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’ is only supported on x86_64 and x32.
 151
 152 ‘--enable-memory-tagging’
 153      Enable memory tagging support if the architecture supports it.
 154      When the GNU C Library is built with this option then the resulting
 155      library will be able to control the use of tagged memory when
 156      hardware support is present by use of the tunable
 157      ‘glibc.mem.tagging’.  This includes the generation of tagged memory
 158      when using the ‘malloc’ APIs.
 159
 160      At present only AArch64 platforms with MTE provide this
 161      functionality, although the library will still operate (without
 162      memory tagging) on older versions of the architecture.
 163
 164      The default is to disable support for memory tagging.
 165
 166 ‘--disable-profile’
 167      Don’t build libraries with profiling information.  You may want to
 168      use this option if you don’t plan to do profiling.
 169
 170 ‘--enable-static-nss’
 171      Compile static versions of the NSS (Name Service Switch) libraries.
 172      This is not recommended because it defeats the purpose of NSS; a
 173      program linked statically with the NSS libraries cannot be
 174      dynamically reconfigured to use a different name database.
 175
 176 ‘--enable-hardcoded-path-in-tests’
 177      By default, dynamic tests are linked to run with the installed C
 178      library.  This option hardcodes the newly built C library path in
 179      dynamic tests so that they can be invoked directly.
 180
 181 ‘--disable-timezone-tools’
 182      By default, timezone related utilities (‘zic’, ‘zdump’, and
 183      ‘tzselect’) are installed with the GNU C Library.  If you are
 184      building these independently (e.g.  by using the ‘tzcode’ package),
 185      then this option will allow disabling the install of these.
 186
 187      Note that you need to make sure the external tools are kept in sync
 188      with the versions that the GNU C Library expects as the data
 189      formats may change over time.  Consult the ‘timezone’ subdirectory
 190      for more details.
 191
 192 ‘--enable-stack-protector’
 193 ‘--enable-stack-protector=strong’
 194 ‘--enable-stack-protector=all’
 195      Compile the C library and all other parts of the glibc package
 196      (including the threading and math libraries, NSS modules, and
 197      transliteration modules) using the GCC ‘-fstack-protector’,
 198      ‘-fstack-protector-strong’ or ‘-fstack-protector-all’ options to
 199      detect stack overruns.  Only the dynamic linker and a small number
 200      of routines called directly from assembler are excluded from this
 201      protection.
 202
 203 ‘--enable-bind-now’
 204      Disable lazy binding for installed shared objects and programs.
 205      This provides additional security hardening because it enables full
 206      RELRO and a read-only global offset table (GOT), at the cost of
 207      slightly increased program load times.
 208
 209 ‘--enable-pt_chown’
 210      The file ‘pt_chown’ is a helper binary for ‘grantpt’ (*note
 211      Pseudo-Terminals: Allocation.) that is installed setuid root to fix
 212      up pseudo-terminal ownership on GNU/Hurd.  It is not required on
 213      GNU/Linux, and the GNU C Library will not use the installed
 214      ‘pt_chown’ program when configured with ‘--enable-pt_chown’.
 215
 216 ‘--disable-werror’
 217      By default, the GNU C Library is built with ‘-Werror’.  If you wish
 218      to build without this option (for example, if building with a newer
 219      version of GCC than this version of the GNU C Library was tested
 220      with, so new warnings cause the build with ‘-Werror’ to fail), you
 221      can configure with ‘--disable-werror’.
 222
 223 ‘--disable-mathvec’
 224      By default for x86_64, the GNU C Library is built with the vector
 225      math library.  Use this option to disable the vector math library.
 226
 227 ‘--disable-scv’
 228      Disable using ‘scv’ instruction for syscalls.  All syscalls will
 229      use ‘sc’ instead, even if the kernel supports ‘scv’.  PowerPC only.
