INSTALL

   1 Installing the GNU C Library
   2 ****************************
   3
   4 Before you do anything else, you should read the FAQ at
   5 <http://sourceware.org/glibc/wiki/FAQ>.  It answers common questions and
   6 describes problems you may experience with compilation and installation.
   7
   8    Features can be added to the GNU C Library via "add-on" bundles.
   9 These are separate tar files, which you unpack into the top level of the
  10 source tree.  Then you give 'configure' the '--enable-add-ons' option to
  11 activate them, and they will be compiled into the library.
  12
  13    You will need recent versions of several GNU tools: definitely GCC
  14 and GNU Make, and possibly others.  *Note Tools for Compilation::,
  15 below.
  16
  17 Configuring and compiling the GNU C Library
  18 ===========================================
  19
  20 The GNU C Library cannot be compiled in the source directory.  You must
  21 build it in a separate build directory.  For example, if you have
  22 unpacked the GNU C Library sources in '/src/gnu/glibc-VERSION', create a
  23 directory '/src/gnu/glibc-build' to put the object files in.  This
  24 allows removing the whole build directory in case an error occurs, which
  25 is the safest way to get a fresh start and should always be done.
  26
  27    From your object directory, run the shell script 'configure' located
  28 at the top level of the source tree.  In the scenario above, you'd type
  29
  30      $ ../glibc-VERSION/configure ARGS...
  31
  32    Please note that even though you're building in a separate build
  33 directory, the compilation may need to create or modify files and
  34 directories in the source directory.
  35
  36 'configure' takes many options, but the only one that is usually
  37 mandatory is '--prefix'.  This option tells 'configure' where you want
  38 the GNU C Library installed.  This defaults to '/usr/local', but the
  39 normal setting to install as the standard system library is
  40 '--prefix=/usr' for GNU/Linux systems and '--prefix=' (an empty prefix)
  41 for GNU/Hurd systems.
  42
  43    It may also be useful to set the CC and CFLAGS variables in the
  44 environment when running 'configure'.  CC selects the C compiler that
  45 will be used, and CFLAGS sets optimization options for the compiler.
  46
  47    The following list describes all of the available options for
  48 'configure':
  49
  50 '--prefix=DIRECTORY'
  51      Install machine-independent data files in subdirectories of
  52      'DIRECTORY'.  The default is to install in '/usr/local'.
  53
  54 '--exec-prefix=DIRECTORY'
  55      Install the library and other machine-dependent files in
  56      subdirectories of 'DIRECTORY'.  The default is to the '--prefix'
  57      directory if that option is specified, or '/usr/local' otherwise.
  58
  59 '--with-headers=DIRECTORY'
  60      Look for kernel header files in DIRECTORY, not '/usr/include'.  The
  61      GNU C Library needs information from the kernel's header files
  62      describing the interface to the kernel.  The GNU C Library will
  63      normally look in '/usr/include' for them, but if you specify this
  64      option, it will look in DIRECTORY instead.
  65
  66      This option is primarily of use on a system where the headers in
  67      '/usr/include' come from an older version of the GNU C Library.
  68      Conflicts can occasionally happen in this case.  You can also use
  69      this option if you want to compile the GNU C Library with a newer
  70      set of kernel headers than the ones found in '/usr/include'.
  71
  72 '--enable-add-ons[=LIST]'
  73      Specify add-on packages to include in the build.  If this option is
  74      specified with no list, it enables all the add-on packages it finds
  75      in the main source directory; this is the default behavior.  You
  76      may specify an explicit list of add-ons to use in LIST, separated
  77      by spaces or commas (if you use spaces, remember to quote them from
  78      the shell).  Each add-on in LIST can be an absolute directory name
  79      or can be a directory name relative to the main source directory,
  80      or relative to the build directory (that is, the current working
  81      directory).  For example,
  82      '--enable-add-ons=nptl,../glibc-libidn-VERSION'.
