INSTALL

   1 Installing the GNU C Library
   2 ****************************
   3
   4    Before you do anything else, you should read the file `FAQ' found at
   5 the top level of the source tree.  This file answers common questions
   6 and describes problems you may experience with compilation and
   7 installation.  It is updated more frequently than this manual.
   8
   9    Features can be added to GNU Libc via "add-on" bundles.  These are
  10 separate tarfiles which you unpack into the top level of the source
  11 tree.  Then you give `configure' the `--enable-add-ons' option to
  12 activate them, and they will be compiled into the library.  As of the
  13 2.1 release, two important components of glibc are distributed as
  14 "official" add-ons.  Unless you are doing an unusual installation, you
  15 should get them both.
  16
  17    Support for POSIX threads is maintained by someone else, so it's in a
  18 separate package.  It is only available for Linux systems, but this will
  19 change in the future.  Get it from the same place you got the main
  20 bundle; the file is `glibc-linuxthreads-VERSION.tar.gz'.  Support for
  21 the `crypt' function is distributed separately because of United States
  22 export restrictions.  If you are outside the US or Canada, you must get
  23 `crypt' support from a site outside the US, such as `ftp.ifi.uio.no'.
  24 (Most non-US mirrors of `ftp.gnu.org' will have it too.)  The file you
  25 need is `glibc-crypt-VERSION.tar.gz'.
  26
  27    You will need recent versions of several GNU tools: definitely GCC
  28 and GNU Make, and possibly others.  *Note Tools for Compilation::,
  29 below.
  30
  31 Configuring and compiling GNU Libc
  32 ==================================
  33
  34    GNU Libc cannot be compiled in the source directory.  You must
  35 create a separate directory for the object files.  This directory
  36 should be outside the source tree.  For example, if you have unpacked
  37 the glibc sources in `/src/gnu/glibc-2.1.0', create a directory
  38 `/src/gnu/glibc-build' to put the object files in.
  39
  40    From your object directory, run the shell script `configure' found
  41 at the top level of the source tree.  In the scenario above, you'd type
  42
  43      $ ../glibc-2.1.0/configure ARGS...
  44
  45 `configure' takes many options, but you can get away with knowing only
  46 two: `--prefix' and `--enable-add-ons'.  The `--prefix' option tells
  47 configure where you want glibc installed.  This defaults to
  48 `/usr/local'.  The `--enable-add-ons' option tells configure to use all
  49 the add-on bundles it finds in the source directory.  Since important
  50 functionality is provided in add-ons, you should always give this
  51 option.
  52
  53    It may also be useful to set the CC and CFLAGS variables in the
  54 environment when running `configure'.  CC selects the C compiler that
  55 will be used, and CFLAGS sets optimization options for the compiler.
  56
  57    Here are all the useful options known by `configure':
  58
  59 `--prefix=DIRECTORY'
  60      Install machine-independent data files in subdirectories of
  61      `DIRECTORY'.  The default is to install in `/usr/local'.
  62
  63 `--exec-prefix=DIRECTORY'
  64      Install the library and other machine-dependent files in
  65      subdirectories of `DIRECTORY'.  The default is to the `--prefix'
  66      directory if that option is given, or `/usr/local' otherwise.
  67
  68 `--with-headers=DIRECTORY'
  69      Look for kernel header files in DIRECTORY, not `/usr/include'.
  70      Glibc needs information from the kernel's private header files.
  71      It will normally look in `/usr/include' for them, but if you give
  72      this option, it will look in DIRECTORY instead.
  73
  74      This option is primarily of use on a system where the headers in
  75      `/usr/include' come from an older version of glibc.  Conflicts can
  76      occasionally happen in this case.  Note that Linux libc5 qualifies
  77      as an older version of glibc.  You can also use this option if you
  78      want to compile glibc with a newer set of kernel headers than the
  79      ones found in `/usr/include'.
  80
  81 `--enable-add-ons[=LIST]'
  82      Enable add-on packages in your source tree.  If this option is
  83      given with no list, it enables all the add-on packages it finds.
