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.gwdg.de'.
  24 `ftp.gwdg.de' has the crypt distribution in `pub/linux/glibc'.  (Most
  25 non-US mirrors of `ftp.gnu.org' will have it too.)  The file you need
  26 is `glibc-crypt-VERSION.tar.gz'.
  27
  28    You will need recent versions of several GNU tools: definitely GCC
  29 and GNU Make, and possibly others.  *Note Tools for Compilation::,
  30 below.
  31
  32 Configuring and compiling GNU Libc
  33 ==================================
  34
  35    GNU Libc can be compiled in the source directory but we'd advise to
  36 build in a separate build directory.  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    Please note that even if you're building in a separate build
  46 directory, the compiliation needs to modify a few files in the source
  47 directory, especially some files in the manual subdirectory.
  48
  49 `configure' takes many options, but you can get away with knowing only
  50 two: `--prefix' and `--enable-add-ons'.  The `--prefix' option tells
  51 configure where you want glibc installed.  This defaults to
  52 `/usr/local'.  The `--enable-add-ons' option tells configure to use all
  53 the add-on bundles it finds in the source directory.  Since important
  54 functionality is provided in add-ons, you should always give this
  55 option.
  56
  57    It may also be useful to set the CC and CFLAGS variables in the
  58 environment when running `configure'.  CC selects the C compiler that
  59 will be used, and CFLAGS sets optimization options for the compiler.
  60
  61    Here are all the useful options known by `configure':
  62
  63 `--prefix=DIRECTORY'
  64      Install machine-independent data files in subdirectories of
  65      `DIRECTORY'.  The default is to install in `/usr/local'.
  66
  67 `--exec-prefix=DIRECTORY'
  68      Install the library and other machine-dependent files in
  69      subdirectories of `DIRECTORY'.  The default is to the `--prefix'
  70      directory if that option is given, or `/usr/local' otherwise.
  71
  72 `--with-headers=DIRECTORY'
  73      Look for kernel header files in DIRECTORY, not `/usr/include'.
  74      Glibc needs information from the kernel's private header files.
  75      It will normally look in `/usr/include' for them, but if you give
  76      this option, it will look in DIRECTORY instead.
  77
  78      This option is primarily of use on a system where the headers in
  79      `/usr/include' come from an older version of glibc.  Conflicts can
  80      occasionally happen in this case.  Note that Linux libc5 qualifies
  81      as an older version of glibc.  You can also use this option if you
  82      want to compile glibc with a newer set of kernel headers than the
  83      ones found in `/usr/include'.
  84
  85 `--enable-add-ons[=LIST]'
  86      Enable add-on packages in your source tree.  If this option is
  87      given with no list, it enables all the add-on packages it finds.
  88      If you do not wish to use some add-on package that you have
  89      present in your source tree, give this option a list of the
  90      add-ons that you _do_ want used, like this:
  91      `--enable-add-ons=crypt,linuxthreads'
  92
  93 `--with-binutils=DIRECTORY'
  94      Use the binutils (assembler and linker) in `DIRECTORY', not the
  95      ones the C compiler would default to.  You could use this option if
  96      the default binutils on your system cannot deal with all the
  97      constructs in the GNU C library.  (`configure' will detect the
  98      problem and suppress these constructs, so the library will still
  99      be usable, but functionality may be lost--for example, you can not
 100      build a shared libc with old binutils.)
 101
 102 `--without-fp'
 103      Use this option if your computer lacks hardware floating-point
 104      support and your operating system does not emulate an FPU.
 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' and add the
 148      appropriate compiler flags (`-mcpu=i386' will do the trick) to
 149      CFLAGS. (A library compiled for a Pentium (`i586') will still work
 150      on a 386, but it may be slower.)
 151
 152      If you give just `--build', configure will get confused.
 153
 154    To build the library and related programs, type `make'.  This will
 155 produce a lot of output, some of which may look like errors from `make'
 156 but isn't.  Look for error messages from `make' containing `***'.
 157 Those indicate that something is really wrong.
 158
 159    The compilation process takes several hours even on fast hardware.
 160 Expect at least two hours for the default configuration on i586 for
 161 Linux.  For Hurd times are much longer.  Except for EGCS 1.1 (and later
 162 versions of EGCS), all supported versions of GCC have a problem which
 163 causes them to take several minutes to compile certain files in the
 164 iconvdata directory.  Do not panic if the compiler appears to hang.
 165
 166    If you want to run a parallel make, you can't just give `make' the
 167 `-j' option, because it won't be passed down to the sub-makes.