  83
  84 '--enable-kernel=VERSION'
  85      This option is currently only useful on GNU/Linux systems.  The
  86      VERSION parameter should have the form X.Y.Z and describes the
  87      smallest version of the Linux kernel the generated library is
  88      expected to support.  The higher the VERSION number is, the less
  89      compatibility code is added, and the faster the code gets.
  90
  91 '--with-binutils=DIRECTORY'
  92      Use the binutils (assembler and linker) in 'DIRECTORY', not the
  93      ones the C compiler would default to.  You can use this option if
  94      the default binutils on your system cannot deal with all the
  95      constructs in the GNU C Library.  In that case, 'configure' will
  96      detect the problem and suppress these constructs, so that the
  97      library will still be usable, but functionality may be lost--for
  98      example, you can't build a shared libc with old binutils.
  99
 100 '--without-fp'
 101      Use this option if your computer lacks hardware floating-point
 102      support and your operating system does not emulate an FPU.
 103
 104 '--disable-shared'
 105      Don't build shared libraries even if it is possible.  Not all
 106      systems support shared libraries; you need ELF support and
 107      (currently) the GNU linker.
 108
 109 '--disable-profile'
 110      Don't build libraries with profiling information.  You may want to
 111      use this option if you don't plan to do profiling.
 112
 113 '--enable-static-nss'
 114      Compile static versions of the NSS (Name Service Switch) libraries.
 115      This is not recommended because it defeats the purpose of NSS; a
 116      program linked statically with the NSS libraries cannot be
 117      dynamically reconfigured to use a different name database.
 118
 119 '--without-tls'
 120      By default the C library is built with support for thread-local
 121      storage if the used tools support it.  By using '--without-tls'
 122      this can be prevented though there generally is no reason since it
 123      creates compatibility problems.
 124
 125 '--enable-hardcoded-path-in-tests'
 126      By default, dynamic tests are linked to run with the installed C
 127      library.  This option hardcodes the newly built C library path in
 128      dynamic tests so that they can be invoked directly.
 129
 130 '--enable-lock-elision=yes'
 131      Enable lock elision for pthread mutexes by default.
 132
 133 '--enable-pt_chown'
 134      The file 'pt_chown' is a helper binary for 'grantpt' (*note
 135      Pseudo-Terminals: Allocation.) that is installed setuid root to fix
 136      up pseudo-terminal ownership.  It is not built by default because
 137      systems using the Linux kernel are commonly built with the 'devpts'
 138      filesystem enabled and mounted at '/dev/pts', which manages
 139      pseudo-terminal ownership automatically.  By using
 140      '--enable-pt_chown', you may build 'pt_chown' and install it setuid
 141      and owned by 'root'.  The use of 'pt_chown' introduces additional
 142      security risks to the system and you should enable it only if you
 143      understand and accept those risks.
 144
 145 '--disable-werror'
 146      By default, the GNU C Library is built with '-Werror'.  If you wish
 147      to build without this option (for example, if building with a newer
 148      version of GCC than this version of the GNU C Library was tested
 149      with, so new warnings cause the build with '-Werror' to fail), you
 150      can configure with '--disable-werror'.
 151
 152 '--disable-mathvec'
 153      By default for x86_64, the GNU C Library is built with vector math
 154      library.  Use this option to disable vector math library.
 155
 156 '--build=BUILD-SYSTEM'
 157 '--host=HOST-SYSTEM'
 158      These options are for cross-compiling.  If you specify both options
 159      and BUILD-SYSTEM is different from HOST-SYSTEM, 'configure' will
 160      prepare to cross-compile the GNU C Library from BUILD-SYSTEM to be
 161      used on HOST-SYSTEM.  You'll probably need the '--with-headers'
 162      option too, and you may have to override CONFIGURE's selection of
 163      the compiler and/or binutils.