  84      If you do not wish to use some add-on package that you have
  85      present in your source tree, give this option a list of the
  86      add-ons that you *do* want used, like this:
  87      `--enable-add-ons=crypt,linuxthreads'
  88
  89 `--with-binutils=DIRECTORY'
  90      Use the binutils (assembler and linker) in `DIRECTORY', not the
  91      ones the C compiler would default to.  You could use this option if
  92      the default binutils on your system cannot deal with all the
  93      constructs in the GNU C library.  (`configure' will detect the
  94      problem and suppress these constructs, so the library will still
  95      be usable, but functionality may be lost--for example, you can not
  96      build a shared libc with old binutils.)
  97
  98 `--without-fp'
  99      Use this option if your computer lacks hardware floating-point
 100      support and your operating system does not emulate an FPU.
 101
 102 `--disable-static'
 103      Don't build static libraries.  Static libraries aren't that useful
 104      these days, but we recommend you build them in case you need them.
 105
 106 `--disable-shared'
 107      Don't build shared libraries even if we could.  Not all systems
 108      support shared libraries; you need ELF support and (currently) the
 109      GNU linker.
 110
 111 `--disable-profile'
 112      Don't build libraries with profiling information.  You may want to
 113      use this option if you don't plan to do profiling.
 114
 115 `--enable-omitfp'
 116      Use maximum optimization for the normal (static and shared)
 117      libraries, and compile separate static libraries with debugging
 118      information and no optimisation.  We recommend against this.  The
 119      extra optimization doesn't gain you much, it may provoke compiler
 120      bugs, and you won't be able to trace bugs through the C library.
 121
 122 `--disable-versioning'
 123      Don't compile the shared libraries with symbol version information.
 124      Doing this will make the library that's built incompatible with old
 125      binaries, so it's not recommended.
 126
 127 `--enable-static-nss'
 128      Compile static versions of the NSS (Name Service Switch) libraries.
 129      This is not recommended because it defeats the purpose of NSS; a
 130      program linked statically with the NSS libraries cannot be
 131      dynamically reconfigured to use a different name database.
 132
 133 `--build=BUILD-SYSTEM'
 134 `--host=HOST-SYSTEM'
 135      These options are for cross-compiling.  If you give them both and
 136      BUILD-SYSTEM is different from HOST-SYSTEM, `configure' will
 137      prepare to cross-compile glibc from BUILD-SYSTEM to be used on
 138      HOST-SYSTEM.  You'll probably need the `--with-headers' option
 139      too, and you may have to override CONFIGURE's selection of the
 140      compiler and/or binutils.
 141
 142      If you give just `--host', configure will prepare for a native
 143      compile but use what you say instead of guessing what your system
 144      is.  This is most useful to change the CPU submodel.  For example,
 145      if configure guesses your machine as `i586-pc-linux-gnu' but you
 146      want to compile a library optimized for 386es, give
 147      `--host=i386-pc-linux-gnu' or just `--host=i386-linux'.  (A
 148      library compiled for a Pentium (`i586') will still work on a 386,
 149      but it may be slower.)
 150
 151      If you give just `--build', configure will get confused.
 152
 153    To build the library and related programs, type `make'.  This will
 154 produce a lot of output, some of which may look like errors from `make'
 155 but isn't.  Look for error messages from `make' containing `***'.
 156 Those indicate that something is really wrong.
 157
 158    The compilation process takes several hours even on fast hardware.
 159 Expect at least two hours for the default configuration on i586 for
 160 Linux.  For Hurd times are much longer.  Except for EGCS 1.1 (and later
 161 versions of EGCS), all supported versions of GCC have a problem which
 162 causes them to take several minutes to compile certain files in the
 163 iconvdata directory.  Do not panic if the compiler appears to hang.
 164
 165    If you want to run a parallel make, you can't just give `make' the
 166 `-j' option, because it won't be passed down to the sub-makes.
 167 Instead, edit the generated `Makefile' and uncomment the line
 168
 169      # PARALLELMFLAGS = -j 4
 170
 171 You can change the `4' to some other number as appropriate for your
 172 system.
 173
 174    To build and run some test programs which exercise some of the
 175 library facilities, type `make check'.  This should complete
 176 successfully; if it doesn't, do not use the built library, and report a
 177 bug.  *Note Reporting Bugs::, for how to do that.  Note that some of
 178 the tests assume they are not being run by `root'.  We recommend you
 179 compile and test glibc as an unprivileged user.
