a
 174      program linked statically with the NSS libraries cannot be
 175      dynamically reconfigured to use a different name database.
 176
 177 ‘--enable-hardcoded-path-in-tests’
 178      By default, dynamic tests are linked to run with the installed C
 179      library.  This option hardcodes the newly built C library path in
 180      dynamic tests so that they can be invoked directly.
 181
 182 ‘--disable-timezone-tools’
 183      By default, timezone related utilities (‘zic’, ‘zdump’, and
 184      ‘tzselect’) are installed with the GNU C Library.  If you are
 185      building these independently (e.g.  by using the ‘tzcode’ package),
 186      then this option will allow disabling the install of these.
 187
 188      Note that you need to make sure the external tools are kept in sync
 189      with the versions that the GNU C Library expects as the data
 190      formats may change over time.  Consult the ‘timezone’ subdirectory
 191      for more details.
 192
 193 ‘--enable-stack-protector’
 194 ‘--enable-stack-protector=strong’
 195 ‘--enable-stack-protector=all’
 196      Compile the C library and all other parts of the glibc package
 197      (including the threading and math libraries, NSS modules, and
 198      transliteration modules) using the GCC ‘-fstack-protector’,
 199      ‘-fstack-protector-strong’ or ‘-fstack-protector-all’ options to
 200      detect stack overruns.  Only the dynamic linker and a small number
 201      of routines called directly from assembler are excluded from this
 202      protection.
 203
 204 ‘--enable-bind-now’
 205      Disable lazy binding for installed shared objects and programs.
 206      This provides additional security hardening because it enables full
 207      RELRO and a read-only global offset table (GOT), at the cost of
 208      slightly increased program load times.
 209
 210 ‘--enable-pt_chown’
 211      The file ‘pt_chown’ is a helper binary for ‘grantpt’ (*note
 212      Pseudo-Terminals: Allocation.) that is installed setuid root to fix
 213      up pseudo-terminal ownership on GNU/Hurd.  It is not required on
 214      GNU/Linux, and the GNU C Library will not use the installed
 215      ‘pt_chown’ program when configured with ‘--enable-pt_chown’.
 216
 217 ‘--disable-werror’
 218      By default, the GNU C Library is built with ‘-Werror’.  If you wish
 219      to build without this option (for example, if building with a newer
 220      version of GCC than this version of the GNU C Library was tested
 221      with, so new warnings cause the build with ‘-Werror’ to fail), you
 222      can configure with ‘--disable-werror’.
 223
 224 ‘--disable-mathvec’
 225      By default for x86_64, the GNU C Library is built with the vector
 226      math library.  Use this option to disable the vector math library.
 227
 228 ‘--disable-scv’
 229      Disable using ‘scv’ instruction for syscalls.  All syscalls will
 230      use ‘sc’ instead, even if the kernel supports ‘scv’.  PowerPC only.
 231
 232 ‘--build=BUILD-SYSTEM’
 233 ‘--host=HOST-SYSTEM’
 234      These options are for cross-compiling.  If you specify both options
 235      and BUILD-SYSTEM is different from HOST-SYSTEM, ‘configure’ will
 236      prepare to cross-compile the GNU C Library from BUILD-SYSTEM to be
 237      used on HOST-SYSTEM.  You’ll probably need the ‘--with-headers’
 238      option too, and you may have to override CONFIGURE’s selection of
 239      the compiler and/or binutils.
 240
 241      If you only specify ‘--host’, ‘configure’ will prepare for a native
 242      compile but use what you specify instead of guessing what your
 243      system is.  This is most useful to change the CPU submodel.  For
 244      example, if ‘configure’ guesses your machine as ‘i686-pc-linux-gnu’
 245      but you want to compile a library for 586es, give
 246      ‘--host=i586-pc-linux-gnu’ or just ‘--host=i586-linux’ and add the
 247      appropriate compiler flags (‘-mcpu=i586’ will do the trick) to
 248      ‘CC’.
 249
 250      If you specify just ‘--build’, ‘configure’ will get confused.
 251
 252 ‘--with-pkgversion=VERSION’
 253      Specify a description, possibly including a build number or build
 254      date, of the binaries being built, to be included in ‘--version’
 255      output from programs installed with the GNU C Library.  For
 256      example, ‘--with-pkgversion='FooBar GNU/Linux glibc build 123'’.