 164
 165      If you only specify '--host', 'configure' will prepare for a native
 166      compile but use what you specify instead of guessing what your
 167      system is.  This is most useful to change the CPU submodel.  For
 168      example, if 'configure' guesses your machine as 'i686-pc-linux-gnu'
 169      but you want to compile a library for 586es, give
 170      '--host=i586-pc-linux-gnu' or just '--host=i586-linux' and add the
 171      appropriate compiler flags ('-mcpu=i586' will do the trick) to
 172      CFLAGS.
 173
 174      If you specify just '--build', 'configure' will get confused.
 175
 176 '--with-pkgversion=VERSION'
 177      Specify a description, possibly including a build number or build
 178      date, of the binaries being built, to be included in '--version'
 179      output from programs installed with the GNU C Library.  For
 180      example, '--with-pkgversion='FooBar GNU/Linux glibc build 123''.
 181      The default value is 'GNU libc'.
 182
 183 '--with-bugurl=URL'
 184      Specify the URL that users should visit if they wish to report a
 185      bug, to be included in '--help' output from programs installed with
 186      the GNU C Library.  The default value refers to the main
 187      bug-reporting information for the GNU C Library.
 188
 189    To build the library and related programs, type 'make'.  This will
 190 produce a lot of output, some of which may look like errors from 'make'
 191 but isn't.  Look for error messages from 'make' containing '***'.  Those
 192 indicate that something is seriously wrong.
 193
 194    The compilation process can take a long time, depending on the
 195 configuration and the speed of your machine.  Some complex modules may
 196 take a very long time to compile, as much as several minutes on slower
 197 machines.  Do not panic if the compiler appears to hang.
 198
 199    If you want to run a parallel make, simply pass the '-j' option with
 200 an appropriate numeric parameter to 'make'.  You need a recent GNU
 201 'make' version, though.
 202
 203    To build and run test programs which exercise some of the library
 204 facilities, type 'make check'.  If it does not complete successfully, do
 205 not use the built library, and report a bug after verifying that the
 206 problem is not already known.  *Note Reporting Bugs::, for instructions
 207 on reporting bugs.  Note that some of the tests assume they are not
 208 being run by 'root'.  We recommend you compile and test the GNU C
 209 Library as an unprivileged user.
 210
 211    Before reporting bugs make sure there is no problem with your system.
 212 The tests (and later installation) use some pre-existing files of the
 213 system such as '/etc/passwd', '/etc/nsswitch.conf' and others.  These
 214 files must all contain correct and sensible content.
 215
 216    Normally, 'make check' will run all the tests before reporting all
 217 problems found and exiting with error status if any problems occurred.
 218 You can specify 'stop-on-test-failure=y' when running 'make check' to
 219 make the test run stop and exit with an error status immediately when a
 220 failure occurs.
 221
 222    To format the 'GNU C Library Reference Manual' for printing, type
 223 'make dvi'.  You need a working TeX installation to do this.  The
 224 distribution builds the on-line formatted version of the manual, as Info
 225 files, as part of the build process.  You can build them manually with
 226 'make info'.
 227
 228    The library has a number of special-purpose configuration parameters
 229 which you can find in 'Makeconfig'.  These can be overwritten with the
 230 file 'configparms'.  To change them, create a 'configparms' in your
 231 build directory and add values as appropriate for your system.  The file
 232 is included and parsed by 'make' and has to follow the conventions for
 233 makefiles.
 234
 235    It is easy to configure the GNU C Library for cross-compilation by
 236 setting a few variables in 'configparms'.  Set 'CC' to the
 237 cross-compiler for the target you configured the library for; it is
 238 important to use this same 'CC' value when running 'configure', like
 239 this: 'CC=TARGET-gcc configure TARGET'.  Set 'BUILD_CC' to the compiler
 240 to use for programs run on the build system as part of compiling the
 241 library.  You may need to set 'AR' to cross-compiling versions of 'ar'
 242 if the native tools are not configured to work with object files for the
 243 target you configured for.  When cross-compiling the GNU C Library, it
 244 may be tested using 'make check
 245 test-wrapper="SRCDIR/scripts/cross-test-ssh.sh HOSTNAME"', where SRCDIR
 246 is the absolute directory name for the main source directory and
 247 HOSTNAME is the host name of a system that can run the newly built
 248 binaries of the GNU C Library.  The source and build directories must be
 249 visible at the same locations on both the build system and HOSTNAME.