 230
 231 ‘--build=BUILD-SYSTEM’
 232 ‘--host=HOST-SYSTEM’
 233      These options are for cross-compiling.  If you specify both options
 234      and BUILD-SYSTEM is different from HOST-SYSTEM, ‘configure’ will
 235      prepare to cross-compile the GNU C Library from BUILD-SYSTEM to be
 236      used on HOST-SYSTEM.  You’ll probably need the ‘--with-headers’
 237      option too, and you may have to override CONFIGURE’s selection of
 238      the compiler and/or binutils.
 239
 240      If you only specify ‘--host’, ‘configure’ will prepare for a native
 241      compile but use what you specify instead of guessing what your
 242      system is.  This is most useful to change the CPU submodel.  For
 243      example, if ‘configure’ guesses your machine as ‘i686-pc-linux-gnu’
 244      but you want to compile a library for 586es, give
 245      ‘--host=i586-pc-linux-gnu’ or just ‘--host=i586-linux’ and add the
 246      appropriate compiler flags (‘-mcpu=i586’ will do the trick) to
 247      ‘CC’.
 248
 249      If you specify just ‘--build’, ‘configure’ will get confused.
 250
 251 ‘--with-pkgversion=VERSION’
 252      Specify a description, possibly including a build number or build
 253      date, of the binaries being built, to be included in ‘--version’
 254      output from programs installed with the GNU C Library.  For
 255      example, ‘--with-pkgversion='FooBar GNU/Linux glibc build 123'’.
 256      The default value is ‘GNU libc’.
 257
 258 ‘--with-bugurl=URL’
 259      Specify the URL that users should visit if they wish to report a
 260      bug, to be included in ‘--help’ output from programs installed with
 261      the GNU C Library.  The default value refers to the main
 262      bug-reporting information for the GNU C Library.
 263
 264 ‘--enable-fortify-source’
 265 ‘--enable-fortify-source=LEVEL’
 266      Use -D_FORTIFY_SOURCE=‘LEVEL’ to control hardening in the GNU C
 267      Library.  If not provided, ‘LEVEL’ defaults to highest possible
 268      value supported by the build compiler.
 269
 270      Default is to disable fortification.
 271
 272    To build the library and related programs, type ‘make’.  This will
 273 produce a lot of output, some of which may look like errors from ‘make’
 274 but aren’t.  Look for error messages from ‘make’ containing ‘***’.
 275 Those indicate that something is seriously wrong.
 276
 277    The compilation process can take a long time, depending on the
 278 configuration and the speed of your machine.  Some complex modules may
 279 take a very long time to compile, as much as several minutes on slower
 280 machines.  Do not panic if the compiler appears to hang.
 281
 282    If you want to run a parallel make, simply pass the ‘-j’ option with
 283 an appropriate numeric parameter to ‘make’.  You need a recent GNU
 284 ‘make’ version, though.
 285
 286    To build and run test programs which exercise some of the library
 287 facilities, type ‘make check’.  If it does not complete successfully, do
 288 not use the built library, and report a bug after verifying that the
 289 problem is not already known.  *Note Reporting Bugs::, for instructions
 290 on reporting bugs.  Note that some of the tests assume they are not
 291 being run by ‘root’.  We recommend you compile and test the GNU C
 292 Library as an unprivileged user.
 293
 294    Before reporting bugs make sure there is no problem with your system.
 295 The tests (and later installation) use some pre-existing files of the
 296 system such as ‘/etc/passwd’, ‘/etc/nsswitch.conf’ and others.  These
 297 files must all contain correct and sensible content.
 298
 299    Normally, ‘make check’ will run all the tests before reporting all
 300 problems found and exiting with error status if any problems occurred.
 301 You can specify ‘stop-on-test-failure=y’ when running ‘make check’ to
 302 make the test run stop and exit with an error status immediately when a
 303 failure occurs.
 304
 305    To format the ‘GNU C Library Reference Manual’ for printing, type
 306 ‘make dvi’.  You need a working TeX installation to do this.  The
 307 distribution builds the on-line formatted version of the manual, as Info
 308 files, as part of the build process.  You can build them manually with
 309 ‘make info’.