 168 Instead, edit the generated `Makefile' and uncomment the line
 169
 170      # PARALLELMFLAGS = -j 4
 171
 172 You can change the `4' to some other number as appropriate for your
 173 system.  Instead of changing the `Makefile', you could give this option
 174 directly to `make' and call it as, e.g.  `make PARALLELMFLAGS=-j4'.  If
 175 you're building in the source directory, you've got to use the latter
 176 approach since in this case no new `Makefile' is generated which you
 177 can change.
 178
 179    To build and run some test programs which exercise some of the
 180 library facilities, type `make check'.  This should complete
 181 successfully; if it doesn't, do not use the built library, and report a
 182 bug.  *Note Reporting Bugs::, for how to do that.  Note that some of
 183 the tests assume they are not being run by `root'.  We recommend you
 184 compile and test glibc as an unprivileged user.
 185
 186    To format the `GNU C Library Reference Manual' for printing, type
 187 `make dvi'.  You need a working TeX installation to do this.  The
 188 distribution already includes the on-line formatted version of the
 189 manual, as Info files.  You can regenerate those with `make info', but
 190 it shouldn't be necessary.
 191
 192 Installing the C Library
 193 ========================
 194
 195    To install the library and its header files, and the Info files of
 196 the manual, type `make install'.  This will build things if necessary,
 197 before installing them.  Don't rely on that; compile everything first.
 198 If you are installing glibc as your primary C library, we recommend you
 199 shut the system down to single-user mode first, and reboot afterward.
 200 This minimizes the risk of breaking things when the library changes out
 201 from underneath.
 202
 203    If you are upgrading from a previous installation of glibc 2.0 or
 204 2.1, `make install' will do the entire job.  If you're upgrading from
 205 Linux libc5 or some other C library, you need to rename the old
 206 `/usr/include' directory out of the way before running `make install',
 207 or you will end up with a mixture of header files from both libraries,
 208 and you won't be able to compile anything.  You may also need to
 209 reconfigure GCC to work with the new library.  The easiest way to do
 210 that is to figure out the compiler switches to make it work again
 211 (`-Wl,--dynamic-linker=/lib/ld-linux.so.2' should work on Linux
 212 systems) and use them to recompile gcc.  You can also edit the specs
 213 file (`/usr/lib/gcc-lib/TARGET/VERSION/specs'), but that is a bit of a
 214 black art.
 215
 216    You can install glibc somewhere other than where you configured it
 217 to go by setting the `install_root' variable on the command line for
 218 `make install'.  The value of this variable is prepended to all the
 219 paths for installation.  This is useful when setting up a chroot
 220 environment or preparing a binary distribution.
 221
 222    Glibc 2.1 includes two daemons, `nscd' and `utmpd', which you may or
 223 may not want to run.  `nscd' caches name service lookups; it can
 224 dramatically improve performance with NIS+, and may help with DNS as
 225 well.  `utmpd' allows programs that use the old format for the `utmp'
 226 file to coexist with new programs.  For more information see the file
 227 `login/README.utmpd'.
 228
 229    One auxiliary program, `/usr/libexec/pt_chown', is installed setuid
 230 `root'.  This program is invoked by the `grantpt' function; it sets the
 231 permissions on a pseudoterminal so it can be used by the calling
 232 process.  This means programs like `xterm' and `screen' do not have to
 233 be setuid to get a pty.  (There may be other reasons why they need
 234 privileges.)  If you are using a 2.1 or newer Linux kernel with the
 235 `devptsfs' or `devfs' filesystems providing pty slaves, you don't need
 236 this program; otherwise you do.  The source for `pt_chown' is in
 237 `login/programs/pt_chown.c'.
 238
 239 Recommended Tools for Compilation
 240 =================================
 241
 242    We recommend installing the following GNU tools before attempting to
 243 build the GNU C library:
 244
 245    * GNU `make' 3.75
 246
 247      You need the latest version of GNU `make'.  Modifying the GNU C
 248      Library to work with other `make' programs would be so hard that we
 249      recommend you port GNU `make' instead.  *Really.*  We recommend
 250      version GNU `make' version 3.75 or 3.77.  All earlier versions
 251      have severe bugs or lack features. Version 3.76 is known to have
 252      bugs which only show up in big projects like GNU `libc'.  Version
 253      3.76.1 seems OK but some people have reported problems.
 254
 255    * EGCS 1.1.1, 1.1 or 1.0.3, or GCC 2.8.1
 256
 257      The GNU C library can only be compiled with the GNU C compiler
 258      family.  As of the 2.1 release, EGCS 1.0.3 or higher is required.
 259      GCC 2.8.1 can also be used (but see the FAQ for reasons why you
 260      might not want to).  Earlier versions simply are too buggy.
 261
 262      You can use whatever compiler you like to compile programs that
 263      use GNU libc, but be aware that both GCC 2.7 and 2.8 have bugs in
 264      their floating-point support that may be triggered by the math
 265      library.