 250
 251    In general, when testing the GNU C Library, 'test-wrapper' may be set
 252 to the name and arguments of any program to run newly built binaries.
 253 This program must preserve the arguments to the binary being run, its
 254 working directory and the standard input, output and error file
 255 descriptors.  If 'TEST-WRAPPER env' will not work to run a program with
 256 environment variables set, then 'test-wrapper-env' must be set to a
 257 program that runs a newly built program with environment variable
 258 assignments in effect, those assignments being specified as 'VAR=VALUE'
 259 before the name of the program to be run.  If multiple assignments to
 260 the same variable are specified, the last assignment specified must take
 261 precedence.  Similarly, if 'TEST-WRAPPER env -i' will not work to run a
 262 program with an environment completely empty of variables except those
 263 directly assigned, then 'test-wrapper-env-only' must be set; its use has
 264 the same syntax as 'test-wrapper-env', the only difference in its
 265 semantics being starting with an empty set of environment variables
 266 rather than the ambient set.
 267
 268 Installing the C Library
 269 ========================
 270
 271 To install the library and its header files, and the Info files of the
 272 manual, type 'make install'.  This will build things, if necessary,
 273 before installing them; however, you should still compile everything
 274 first.  If you are installing the GNU C Library as your primary C
 275 library, we recommend that you shut the system down to single-user mode
 276 first, and reboot afterward.  This minimizes the risk of breaking things
 277 when the library changes out from underneath.
 278
 279    'make install' will do the entire job of upgrading from a previous
 280 installation of the GNU C Library version 2.x.  There may sometimes be
 281 headers left behind from the previous installation, but those are
 282 generally harmless.  If you want to avoid leaving headers behind you can
 283 do things in the following order.
 284
 285    You must first build the library ('make'), optionally check it ('make
 286 check'), switch the include directories and then install ('make
 287 install').  The steps must be done in this order.  Not moving the
 288 directory before install will result in an unusable mixture of header
 289 files from both libraries, but configuring, building, and checking the
 290 library requires the ability to compile and run programs against the old
 291 library.  The new '/usr/include', after switching the include
 292 directories and before installing the library should contain the Linux
 293 headers, but nothing else.  If you do this, you will need to restore any
 294 headers from libraries other than the GNU C Library yourself after
 295 installing the library.
 296
 297    You can install the GNU C Library somewhere other than where you
 298 configured it to go by setting the 'DESTDIR' GNU standard make variable
 299 on the command line for 'make install'.  The value of this variable is
 300 prepended to all the paths for installation.  This is useful when
 301 setting up a chroot environment or preparing a binary distribution.  The
 302 directory should be specified with an absolute file name.  Installing
 303 with the 'prefix' and 'exec_prefix' GNU standard make variables set is
 304 not supported.
 305
 306    The GNU C Library includes a daemon called 'nscd', which you may or
 307 may not want to run.  'nscd' caches name service lookups; it can
 308 dramatically improve performance with NIS+, and may help with DNS as
 309 well.
 310
 311    One auxiliary program, '/usr/libexec/pt_chown', is installed setuid
 312 'root' if the '--enable-pt_chown' configuration option is used.  This
 313 program is invoked by the 'grantpt' function; it sets the permissions on
 314 a pseudoterminal so it can be used by the calling process.  If you are
 315 using a Linux kernel with the 'devpts' filesystem enabled and mounted at
 316 '/dev/pts', you don't need this program.
 317
 318    After installation you might want to configure the timezone and
 319 locale installation of your system.  The GNU C Library comes with a
 320 locale database which gets configured with 'localedef'.  For example, to
 321 set up a German locale with name 'de_DE', simply issue the command
 322 'localedef -i de_DE -f ISO-8859-1 de_DE'.  To configure all locales that
 323 are supported by the GNU C Library, you can issue from your build
 324 directory the command 'make localedata/install-locales'.
 325
 326    To configure the locally used timezone, set the 'TZ' environment
 327 variable.  The script 'tzselect' helps you to select the right value.