 310
 311    The library has a number of special-purpose configuration parameters
 312 which you can find in ‘Makeconfig’.  These can be overwritten with the
 313 file ‘configparms’.  To change them, create a ‘configparms’ in your
 314 build directory and add values as appropriate for your system.  The file
 315 is included and parsed by ‘make’ and has to follow the conventions for
 316 makefiles.
 317
 318    It is easy to configure the GNU C Library for cross-compilation by
 319 setting a few variables in ‘configparms’.  Set ‘CC’ to the
 320 cross-compiler for the target you configured the library for; it is
 321 important to use this same ‘CC’ value when running ‘configure’, like
 322 this: ‘configure TARGET CC=TARGET-gcc’.  Set ‘BUILD_CC’ to the compiler
 323 to use for programs run on the build system as part of compiling the
 324 library.  You may need to set ‘AR’ to cross-compiling versions of ‘ar’
 325 if the native tools are not configured to work with object files for the
 326 target you configured for.  When cross-compiling the GNU C Library, it
 327 may be tested using ‘make check
 328 test-wrapper="SRCDIR/scripts/cross-test-ssh.sh HOSTNAME"’, where SRCDIR
 329 is the absolute directory name for the main source directory and
 330 HOSTNAME is the host name of a system that can run the newly built
 331 binaries of the GNU C Library.  The source and build directories must be
 332 visible at the same locations on both the build system and HOSTNAME.
 333 The ‘cross-test-ssh.sh’ script requires ‘flock’ from ‘util-linux’ to
 334 work when GLIBC_TEST_ALLOW_TIME_SETTING environment variable is set.
 335
 336    It is also possible to execute tests, which require setting the date
 337 on the target machine.  Following use cases are supported:
 338    • ‘GLIBC_TEST_ALLOW_TIME_SETTING’ is set in the environment in which
 339      eligible tests are executed and have the privilege to run
 340      ‘clock_settime’.  In this case, nothing prevents those tests from
 341      running in parallel, so the caller shall assure that those tests
 342      are serialized or provide a proper wrapper script for them.
 343
 344    • The ‘cross-test-ssh.sh’ script is used and one passes the
 345      ‘--allow-time-setting’ flag.  In this case, both sets
 346      ‘GLIBC_TEST_ALLOW_TIME_SETTING’ and serialization of test execution
 347      are assured automatically.
 348
 349    In general, when testing the GNU C Library, ‘test-wrapper’ may be set
 350 to the name and arguments of any program to run newly built binaries.
 351 This program must preserve the arguments to the binary being run, its
 352 working directory and the standard input, output and error file
 353 descriptors.  If ‘TEST-WRAPPER env’ will not work to run a program with
 354 environment variables set, then ‘test-wrapper-env’ must be set to a
 355 program that runs a newly built program with environment variable
 356 assignments in effect, those assignments being specified as ‘VAR=VALUE’
 357 before the name of the program to be run.  If multiple assignments to
 358 the same variable are specified, the last assignment specified must take
 359 precedence.  Similarly, if ‘TEST-WRAPPER env -i’ will not work to run a
 360 program with an environment completely empty of variables except those
 361 directly assigned, then ‘test-wrapper-env-only’ must be set; its use has
 362 the same syntax as ‘test-wrapper-env’, the only difference in its
 363 semantics being starting with an empty set of environment variables
 364 rather than the ambient set.
 365
 366    For AArch64 with SVE, when testing the GNU C Library, ‘test-wrapper’
 367 may be set to "SRCDIR/sysdeps/unix/sysv/linux/aarch64/vltest.py
 368 VECTOR-LENGTH" to change Vector Length.
 369
 370 Installing the C Library
 371 ========================
 372
 373 To install the library and its header files, and the Info files of the
 374 manual, type ‘make install’.  This will build things, if necessary,
 375 before installing them; however, you should still compile everything
 376 first.  If you are installing the GNU C Library as your primary C
 377 library, we recommend that you shut the system down to single-user mode
 378 first, and reboot afterward.  This minimizes the risk of breaking things
 379 when the library changes out from underneath.