 257      The default value is ‘GNU libc’.
 258
 259 ‘--with-bugurl=URL’
 260      Specify the URL that users should visit if they wish to report a
 261      bug, to be included in ‘--help’ output from programs installed with
 262      the GNU C Library.  The default value refers to the main
 263      bug-reporting information for the GNU C Library.
 264
 265 ‘--enable-fortify-source’
 266 ‘--enable-fortify-source=LEVEL’
 267      Use -D_FORTIFY_SOURCE=‘LEVEL’ to control hardening in the GNU C
 268      Library.  If not provided, ‘LEVEL’ defaults to highest possible
 269      value supported by the build compiler.
 270
 271      Default is to disable fortification.
 272
 273    To build the library and related programs, type ‘make’.  This will
 274 produce a lot of output, some of which may look like errors from ‘make’
 275 but aren’t.  Look for error messages from ‘make’ containing ‘***’.
 276 Those indicate that something is seriously wrong.
 277
 278    The compilation process can take a long time, depending on the
 279 configuration and the speed of your machine.  Some complex modules may
 280 take a very long time to compile, as much as several minutes on slower
 281 machines.  Do not panic if the compiler appears to hang.
 282
 283    If you want to run a parallel make, simply pass the ‘-j’ option with
 284 an appropriate numeric parameter to ‘make’.  You need a recent GNU
 285 ‘make’ version, though.
 286
 287    To build and run test programs which exercise some of the library
 288 facilities, type ‘make check’.  If it does not complete successfully, do
 289 not use the built library, and report a bug after verifying that the
 290 problem is not already known.  *Note Reporting Bugs::, for instructions
 291 on reporting bugs.  Note that some of the tests assume they are not
 292 being run by ‘root’.  We recommend you compile and test the GNU C
 293 Library as an unprivileged user.
 294
 295    Before reporting bugs make sure there is no problem with your system.
 296 The tests (and later installation) use some pre-existing files of the
 297 system such as ‘/etc/passwd’, ‘/etc/nsswitch.conf’ and others.  These
 298 files must all contain correct and sensible content.
 299
 300    Normally, ‘make check’ will run all the tests before reporting all
 301 problems found and exiting with error status if any problems occurred.
 302 You can specify ‘stop-on-test-failure=y’ when running ‘make check’ to
 303 make the test run stop and exit with an error status immediately when a
 304 failure occurs.
 305
 306    To format the ‘GNU C Library Reference Manual’ for printing, type
 307 ‘make dvi’.  You need a working TeX installation to do this.  The
 308 distribution builds the on-line formatted version of the manual, as Info
 309 files, as part of the build process.  You can build them manually with
 310 ‘make info’.
 311
 312    The library has a number of special-purpose configuration parameters
 313 which you can find in ‘Makeconfig’.  These can be overwritten with the
 314 file ‘configparms’.  To change them, create a ‘configparms’ in your
 315 build directory and add values as appropriate for your system.  The file
 316 is included and parsed by ‘make’ and has to follow the conventions for
 317 makefiles.
 318
 319    It is easy to configure the GNU C Library for cross-compilation by
 320 setting a few variables in ‘configparms’.  Set ‘CC’ to the
 321 cross-compiler for the target you configured the library for; it is
 322 important to use this same ‘CC’ value when running ‘configure’, like
 323 this: ‘configure TARGET CC=TARGET-gcc’.  Set ‘BUILD_CC’ to the compiler
 324 to use for programs run on the build system as part of compiling the
 325 library.  You may need to set ‘AR’ to cross-compiling versions of ‘ar’
 326 if the native tools are not configured to work with object files for the
 327 target you configured for.  When cross-compiling the GNU C Library, it
 328 may be tested using ‘make check
 329 test-wrapper="SRCDIR/scripts/cross-test-ssh.sh HOSTNAME"’, where SRCDIR
 330 is the absolute directory name for the main source directory and
 331 HOSTNAME is the host name of a system that can run the newly built
 332 binaries of the GNU C Library.  The source and build directories must be
 333 visible at the same locations on both the build system and HOSTNAME.
 334 The ‘cross-test-ssh.sh’ script requires ‘flock’ from ‘util-linux’ to
 335 work when GLIBC_TEST_ALLOW_TIME_SETTING environment variable is set.
 336
 337    It is also possible to execute tests, which require setting the date
 338 on the target machine.  Following use cases are supported:
 339    • ‘GLIBC_TEST_ALLOW_TIME_SETTING’ is set in the environment in which
 340      eligible tests are executed and have the privilege to run
 341      ‘clock_settime’.  In this case, nothing prevents those tests from
 342      running in parallel, so the caller shall assure that those tests
 343      are serialized or provide a proper wrapper script for them.