 328 As an example, for Germany, 'tzselect' would tell you to use
 329 'TZ='Europe/Berlin''.  For a system wide installation (the given paths
 330 are for an installation with '--prefix=/usr'), link the timezone file
 331 which is in '/usr/share/zoneinfo' to the file '/etc/localtime'.  For
 332 Germany, you might execute 'ln -s /usr/share/zoneinfo/Europe/Berlin
 333 /etc/localtime'.
 334
 335 Recommended Tools for Compilation
 336 =================================
 337
 338 We recommend installing the following GNU tools before attempting to
 339 build the GNU C Library:
 340
 341    * GNU 'make' 3.79 or newer
 342
 343      You need the latest version of GNU 'make'.  Modifying the GNU C
 344      Library to work with other 'make' programs would be so difficult
 345      that we recommend you port GNU 'make' instead.  *Really.*  We
 346      recommend GNU 'make' version 3.79.  All earlier versions have
 347      severe bugs or lack features.
 348
 349    * GCC 4.6 or newer
 350
 351      GCC 4.6 or higher is required.  In general it is recommended to use
 352      the newest version of the compiler that is known to work for
 353      building the GNU C Library, as newer compilers usually produce
 354      better code.  As of release time, GCC 4.9.2 is the newest compiler
 355      verified to work to build the GNU C Library.
 356
 357      You can use whatever compiler you like to compile programs that use
 358      the GNU C Library.
 359
 360      Check the FAQ for any special compiler issues on particular
 361      platforms.
 362
 363    * GNU 'binutils' 2.22 or later
 364
 365      You must use GNU 'binutils' (as and ld) to build the GNU C Library.
 366      No other assembler or linker has the necessary functionality at the
 367      moment.  As of release time, GNU 'binutils' 2.25 is the newest
 368      verified to work to build the GNU C Library.
 369
 370    * GNU 'texinfo' 4.7 or later
 371
 372      To correctly translate and install the Texinfo documentation you
 373      need this version of the 'texinfo' package.  Earlier versions do
 374      not understand all the tags used in the document, and the
 375      installation mechanism for the info files is not present or works
 376      differently.  As of release time, 'texinfo' 5.2 is the newest
 377      verified to work to build the GNU C Library.
 378
 379    * GNU 'awk' 3.1.2, or higher
 380
 381      'awk' is used in several places to generate files.  Some 'gawk'
 382      extensions are used, including the 'asorti' function, which was
 383      introduced in version 3.1.2 of 'gawk'.
 384
 385    * Perl 5
 386
 387      Perl is not required, but it is used if present to test the
 388      installation.  We may decide to use it elsewhere in the future.
 389
 390    * GNU 'sed' 3.02 or newer
 391
 392      'Sed' is used in several places to generate files.  Most scripts
 393      work with any version of 'sed'.  The known exception is the script
 394      'po2test.sed' in the 'intl' subdirectory which is used to generate
 395      'msgs.h' for the test suite.  This script works correctly only with
 396      GNU 'sed' 3.02.  If you like to run the test suite, you should
 397      definitely upgrade 'sed'.
 398
 399 If you change any of the 'configure.ac' files you will also need
 400
 401    * GNU 'autoconf' 2.69 (exactly)
 402
 403 and if you change any of the message translation files you will need
 404
 405    * GNU 'gettext' 0.10.36 or later
 406
 407 If you wish to regenerate the 'yacc' parser code in the 'intl'
 408 subdirectory you will need
 409
 410    * GNU 'bison' 2.7 or later
 411
 412 You may also need these packages if you upgrade your source tree using
 413 patches, although we try to avoid this.