 380
 381    ‘make install’ will do the entire job of upgrading from a previous
 382 installation of the GNU C Library version 2.x.  There may sometimes be
 383 headers left behind from the previous installation, but those are
 384 generally harmless.  If you want to avoid leaving headers behind you can
 385 do things in the following order.
 386
 387    You must first build the library (‘make’), optionally check it (‘make
 388 check’), switch the include directories and then install (‘make
 389 install’).  The steps must be done in this order.  Not moving the
 390 directory before install will result in an unusable mixture of header
 391 files from both libraries, but configuring, building, and checking the
 392 library requires the ability to compile and run programs against the old
 393 library.  The new ‘/usr/include’, after switching the include
 394 directories and before installing the library should contain the Linux
 395 headers, but nothing else.  If you do this, you will need to restore any
 396 headers from libraries other than the GNU C Library yourself after
 397 installing the library.
 398
 399    You can install the GNU C Library somewhere other than where you
 400 configured it to go by setting the ‘DESTDIR’ GNU standard make variable
 401 on the command line for ‘make install’.  The value of this variable is
 402 prepended to all the paths for installation.  This is useful when
 403 setting up a chroot environment or preparing a binary distribution.  The
 404 directory should be specified with an absolute file name.  Installing
 405 with the ‘prefix’ and ‘exec_prefix’ GNU standard make variables set is
 406 not supported.
 407
 408    The GNU C Library includes a daemon called ‘nscd’, which you may or
 409 may not want to run.  ‘nscd’ caches name service lookups; it can
 410 dramatically improve performance with NIS+, and may help with DNS as
 411 well.
 412
 413    One auxiliary program, ‘/usr/libexec/pt_chown’, is installed setuid
 414 ‘root’ if the ‘--enable-pt_chown’ configuration option is used.  This
 415 program is invoked by the ‘grantpt’ function; it sets the permissions on
 416 a pseudoterminal so it can be used by the calling process.  If you are
 417 using a Linux kernel with the ‘devpts’ filesystem enabled and mounted at
 418 ‘/dev/pts’, you don’t need this program.
 419
 420    After installation you should configure the timezone and install
 421 locales for your system.  The time zone configuration ensures that your
 422 system time matches the time for your current timezone.  The locales
 423 ensure that the display of information on your system matches the
 424 expectations of your language and geographic region.
 425
 426    The GNU C Library is able to use two kinds of localization
 427 information sources, the first is a locale database named
 428 ‘locale-archive’ which is generally installed as
 429 ‘/usr/lib/locale/locale-archive’.  The locale archive has the benefit of
 430 taking up less space and being very fast to load, but only if you plan
 431 to install sixty or more locales.  If you plan to install one or two
 432 locales you can instead install individual locales into their self-named
 433 directories e.g. ‘/usr/lib/locale/en_US.utf8’.  For example to install
 434 the German locale using the character set for UTF-8 with name ‘de_DE’
 435 into the locale archive issue the command ‘localedef -i de_DE -f UTF-8
 436 de_DE’, and to install just the one locale issue the command ‘localedef
 437 --no-archive -i de_DE -f UTF-8 de_DE’.  To configure all locales that
 438 are supported by the GNU C Library, you can issue from your build
 439 directory the command ‘make localedata/install-locales’ to install all
 440 locales into the locale archive or ‘make
 441 localedata/install-locale-files’ to install all locales as files in the
 442 default configured locale installation directory (derived from
 443 ‘--prefix’ or ‘--localedir’).  To install into an alternative system
 444 root use ‘DESTDIR’ e.g. ‘make localedata/install-locale-files
 445 DESTDIR=/opt/glibc’, but note that this does not change the configured
 446 prefix.