 180
 181    To format the `GNU C Library Reference Manual' for printing, type
 182 `make dvi'.  You need a working TeX installation to do this.  The
 183 distribution already includes the on-line formatted version of the
 184 manual, as Info files.  You can regenerate those with `make info', but
 185 it shouldn't be necessary.
 186
 187 Installing the C Library
 188 ========================
 189
 190    To install the library and its header files, and the Info files of
 191 the manual, type `make install'.  This will build things if necessary,
 192 before installing them.  Don't rely on that; compile everything first.
 193 If you are installing glibc as your primary C library, we recommend you
 194 shut the system down to single-user mode first, and reboot afterward.
 195 This minimizes the risk of breaking things when the library changes out
 196 from underneath.
 197
 198    If you are upgrading from a previous installation of glibc 2.0 or
 199 2.1, `make install' will do the entire job.  If you're upgrading from
 200 Linux libc5 or some other C library, you need to rename the old
 201 `/usr/include' directory out of the way first, or you will end up with
 202 a mixture of header files from both libraries, and you won't be able to
 203 compile anything.  You may also need to reconfigure GCC to work with
 204 the new library.  The easiest way to do that is to figure out the
 205 compiler switches to make it work again
 206 (`-Wl,-dynamic-linker=/lib/ld-linux.so.2' should work on Linux systems)
 207 and use them to recompile gcc.  You can also edit the specs file
 208 (`/usr/lib/gcc-lib/TARGET/VERSION/specs'), but that is a bit of a black
 209 art.
 210
 211    You can install glibc somewhere other than where you configured it
 212 to go by setting the `install_root' variable on the command line for
 213 `make install'.  The value of this variable is prepended to all the
 214 paths for installation.  This is useful when setting up a chroot
 215 environment or preparing a binary distribution.
 216
 217    Glibc 2.1 includes two daemons, `nscd' and `utmpd', which you may or
 218 may not want to run.  `nscd' caches name service lookups; it can
 219 dramatically improve performance with NIS+, and may help with DNS as
 220 well.  `utmpd' allows programs that use the old format for the `utmp'
 221 file to coexist with new programs.  For more information see the files
 222 `nscd/README' and `login/README.utmpd'.
 223
 224    One auxiliary program, `/usr/libexec/pt_chown', is installed setuid
 225 `root'.  This program is invoked by the `grantpt' function; it sets the
 226 permissions on a pseudoterminal so it can be used by the calling
 227 process.  This means programs like `xterm' and `screen' do not have to
 228 be setuid to get a pty.  (There may be other reasons why they need
 229 privileges.)  If you are using a 2.1 Linux kernel with the `devptsfs'
 230 or `devfs' filesystems providing pty slaves, you don't need this
 231 program; otherwise you do.  The source for `pt_chown' is in
 232 `login/programs/pt_chown.c'.
 233
 234 Recommended Tools for Compilation
 235 =================================
 236
 237    We recommend installing the following GNU tools before attempting to
 238 build the GNU C library:
 239
 240    * GNU `make' 3.75
 241
 242      You need the latest version of GNU `make'.  Modifying the GNU C
 243      Library to work with other `make' programs would be so hard that we
 244      recommend you port GNU `make' instead.  *Really.*  We recommend
 245      version GNU `make' version 3.75 or 3.77.  All earlier versions
 246      have severe bugs or lack features. Version 3.76 is known to have
 247      bugs which only show up in big projects like GNU `libc'.  Version
 248      3.76.1 seems OK but some people have reported problems.
 249
 250    * EGCS 1.1.1, 1.1 or 1.0.3
 251
 252      The GNU C library can only be compiled with the GNU C compiler
 253      family.  We recommend EGCS 1.0.3 or higher.  GCC 2.8.1 and older
 254      versions of EGCS may have problems, particularly on non-Intel
 255      architectures.  GCC 2.7.x has catastrophic bugs and cannot be used
 256      at all.  (You can use GCC 2.7.x to compile programs that use GNU
 257      libc, but you may have problems, particularly with the math
 258      functions.)