 344
 345    • The ‘cross-test-ssh.sh’ script is used and one passes the
 346      ‘--allow-time-setting’ flag.  In this case, both sets
 347      ‘GLIBC_TEST_ALLOW_TIME_SETTING’ and serialization of test execution
 348      are assured automatically.
 349
 350    In general, when testing the GNU C Library, ‘test-wrapper’ may be set
 351 to the name and arguments of any program to run newly built binaries.
 352 This program must preserve the arguments to the binary being run, its
 353 working directory and the standard input, output and error file
 354 descriptors.  If ‘TEST-WRAPPER env’ will not work to run a program with
 355 environment variables set, then ‘test-wrapper-env’ must be set to a
 356 program that runs a newly built program with environment variable
 357 assignments in effect, those assignments being specified as ‘VAR=VALUE’
 358 before the name of the program to be run.  If multiple assignments to
 359 the same variable are specified, the last assignment specified must take
 360 precedence.  Similarly, if ‘TEST-WRAPPER env -i’ will not work to run a
 361 program with an environment completely empty of variables except those
 362 directly assigned, then ‘test-wrapper-env-only’ must be set; its use has
 363 the same syntax as ‘test-wrapper-env’, the only difference in its
 364 semantics being starting with an empty set of environment variables
 365 rather than the ambient set.
 366
 367    For AArch64 with SVE, when testing the GNU C Library, ‘test-wrapper’
 368 may be set to "SRCDIR/sysdeps/unix/sysv/linux/aarch64/vltest.py
 369 VECTOR-LENGTH" to change Vector Length.
 370
 371 Installing the C Library
 372 ========================
 373
 374 To install the library and its header files, and the Info files of the
 375 manual, type ‘make install’.  This will build things, if necessary,
 376 before installing them; however, you should still compile everything
 377 first.  If you are installing the GNU C Library as your primary C
 378 library, we recommend that you shut the system down to single-user mode
 379 first, and reboot afterward.  This minimizes the risk of breaking things
 380 when the library changes out from underneath.
 381
 382    ‘make install’ will do the entire job of upgrading from a previous
 383 installation of the GNU C Library version 2.x.  There may sometimes be
 384 headers left behind from the previous installation, but those are
 385 generally harmless.  If you want to avoid leaving headers behind you can
 386 do things in the following order.
 387
 388    You must first build the library (‘make’), optionally check it (‘make
 389 check’), switch the include directories and then install (‘make
 390 install’).  The steps must be done in this order.  Not moving the
 391 directory before install will result in an unusable mixture of header
 392 files from both libraries, but configuring, building, and checking the
 393 library requires the ability to compile and run programs against the old
 394 library.  The new ‘/usr/include’, after switching the include
 395 directories and before installing the library should contain the Linux
 396 headers, but nothing else.  If you do this, you will need to restore any
 397 headers from libraries other than the GNU C Library yourself after
 398 installing the library.
 399
 400    You can install the GNU C Library somewhere other than where you
 401 configured it to go by setting the ‘DESTDIR’ GNU standard make variable
 402 on the command line for ‘make install’.  The value of this variable is
 403 prepended to all the paths for installation.  This is useful when
 404 setting up a chroot environment or preparing a binary distribution.  The
 405 directory should be specified with an absolute file name.  Installing
 406 with the ‘prefix’ and ‘exec_prefix’ GNU standard make variables set is
 407 not supported.
 408
 409    The GNU C Library includes a daemon called ‘nscd’, which you may or
 410 may not want to run.  ‘nscd’ caches name service lookups; it can
 411 dramatically improve performance with NIS+, and may help with DNS as
 412 well.
 413
 414    One auxiliary program, ‘/usr/libexec/pt_chown’, is installed setuid
 415 ‘root’ if the ‘--enable-pt_chown’ configuration option is used.  This
 416 program is invoked by the ‘grantpt’ function; it sets the permissions on
 417 a pseudoterminal so it can be used by the calling process.  If you are
 418 using a Linux kernel with the ‘devpts’ filesystem enabled and mounted at
 419 ‘/dev/pts’, you don’t need this program.
 420
 421    After installation you should configure the timezone and install
 422 locales for your system.  The time zone configuration ensures that your
 423 system time matches the time for your current timezone.  The locales
 424 ensure that the display of information on your system matches the
 425 expectations of your language and geographic region.