 447
 448    To configure the locally used timezone, set the ‘TZ’ environment
 449 variable.  The script ‘tzselect’ helps you to select the right value.
 450 As an example, for Germany, ‘tzselect’ would tell you to use
 451 ‘TZ='Europe/Berlin'’.  For a system wide installation (the given paths
 452 are for an installation with ‘--prefix=/usr’), link the timezone file
 453 which is in ‘/usr/share/zoneinfo’ to the file ‘/etc/localtime’.  For
 454 Germany, you might execute ‘ln -s /usr/share/zoneinfo/Europe/Berlin
 455 /etc/localtime’.
 456
 457 Recommended Tools for Compilation
 458 =================================
 459
 460 We recommend installing the following GNU tools before attempting to
 461 build the GNU C Library:
 462
 463    • GNU ‘make’ 4.0 or newer
 464
 465      As of release time, GNU ‘make’ 4.4.1 is the newest verified to work
 466      to build the GNU C Library.
 467
 468    • GCC 6.2 or newer
 469
 470      GCC 6.2 or higher is required.  In general it is recommended to use
 471      the newest version of the compiler that is known to work for
 472      building the GNU C Library, as newer compilers usually produce
 473      better code.  As of release time, GCC 13.2 is the newest compiler
 474      verified to work to build the GNU C Library.
 475
 476      For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
 477      support for ‘-mno-gnu-attribute’, ‘-mabi=ieeelongdouble’, and
 478      ‘-mabi=ibmlondouble’ is required.  Likewise, the compiler must also
 479      support passing ‘-mlong-double-128’ with the preceding options.  As
 480      of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0,
 481      see GCC PR94200).  These additional features are required for
 482      building the GNU C Library with support for IEEE long double.
 483
 484      For ARC architecture builds, GCC 8.3 or higher is needed.
 485
 486      For s390x architecture builds, GCC 7.1 or higher is needed (See gcc
 487      Bug 98269).
 488
 489      For AArch64 architecture builds with mathvec enabled, GCC 10 or
 490      higher is needed due to dependency on arm_sve.h.
 491
 492      For multi-arch support it is recommended to use a GCC which has
 493      been built with support for GNU indirect functions.  This ensures
 494      that correct debugging information is generated for functions
 495      selected by IFUNC resolvers.  This support can either be enabled by
 496      configuring GCC with ‘--enable-gnu-indirect-function’, or by
 497      enabling it by default by setting ‘default_gnu_indirect_function’
 498      variable for a particular architecture in the GCC source file
 499      ‘gcc/config.gcc’.
 500
 501      You can use whatever compiler you like to compile programs that use
 502      the GNU C Library.
 503
 504      Check the FAQ for any special compiler issues on particular
 505      platforms.
 506
 507    • GNU ‘binutils’ 2.25 or later
 508
 509      You must use GNU ‘binutils’ (as and ld) to build the GNU C Library.
 510      No other assembler or linker has the necessary functionality at the
 511      moment.  As of release time, GNU ‘binutils’ 2.42 is the newest
 512      verified to work to build the GNU C Library.
 513
 514      For PowerPC 64-bits little-endian (powerpc64le), ‘objcopy’ is
 515      required to support ‘--update-section’.  This option requires
 516      binutils 2.26 or newer.
 517
 518      ARC architecture needs ‘binutils’ 2.32 or higher for TLS related
 519      fixes.
 520
 521    • GNU ‘texinfo’ 4.7 or later
 522
 523      To correctly translate and install the Texinfo documentation you
 524      need this version of the ‘texinfo’ package.  Earlier versions do
 525      not understand all the tags used in the document, and the
 526      installation mechanism for the info files is not present or works
 527      differently.  As of release time, ‘texinfo’ 7.0.3 is the newest
 528      verified to work to build the GNU C Library.