 266
 267      On Alpha machines you need at least EGCS 1.1.1.  Earlier versions
 268      don't work reliably.
 269
 270      For PPC you might need some patches even on top of the last EGCS
 271      version.  See the FAQ.
 272
 273    * GNU `binutils' 2.9.1, 2.9.1.0.16, or later 2.9.1.0.x release
 274
 275      You must use GNU binutils (as and ld) if you want to build a shared
 276      library.  Even if you don't, we recommend you use them anyway.  No
 277      one has tested compilation with non-GNU binutils in a long time.
 278
 279      The quality of binutils releases has varied a bit recently.  The
 280      bugs are in obscure features, but glibc uses quite a few of those.
 281      2.9.1, 2.9.1.0.16, and later 2.9.1.0.x releases are known to
 282      work.  Versions after 2.8.1.0.23 may or may not work.  Older
 283      versions definitely don't.  2.9.1.0.16 or higher is required on
 284      some platforms, like PPC and Arm.
 285
 286      For PPC you might need some patches even on top of the last
 287      binutils version.  See the FAQ.
 288
 289    * GNU `texinfo' 3.12f
 290
 291      To correctly translate and install the Texinfo documentation you
 292      need this version of the `texinfo' package.  Earlier versions do
 293      not understand all the tags used in the document, and the
 294      installation mechanism for the info files is not present or works
 295      differently.
 296
 297    * GNU `awk' 3.0, or some other POSIX awk
 298
 299      Awk is used in several places to generate files.  The scripts
 300      should work with any POSIX-compliant awk implementation; `gawk'
 301      3.0 and `mawk' 1.3 are known to work.
 302
 303    * Perl 5
 304
 305      Perl is not required, but it is used if present to test the
 306      installation.  We may decide to use it elsewhere in the future.
 307
 308
 309 If you change any of the `configure.in' files you will also need
 310
 311    * GNU `autoconf' 2.12 or higher
 312
 313 and if you change any of the message translation files you will need
 314
 315    * GNU `gettext' 0.10.35 or later (version 0.10.35 is a alpha release
 316      and available via ftp from alpha.gnu.org/gnu)
 317
 318 You may also need these packages if you upgrade your source tree using
 319 patches, although we try to avoid this.
 320
 321 Supported Configurations
 322 ========================
 323
 324    The GNU C Library currently supports configurations that match the
 325 following patterns:
 326
 327      alpha-*-linux
 328      arm-*-linux
 329      arm-*-linuxaout
 330      arm-*-none
 331      iX86-*-gnu
 332      iX86-*-linux
 333      m68k-*-linux
 334      powerpc-*-linux
 335      sparc-*-linux
 336      sparc64-*-linux
 337
 338    Former releases of this library (version 1.09.1 and perhaps earlier
 339 versions) used to run on the following configurations:
 340
 341      alpha-dec-osf1
 342      alpha-*-linuxecoff
 343      iX86-*-bsd4.3
 344      iX86-*-isc2.2
 345      iX86-*-isc3.N
 346      iX86-*-sco3.2
 347      iX86-*-sco3.2v4
 348      iX86-*-sysv
 349      iX86-*-sysv4
 350      iX86-force_cpu386-none
 351      iX86-sequent-bsd
 352      i960-nindy960-none
 353      m68k-hp-bsd4.3
 354      m68k-mvme135-none
 355      m68k-mvme136-none
 356      m68k-sony-newsos3
 357      m68k-sony-newsos4
 358      m68k-sun-sunos4.N
 359      mips-dec-ultrix4.N
 360      mips-sgi-irix4.N
 361      sparc-sun-solaris2.N
 362      sparc-sun-sunos4.N
 363
 364    Since no one has volunteered to test and fix these configurations,
 365 they are not supported at the moment.  They probably don't compile;
 366 they definitely don't work anymore.  Porting the library is not hard.
 367 If you are interested in doing a port, please contact the glibc
 368 maintainers by sending electronic mail to <bug-glibc@gnu.org>.
 369
 370    Each case of `iX86' can be `i386', `i486', `i586', or `i686'.  All
 371 of those configurations produce a library that can run on any of these
 372 processors if the compiler is configured correctly.  The GCC compiler
 373 by default generates code that's optimized for the machine it's
 374 configured for and will use the instructions available on that machine.
 375 For example if your GCC is configured for `i686', gcc will optimize
 376 for `i686' and might issue some `i686' specific instructions.  To
 377 generate code for other models you should give GCC the appropriate
 378 `-march=' and `-mcpu=' compiler switches via CFLAGS.