 426
 427    The GNU C Library is able to use two kinds of localization
 428 information sources, the first is a locale database named
 429 ‘locale-archive’ which is generally installed as
 430 ‘/usr/lib/locale/locale-archive’.  The locale archive has the benefit of
 431 taking up less space and being very fast to load, but only if you plan
 432 to install sixty or more locales.  If you plan to install one or two
 433 locales you can instead install individual locales into their self-named
 434 directories e.g. ‘/usr/lib/locale/en_US.utf8’.  For example to install
 435 the German locale using the character set for UTF-8 with name ‘de_DE’
 436 into the locale archive issue the command ‘localedef -i de_DE -f UTF-8
 437 de_DE’, and to install just the one locale issue the command ‘localedef
 438 --no-archive -i de_DE -f UTF-8 de_DE’.  To configure all locales that
 439 are supported by the GNU C Library, you can issue from your build
 440 directory the command ‘make localedata/install-locales’ to install all
 441 locales into the locale archive or ‘make
 442 localedata/install-locale-files’ to install all locales as files in the
 443 default configured locale installation directory (derived from
 444 ‘--prefix’ or ‘--localedir’).  To install into an alternative system
 445 root use ‘DESTDIR’ e.g. ‘make localedata/install-locale-files
 446 DESTDIR=/opt/glibc’, but note that this does not change the configured
 447 prefix.
 448
 449    To configure the locally used timezone, set the ‘TZ’ environment
 450 variable.  The script ‘tzselect’ helps you to select the right value.
 451 As an example, for Germany, ‘tzselect’ would tell you to use
 452 ‘TZ='Europe/Berlin'’.  For a system wide installation (the given paths
 453 are for an installation with ‘--prefix=/usr’), link the timezone file
 454 which is in ‘/usr/share/zoneinfo’ to the file ‘/etc/localtime’.  For
 455 Germany, you might execute ‘ln -s /usr/share/zoneinfo/Europe/Berlin
 456 /etc/localtime’.
 457
 458 Recommended Tools for Compilation
 459 =================================
 460
 461 We recommend installing the following GNU tools before attempting to
 462 build the GNU C Library:
 463
 464    • GNU ‘make’ 4.0 or newer
 465
 466      As of release time, GNU ‘make’ 4.4 is the newest verified to work
 467      to build the GNU C Library.
 468
 469    • GCC 6.2 or newer
 470
 471      GCC 6.2 or higher is required.  In general it is recommended to use
 472      the newest version of the compiler that is known to work for
 473      building the GNU C Library, as newer compilers usually produce
 474      better code.  As of release time, GCC 13.2 is the newest compiler
 475      verified to work to build the GNU C Library.
 476
 477      For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
 478      support for ‘-mno-gnu-attribute’, ‘-mabi=ieeelongdouble’, and
 479      ‘-mabi=ibmlondouble’ is required.  Likewise, the compiler must also
 480      support passing ‘-mlong-double-128’ with the preceding options.  As
 481      of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0,
 482      see GCC PR94200).  These additional features are required for
 483      building the GNU C Library with support for IEEE long double.
 484
 485      For ARC architecture builds, GCC 8.3 or higher is needed.
 486
 487      For s390x architecture builds, GCC 7.1 or higher is needed (See gcc
 488      Bug 98269).
 489
 490      For AArch64 architecture builds with mathvec enabled, GCC 10 or
 491      higher is needed due to dependency on arm_sve.h.
 492
 493      For multi-arch support it is recommended to use a GCC which has
 494      been built with support for GNU indirect functions.  This ensures
 495      that correct debugging information is generated for functions
 496      selected by IFUNC resolvers.  This support can either be enabled by
 497      configuring GCC with ‘--enable-gnu-indirect-function’, or by
 498      enabling it by default by setting ‘default_gnu_indirect_function’
 499      variable for a particular architecture in the GCC source file
 500      ‘gcc/config.gcc’.
 501
 502      You can use whatever compiler you like to compile programs that use
 503      the GNU C Library.
 504
 505      Check the FAQ for any special compiler issues on particular
 506      platforms.
 507
 508    • GNU ‘binutils’ 2.25 or later
 509
 510      You must use GNU ‘binutils’ (as and ld) to build the GNU C Library.
 511      No other assembler or linker has the necessary functionality at the
 512      moment.  As of release time, GNU ‘binutils’ 2.41 is the newest
 513      verified to work to build the GNU C Library.