 529
 530    • GNU ‘awk’ 3.1.2, or higher
 531
 532      ‘awk’ is used in several places to generate files.  Some ‘gawk’
 533      extensions are used, including the ‘asorti’ function, which was
 534      introduced in version 3.1.2 of ‘gawk’.  As of release time, ‘gawk’
 535      version 5.2.2 is the newest verified to work to build the GNU C
 536      Library.
 537
 538    • GNU ‘bison’ 2.7 or later
 539
 540      ‘bison’ is used to generate the ‘yacc’ parser code in the ‘intl’
 541      subdirectory.  As of release time, ‘bison’ version 3.8.2 is the
 542      newest verified to work to build the GNU C Library.
 543
 544    • Perl 5
 545
 546      Perl is not required, but if present it is used in some tests and
 547      the ‘mtrace’ program, to build the GNU C Library manual.  As of
 548      release time ‘perl’ version 5.38.2 is the newest verified to work
 549      to build the GNU C Library.
 550
 551    • GNU ‘sed’ 3.02 or newer
 552
 553      ‘Sed’ is used in several places to generate files.  Most scripts
 554      work with any version of ‘sed’.  As of release time, ‘sed’ version
 555      4.9 is the newest verified to work to build the GNU C Library.
 556
 557    • Python 3.4 or later
 558
 559      Python is required to build the GNU C Library.  As of release time,
 560      Python 3.11 is the newest verified to work for building and testing
 561      the GNU C Library.
 562
 563    • PExpect 4.0
 564
 565      The pretty printer tests drive GDB through test programs and
 566      compare its output to the printers’.  PExpect is used to capture
 567      the output of GDB, and should be compatible with the Python version
 568      in your system.  As of release time PExpect 4.8.0 is the newest
 569      verified to work to test the pretty printers.
 570
 571    • The Python ‘abnf’ module.
 572
 573      This module is optional and used to verify some ABNF grammars in
 574      the manual.  Version 2.2.0 has been confirmed to work as expected.
 575      A missing ‘abnf’ module does not reduce the test coverage of the
 576      library itself.
 577
 578    • GDB 7.8 or later with support for Python 2.7/3.4 or later
 579
 580      GDB itself needs to be configured with Python support in order to
 581      use the pretty printers.  Notice that your system having Python
 582      available doesn’t imply that GDB supports it, nor that your
 583      system’s Python and GDB’s have the same version.  As of release
 584      time GNU ‘debugger’ 13.2 is the newest verified to work to test the
 585      pretty printers.
 586
 587      Unless Python, PExpect and GDB with Python support are present, the
 588      printer tests will report themselves as ‘UNSUPPORTED’.  Notice that
 589      some of the printer tests require the GNU C Library to be compiled
 590      with debugging symbols.
 591
 592 If you change any of the ‘configure.ac’ files you will also need
 593
 594    • GNU ‘autoconf’ 2.71 (exactly)
 595
 596 and if you change any of the message translation files you will need
 597
 598    • GNU ‘gettext’ 0.10.36 or later
 599
 600      As of release time, GNU ‘gettext’ version 0.21.1 is the newest
 601      version verified to work to build the GNU C Library.
 602
 603 You may also need these packages if you upgrade your source tree using
 604 patches, although we try to avoid this.
 605
 606 Specific advice for GNU/Linux systems
 607 =====================================
 608
 609 If you are installing the GNU C Library on GNU/Linux systems, you need
 610 to have the header files from a 3.2 or newer kernel around for
 611 reference.  These headers must be installed using ‘make
 612 headers_install’; the headers present in the kernel source directory are
 613 not suitable for direct use by the GNU C Library.  You do not need to
 614 use that kernel, just have its headers installed where the GNU C Library
 615 can access them, referred to here as INSTALL-DIRECTORY.  The easiest way
 616 to do this is to unpack it in a directory such as
 617 ‘/usr/src/linux-VERSION’.  In that directory, run ‘make headers_install
 618 INSTALL_HDR_PATH=INSTALL-DIRECTORY’.  Finally, configure the GNU C
 619 Library with the option ‘--with-headers=INSTALL-DIRECTORY/include’.  Use
 620 the most recent kernel you can get your hands on.  (If you are
 621 cross-compiling the GNU C Library, you need to specify
 622 ‘ARCH=ARCHITECTURE’ in the ‘make headers_install’ command, where
 623 ARCHITECTURE is the architecture name used by the Linux kernel, such as
 624 ‘x86’ or ‘powerpc’.)