 259
 260      On Alpha machines you need at least EGCS 1.1.1.  Earlier versions
 261      don't work reliably.
 262
 263      For PPC you might need some patches even on top of the last EGCS
 264      version.  See the FAQ.
 265
 266    * GNU `binutils' 2.9.1, or 2.9.1.0.16
 267
 268      You must use GNU binutils (as and ld) if you want to build a shared
 269      library.  Even if you don't, we recommend you use them anyway.  No
 270      one has tested compilation with non-GNU binutils in a long time.
 271
 272      The quality of binutils releases has varied a bit recently.  The
 273      bugs are in obscure features, but glibc uses quite a few of those.
 274      2.9.1 and 2.9.1.0.16 are known to work.  Versions after 2.8.1.0.23
 275      may or may not work.  Older versions definitely don't.  2.9.1.0.16
 276      is required on some platforms, like PPC and Arm.
 277
 278      For PPC you might need some patches even on top of the last
 279      binutils version.  See the FAQ.
 280
 281    * GNU `texinfo' 3.11
 282
 283      To correctly translate and install the Texinfo documentation you
 284      need this version of the `texinfo' package.  Earlier versions do
 285      not understand all the tags used in the document, and the
 286      installation mechanism for the info files is not present or works
 287      differently.
 288
 289    * GNU `awk' 3.0, or some other POSIX awk
 290
 291      Awk is used in several places to generate files.  The scripts
 292      should work with any POSIX-compliant awk implementation; `gawk'
 293      3.0 and `mawk' 1.3 are known to work.
 294
 295    * Perl 5
 296
 297      Perl is not required, but it is used if present to test the
 298      installation.  We may decide to use it elsewhere in the future.
 299
 300 If you change any of the `configure.in' files you will also need
 301
 302    * GNU `autoconf' 2.12
 303
 304 and if you change any of the message translation files you will need
 305
 306    * GNU `gettext' 0.10.35 or later
 307
 308 You may also need these packages if you upgrade your source tree using
 309 patches, although we try to avoid this.
 310
 311 Supported Configurations
 312 ========================
 313
 314    The GNU C Library currently supports configurations that match the
 315 following patterns:
 316
 317      alpha-*-linux
 318      arm-*-linux
 319      arm-*-linuxaout
 320      arm-*-none
 321      iX86-*-gnu
 322      iX86-*-linux
 323      m68k-*-linux
 324      powerpc-*-linux
 325      sparc-*-linux
 326      sparc64-*-linux
 327
 328    Former releases of this library (version 1.09.1 and perhaps earlier
 329 versions) used to run on the following configurations:
 330
 331      alpha-dec-osf1
 332      alpha-*-linuxecoff
 333      iX86-*-bsd4.3
 334      iX86-*-isc2.2
 335      iX86-*-isc3.N
 336      iX86-*-sco3.2
 337      iX86-*-sco3.2v4
 338      iX86-*-sysv
 339      iX86-*-sysv4
 340      iX86-force_cpu386-none
 341      iX86-sequent-bsd
 342      i960-nindy960-none
 343      m68k-hp-bsd4.3
 344      m68k-mvme135-none
 345      m68k-mvme136-none
 346      m68k-sony-newsos3
 347      m68k-sony-newsos4
 348      m68k-sun-sunos4.N
 349      mips-dec-ultrix4.N
 350      mips-sgi-irix4.N
 351      sparc-sun-solaris2.N
 352      sparc-sun-sunos4.N
 353
 354    Since no one has volunteered to test and fix these configurations,
 355 they are not supported at the moment.  They probably don't compile;
 356 they definitely don't work anymore.  Porting the library is not hard.
 357 If you are interested in doing a port, please contact the glibc
 358 maintainers by sending electronic mail to <bug-glibc@gnu.org>.
 359
 360    Each case of `iX86' can be `i386', `i486', `i586', or `i686'.  All
 361 of those configurations produce a library that can run on any of these
 362 processors.  The library will be optimized for the specified processor,
 363 but will not use instructions not available on all of them.  If you
 364 want the library to use instructions only available on newer
 365 processors, give GCC the appropriate `-m' switches via CFLAGS.