 514
 515      For PowerPC 64-bits little-endian (powerpc64le), ‘objcopy’ is
 516      required to support ‘--update-section’.  This option requires
 517      binutils 2.26 or newer.
 518
 519      ARC architecture needs ‘binutils’ 2.32 or higher for TLS related
 520      fixes.
 521
 522    • GNU ‘texinfo’ 4.7 or later
 523
 524      To correctly translate and install the Texinfo documentation you
 525      need this version of the ‘texinfo’ package.  Earlier versions do
 526      not understand all the tags used in the document, and the
 527      installation mechanism for the info files is not present or works
 528      differently.  As of release time, ‘texinfo’ 7.0.3 is the newest
 529      verified to work to build the GNU C Library.
 530
 531    • GNU ‘awk’ 3.1.2, or higher
 532
 533      ‘awk’ is used in several places to generate files.  Some ‘gawk’
 534      extensions are used, including the ‘asorti’ function, which was
 535      introduced in version 3.1.2 of ‘gawk’.  As of release time, ‘gawk’
 536      version 5.2.2 is the newest verified to work to build the GNU C
 537      Library.
 538
 539    • GNU ‘bison’ 2.7 or later
 540
 541      ‘bison’ is used to generate the ‘yacc’ parser code in the ‘intl’
 542      subdirectory.  As of release time, ‘bison’ version 3.8.2 is the
 543      newest verified to work to build the GNU C Library.
 544
 545    • Perl 5
 546
 547      Perl is not required, but if present it is used in some tests and
 548      the ‘mtrace’ program, to build the GNU C Library manual.  As of
 549      release time ‘perl’ version 5.38.0 is the newest verified to work
 550      to build the GNU C Library.
 551
 552    • GNU ‘sed’ 3.02 or newer
 553
 554      ‘Sed’ is used in several places to generate files.  Most scripts
 555      work with any version of ‘sed’.  As of release time, ‘sed’ version
 556      4.9 is the newest verified to work to build the GNU C Library.
 557
 558    • Python 3.4 or later
 559
 560      Python is required to build the GNU C Library.  As of release time,
 561      Python 3.11 is the newest verified to work for building and testing
 562      the GNU C Library.
 563
 564    • PExpect 4.0
 565
 566      The pretty printer tests drive GDB through test programs and
 567      compare its output to the printers’.  PExpect is used to capture
 568      the output of GDB, and should be compatible with the Python version
 569      in your system.  As of release time PExpect 4.8.0 is the newest
 570      verified to work to test the pretty printers.
 571
 572    • The Python ‘abnf’ module.
 573
 574      This module is optional and used to verify some ABNF grammars in
 575      the manual.  Version 2.2.0 has been confirmed to work as expected.
 576      A missing ‘abnf’ module does not reduce the test coverage of the
 577      library itself.
 578
 579    • GDB 7.8 or later with support for Python 2.7/3.4 or later
 580
 581      GDB itself needs to be configured with Python support in order to
 582      use the pretty printers.  Notice that your system having Python
 583      available doesn’t imply that GDB supports it, nor that your
 584      system’s Python and GDB’s have the same version.  As of release
 585      time GNU ‘debugger’ 13.2 is the newest verified to work to test the
 586      pretty printers.
 587
 588      Unless Python, PExpect and GDB with Python support are present, the
 589      printer tests will report themselves as ‘UNSUPPORTED’.  Notice that
 590      some of the printer tests require the GNU C Library to be compiled
 591      with debugging symbols.
 592
 593 If you change any of the ‘configure.ac’ files you will also need
 594
 595    • GNU ‘autoconf’ 2.71 (exactly)
 596
 597 and if you change any of the message translation files you will need
 598
 599    • GNU ‘gettext’ 0.10.36 or later
 600
 601      As of release time, GNU ‘gettext’ version 0.21.1 is the newest
 602      version verified to work to build the GNU C Library.
 603
 604 You may also need these packages if you upgrade your source tree using
 605 patches, although we try to avoid this.