 625
 626    After installing the GNU C Library, you may need to remove or rename
 627 directories such as ‘/usr/include/linux’ and ‘/usr/include/asm’, and
 628 replace them with copies of directories such as ‘linux’ and ‘asm’ from
 629 ‘INSTALL-DIRECTORY/include’.  All directories present in
 630 ‘INSTALL-DIRECTORY/include’ should be copied, except that the GNU C
 631 Library provides its own version of ‘/usr/include/scsi’; the files
 632 provided by the kernel should be copied without replacing those provided
 633 by the GNU C Library.  The ‘linux’, ‘asm’ and ‘asm-generic’ directories
 634 are required to compile programs using the GNU C Library; the other
 635 directories describe interfaces to the kernel but are not required if
 636 not compiling programs using those interfaces.  You do not need to copy
 637 kernel headers if you did not specify an alternate kernel header source
 638 using ‘--with-headers’.
 639
 640    The Filesystem Hierarchy Standard for GNU/Linux systems expects some
 641 components of the GNU C Library installation to be in ‘/lib’ and some in
 642 ‘/usr/lib’.  This is handled automatically if you configure the GNU C
 643 Library with ‘--prefix=/usr’.  If you set some other prefix or allow it
 644 to default to ‘/usr/local’, then all the components are installed there.
 645
 646    As of release time, Linux version 6.1.5 is the newest stable version
 647 verified to work to build the GNU C Library.
 648
 649 Reporting Bugs
 650 ==============
 651
 652 There are probably bugs in the GNU C Library.  There are certainly
 653 errors and omissions in this manual.  If you report them, they will get
 654 fixed.  If you don’t, no one will ever know about them and they will
 655 remain unfixed for all eternity, if not longer.
 656
 657    It is a good idea to verify that the problem has not already been
 658 reported.  Bugs are documented in two places: The file ‘BUGS’ describes
 659 a number of well known bugs and the central GNU C Library bug tracking
 660 system has a WWW interface at <https://sourceware.org/bugzilla/>.  The
 661 WWW interface gives you access to open and closed reports.  A closed
 662 report normally includes a patch or a hint on solving the problem.
 663
 664    To report a bug, first you must find it.  With any luck, this will be
 665 the hard part.  Once you’ve found a bug, make sure it’s really a bug.  A
 666 good way to do this is to see if the GNU C Library behaves the same way
 667 some other C library does.  If so, probably you are wrong and the
 668 libraries are right (but not necessarily).  If not, one of the libraries
 669 is probably wrong.  It might not be the GNU C Library.  Many historical
 670 Unix C libraries permit things that we don’t, such as closing a file
 671 twice.
 672
 673    If you think you have found some way in which the GNU C Library does
 674 not conform to the ISO and POSIX standards (*note Standards and
 675 Portability::), that is definitely a bug.  Report it!
 676
 677    Once you’re sure you’ve found a bug, try to narrow it down to the
 678 smallest test case that reproduces the problem.  In the case of a C
 679 library, you really only need to narrow it down to one library function
 680 call, if possible.  This should not be too difficult.
 681
 682    The final step when you have a simple test case is to report the bug.
 683 Do this at <https://www.gnu.org/software/libc/bugs.html>.
 684
 685    If you are not sure how a function should behave, and this manual
 686 doesn’t tell you, that’s a bug in the manual.  Report that too!  If the
 687 function’s behavior disagrees with the manual, then either the library
 688 or the manual has a bug, so report the disagreement.  If you find any
 689 errors or omissions in this manual, please report them to the bug
 690 database.  If you refer to specific sections of the manual, please
 691 include the section names for easier identification.