 379
 380 Specific advice for Linux systems
 381 =================================
 382
 383    If you are installing GNU libc on a Linux system, you need to have
 384 the header files from a 2.2 kernel around for reference.  You do not
 385 need to use the 2.2 kernel, just have its headers where glibc can get
 386 at them.  The easiest way to do this is to unpack it in a directory
 387 such as `/usr/src/linux-2.2.1'.  In that directory, run `make config'
 388 and accept all the defaults.  Then run `make include/linux/version.h'.
 389 Finally, configure glibc with the option
 390 `--with-headers=/usr/src/linux-2.2.1/include'.  Use the most recent
 391 kernel you can get your hands on.
 392
 393    An alternate tactic is to unpack the 2.2 kernel and run `make
 394 config' as above.  Then rename or delete `/usr/include', create a new
 395 `/usr/include', and make the usual symbolic links of
 396 `/usr/include/linux' and `/usr/include/asm' into the 2.2 kernel
 397 sources.  You can then configure glibc with no special options.  This
 398 tactic is recommended if you are upgrading from libc5, since you need
 399 to get rid of the old header files anyway.
 400
 401    Note that `/usr/include/net' and `/usr/include/scsi' should *not* be
 402 symlinks into the kernel sources.  GNU libc provides its own versions
 403 of these files.
 404
 405    Linux expects some components of the libc installation to be in
 406 `/lib' and some in `/usr/lib'.  This is handled automatically if you
 407 configure glibc with `--prefix=/usr'.  If you set some other prefix or
 408 allow it to default to `/usr/local', then all the components are
 409 installed there.
 410
 411    If you are upgrading from libc5, you need to recompile every shared
 412 library on your system against the new library for the sake of new code,
 413 but keep the old libraries around for old binaries to use.  This is
 414 complicated and difficult.  Consult the Glibc2 HOWTO at
 415 <http://www.imaxx.net/~thrytis/glibc> for details.
 416
 417    You cannot use `nscd' with 2.0 kernels, due to bugs in the
 418 kernel-side thread support.  `nscd' happens to hit these bugs
 419 particularly hard, but you might have problems with any threaded
 420 program.
 421
 422 Reporting Bugs
 423 ==============
 424
 425    There are probably bugs in the GNU C library.  There are certainly
 426 errors and omissions in this manual.  If you report them, they will get
 427 fixed.  If you don't, no one will ever know about them and they will
 428 remain unfixed for all eternity, if not longer.
 429
 430    It is a good idea to check first that the problem was not reported
 431 before.  Bugs are documented in two places: The file `BUGS' describes a
 432 number of well known bugs and the bug tracking system has a WWW
 433 interface at <http://www-gnats.gnu.org:8080/cgi-bin/wwwgnats.pl>.  The
 434 WWW interface gives you access to open and closed reports.  The closed
 435 reports normally include a patch or a hint on solving the problem.
 436
 437    To report a bug, first you must find it.  Hopefully, this will be the
 438 hard part.  Once you've found a bug, make sure it's really a bug.  A
 439 good way to do this is to see if the GNU C library behaves the same way
 440 some other C library does.  If so, probably you are wrong and the
 441 libraries are right (but not necessarily).  If not, one of the libraries
 442 is probably wrong.  It might not be the GNU library.  Many historical
 443 Unix C libraries permit things that we don't, such as closing a file
 444 twice.
 445
 446    If you think you have found some way in which the GNU C library does
 447 not conform to the ISO and POSIX standards (*note Standards and
 448 Portability::.), that is definitely a bug.  Report it!
 449
 450    Once you're sure you've found a bug, try to narrow it down to the
 451 smallest test case that reproduces the problem.  In the case of a C
 452 library, you really only need to narrow it down to one library function
 453 call, if possible.  This should not be too difficult.
 454
 455    The final step when you have a simple test case is to report the bug.
 456 Do this using the `glibcbug' script.  It is installed with libc, or if
 457 you haven't installed it, will be in your build directory.  Send your
 458 test case, the results you got, the results you expected, and what you
 459 think the problem might be (if you've thought of anything).  `glibcbug'
 460 will insert the configuration information we need to see, and ship the
 461 report off to <bugs@gnu.org>.  Don't send a message there directly; it
 462 is fed to a program that expects mail to be formatted in a particular
 463 way.  Use the script.
 464
 465    If you are not sure how a function should behave, and this manual
 466 doesn't tell you, that's a bug in the manual.  Report that too!  If the
 467 function's behavior disagrees with the manual, then either the library
 468 or the manual has a bug, so report the disagreement.  If you find any
 469 errors or omissions in this manual, please report them to the Internet
 470 address <bug-glibc-manual@gnu.org>.  If you refer to specific sections
 471 when reporting on the manual, please include the section names for
 472 easier identification.
 473