 366
 367 Specific advice for Linux systems
 368 =================================
 369
 370    If you are installing GNU libc on a Linux system, you need to have
 371 the header files from a development kernel around for reference.  You
 372 do not need to use the development kernel, just have its headers where
 373 glibc can get at them.  The easiest way to do this is to unpack a
 374 development kernel in a directory such as `/usr/src/linux-dev'.  In that
 375 directory, run `make config' and accept all the defaults.  Then
 376 configure glibc with the option
 377 `--with-headers=/usr/src/linux-dev/include'.  Use the latest
 378 development kernel you can get your hands on.
 379
 380    An alternate tactic is to unpack the development kernel and run
 381 `make config' as above.  Then rename or delete `/usr/include', create a
 382 new `/usr/include', and make the usual symbolic links of
 383 `/usr/include/linux' and `/usr/include/asm' into the development kernel
 384 sources.  You can then configure glibc with no special options.  This
 385 tactic is recommended if you are upgrading from libc5, since you need
 386 to get rid of the old header files anyway.
 387
 388    Note that `/usr/include/net' and `/usr/include/scsi' should *not* be
 389 symlinks into the kernel sources.  GNU libc provides its own versions
 390 of these files.
 391
 392    Linux expects some components of the libc installation to be in
 393 `/lib' and some in `/usr/lib'.  This is handled automatically if you
 394 configure glibc with `--prefix=/usr'.  If you set some other prefix or
 395 allow it to default to `/usr/local', then all the components are
 396 installed there.
 397
 398    If you are upgrading from libc5, you need to recompile every shared
 399 library on your system against the new library for the sake of new code,
 400 but keep the old libraries around for old binaries to use.  This is
 401 complicated and difficult.  Consult the Glibc2 HOWTO at
 402 `http://www.imaxx.net/~thrytis/glibc' for details.
 403
 404    You cannot use `nscd' with 2.0 kernels, due to bugs in the
 405 kernel-side thread support.  `nscd' happens to hit these bugs
 406 particularly hard, but you might have problems with any threaded
 407 program.
 408
 409 Reporting Bugs
 410 ==============
 411
 412    There are probably bugs in the GNU C library.  There are certainly
 413 errors and omissions in this manual.  If you report them, they will get
 414 fixed.  If you don't, no one will ever know about them and they will
 415 remain unfixed for all eternity, if not longer.
 416
 417    To report a bug, first you must find it.  Hopefully, this will be the
 418 hard part.  Once you've found a bug, make sure it's really a bug.  A
 419 good way to do this is to see if the GNU C library behaves the same way
 420 some other C library does.  If so, probably you are wrong and the
 421 libraries are right (but not necessarily).  If not, one of the libraries
 422 is probably wrong.  It might not be the GNU library.  Many historical
 423 Unix C libraries permit things that we don't, such as closing a file
 424 twice.
 425
 426    If you think you have found some way in which the GNU C library does
 427 not conform to the ISO and POSIX standards (*note Standards and
 428 Portability::.), that is definitely a bug.  Report it!
 429
 430    Once you're sure you've found a bug, try to narrow it down to the
 431 smallest test case that reproduces the problem.  In the case of a C
 432 library, you really only need to narrow it down to one library function
 433 call, if possible.  This should not be too difficult.
 434
 435    The final step when you have a simple test case is to report the bug.
 436 Do this using the `glibcbug' script.  It is installed with libc, or if
 437 you haven't installed it, will be in your build directory.  Send your
 438 test case, the results you got, the results you expected, and what you
 439 think the problem might be (if you've thought of anything).  `glibcbug'
 440 will insert the configuration information we need to see, and ship the
 441 report off to <bug-glibc@gnu.org>.  Don't send a message there
 442 directly; it is fed to a program that expects mail to be formatted in a
 443 particular way.  Use the script.
 444
 445    If you are not sure how a function should behave, and this manual
 446 doesn't tell you, that's a bug in the manual.  Report that too!  If the
 447 function's behavior disagrees with the manual, then either the library
 448 or the manual has a bug, so report the disagreement.  If you find any
 449 errors or omissions in this manual, please report them to the Internet
 450 address <bug-glibc-manual@gnu.org>.  If you refer to specific sections
 451 when reporting on the manual, please include the section names for
 452 easier identification.
 453