 414
 415 Specific advice for GNU/Linux systems
 416 =====================================
 417
 418 If you are installing the GNU C Library on GNU/Linux systems, you need
 419 to have the header files from a 2.6.32 or newer kernel around for
 420 reference.  These headers must be installed using 'make
 421 headers_install'; the headers present in the kernel source directory are
 422 not suitable for direct use by the GNU C Library.  You do not need to
 423 use that kernel, just have its headers installed where the GNU C Library
 424 can access them, referred to here as INSTALL-DIRECTORY.  The easiest way
 425 to do this is to unpack it in a directory such as
 426 '/usr/src/linux-VERSION'.  In that directory, run 'make headers_install
 427 INSTALL_HDR_PATH=INSTALL-DIRECTORY'.  Finally, configure the GNU C
 428 Library with the option '--with-headers=INSTALL-DIRECTORY/include'.  Use
 429 the most recent kernel you can get your hands on.  (If you are
 430 cross-compiling the GNU C Library, you need to specify
 431 'ARCH=ARCHITECTURE' in the 'make headers_install' command, where
 432 ARCHITECTURE is the architecture name used by the Linux kernel, such as
 433 'x86' or 'powerpc'.)
 434
 435    After installing the GNU C Library, you may need to remove or rename
 436 directories such as '/usr/include/linux' and '/usr/include/asm', and
 437 replace them with copies of directories such as 'linux' and 'asm' from
 438 'INSTALL-DIRECTORY/include'.  All directories present in
 439 'INSTALL-DIRECTORY/include' should be copied, except that the GNU C
 440 Library provides its own version of '/usr/include/scsi'; the files
 441 provided by the kernel should be copied without replacing those provided
 442 by the GNU C Library.  The 'linux', 'asm' and 'asm-generic' directories
 443 are required to compile programs using the GNU C Library; the other
 444 directories describe interfaces to the kernel but are not required if
 445 not compiling programs using those interfaces.  You do not need to copy
 446 kernel headers if you did not specify an alternate kernel header source
 447 using '--with-headers'.
 448
 449    The Filesystem Hierarchy Standard for GNU/Linux systems expects some
 450 components of the GNU C Library installation to be in '/lib' and some in
 451 '/usr/lib'.  This is handled automatically if you configure the GNU C
 452 Library with '--prefix=/usr'.  If you set some other prefix or allow it
 453 to default to '/usr/local', then all the components are installed there.
 454
 455 Reporting Bugs
 456 ==============
 457
 458 There are probably bugs in the GNU C Library.  There are certainly
 459 errors and omissions in this manual.  If you report them, they will get
 460 fixed.  If you don't, no one will ever know about them and they will
 461 remain unfixed for all eternity, if not longer.
 462
 463    It is a good idea to verify that the problem has not already been
 464 reported.  Bugs are documented in two places: The file 'BUGS' describes
 465 a number of well known bugs and the central GNU C Library bug tracking
 466 system has a WWW interface at <http://sourceware.org/bugzilla/>.  The
 467 WWW interface gives you access to open and closed reports.  A closed
 468 report normally includes a patch or a hint on solving the problem.
 469
 470    To report a bug, first you must find it.  With any luck, this will be
 471 the hard part.  Once you've found a bug, make sure it's really a bug.  A
 472 good way to do this is to see if the GNU C Library behaves the same way
 473 some other C library does.  If so, probably you are wrong and the
 474 libraries are right (but not necessarily).  If not, one of the libraries
 475 is probably wrong.  It might not be the GNU C Library.  Many historical
 476 Unix C libraries permit things that we don't, such as closing a file
 477 twice.
 478
 479    If you think you have found some way in which the GNU C Library does
 480 not conform to the ISO and POSIX standards (*note Standards and
 481 Portability::), that is definitely a bug.  Report it!
 482
 483    Once you're sure you've found a bug, try to narrow it down to the
 484 smallest test case that reproduces the problem.  In the case of a C
 485 library, you really only need to narrow it down to one library function
 486 call, if possible.  This should not be too difficult.
 487
 488    The final step when you have a simple test case is to report the bug.
 489 Do this at <http://www.gnu.org/software/libc/bugs.html>.
 490
 491    If you are not sure how a function should behave, and this manual
 492 doesn't tell you, that's a bug in the manual.  Report that too!  If the
 493 function's behavior disagrees with the manual, then either the library
 494 or the manual has a bug, so report the disagreement.  If you find any
 495 errors or omissions in this manual, please report them to the bug
 496 database.  If you refer to specific sections of the manual, please
 497 include the section names for easier identification.