 606
 607 Specific advice for GNU/Linux systems
 608 =====================================
 609
 610 If you are installing the GNU C Library on GNU/Linux systems, you need
 611 to have the header files from a 3.2 or newer kernel around for
 612 reference.  (For the ia64 architecture, you need version 3.2.18 or newer
 613 because this is the first version with support for the ‘accept4’ system
 614 call.)  These headers must be installed using ‘make headers_install’;
 615 the headers present in the kernel source directory are not suitable for
 616 direct use by the GNU C Library.  You do not need to use that kernel,
 617 just have its headers installed where the GNU C Library can access them,
 618 referred to here as INSTALL-DIRECTORY.  The easiest way to do this is to
 619 unpack it in a directory such as ‘/usr/src/linux-VERSION’.  In that
 620 directory, run ‘make headers_install
 621 INSTALL_HDR_PATH=INSTALL-DIRECTORY’.  Finally, configure the GNU C
 622 Library with the option ‘--with-headers=INSTALL-DIRECTORY/include’.  Use
 623 the most recent kernel you can get your hands on.  (If you are
 624 cross-compiling the GNU C Library, you need to specify
 625 ‘ARCH=ARCHITECTURE’ in the ‘make headers_install’ command, where
 626 ARCHITECTURE is the architecture name used by the Linux kernel, such as
 627 ‘x86’ or ‘powerpc’.)
 628
 629    After installing the GNU C Library, you may need to remove or rename
 630 directories such as ‘/usr/include/linux’ and ‘/usr/include/asm’, and
 631 replace them with copies of directories such as ‘linux’ and ‘asm’ from
 632 ‘INSTALL-DIRECTORY/include’.  All directories present in
 633 ‘INSTALL-DIRECTORY/include’ should be copied, except that the GNU C
 634 Library provides its own version of ‘/usr/include/scsi’; the files
 635 provided by the kernel should be copied without replacing those provided
 636 by the GNU C Library.  The ‘linux’, ‘asm’ and ‘asm-generic’ directories
 637 are required to compile programs using the GNU C Library; the other
 638 directories describe interfaces to the kernel but are not required if
 639 not compiling programs using those interfaces.  You do not need to copy
 640 kernel headers if you did not specify an alternate kernel header source
 641 using ‘--with-headers’.
 642
 643    The Filesystem Hierarchy Standard for GNU/Linux systems expects some
 644 components of the GNU C Library installation to be in ‘/lib’ and some in
 645 ‘/usr/lib’.  This is handled automatically if you configure the GNU C
 646 Library with ‘--prefix=/usr’.  If you set some other prefix or allow it
 647 to default to ‘/usr/local’, then all the components are installed there.
 648
 649    As of release time, Linux version 6.1.5 is the newest stable version
 650 verified to work to build the GNU C Library.
 651
 652 Reporting Bugs
 653 ==============
 654
 655 There are probably bugs in the GNU C Library.  There are certainly
 656 errors and omissions in this manual.  If you report them, they will get
 657 fixed.  If you don’t, no one will ever know about them and they will
 658 remain unfixed for all eternity, if not longer.
 659
 660    It is a good idea to verify that the problem has not already been
 661 reported.  Bugs are documented in two places: The file ‘BUGS’ describes
 662 a number of well known bugs and the central GNU C Library bug tracking
 663 system has a WWW interface at <https://sourceware.org/bugzilla/>.  The
 664 WWW interface gives you access to open and closed reports.  A closed
 665 report normally includes a patch or a hint on solving the problem.
 666
 667    To report a bug, first you must find it.  With any luck, this will be
 668 the hard part.  Once you’ve found a bug, make sure it’s really a bug.  A
 669 good way to do this is to see if the GNU C Library behaves the same way
 670 some other C library does.  If so, probably you are wrong and the
 671 libraries are right (but not necessarily).  If not, one of the libraries
 672 is probably wrong.  It might not be the GNU C Library.  Many historical
 673 Unix C libraries permit things that we don’t, such as closing a file
 674 twice.
 675
 676    If you think you have found some way in which the GNU C Library does
 677 not conform to the ISO and POSIX standards (*note Standards and
 678 Portability::), that is definitely a bug.  Report it!
 679
 680    Once you’re sure you’ve found a bug, try to narrow it down to the
 681 smallest test case that reproduces the problem.  In the case of a C
 682 library, you really only need to narrow it down to one library function
 683 call, if possible.  This should not be too difficult.
 684
 685    The final step when you have a simple test case is to report the bug.
 686 Do this at <https://www.gnu.org/software/libc/bugs.html>.
 687
 688    If you are not sure how a function should behave, and this manual
 689 doesn’t tell you, that’s a bug in the manual.  Report that too!  If the
 690 function’s behavior disagrees with the manual, then either the library
 691 or the manual has a bug, so report the disagreement.  If you find any
 692 errors or omissions in this manual, please report them to the bug
 693 database.  If you refer to specific sections of the manual, please
 694 include the section names for easier identification.