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 can be compiled in the source directory but we'd advise to
  35 build in a separate build directory.  For example, if you have unpacked
  36 the glibc sources in `/src/gnu/glibc-2.1.0', create a directory
  37 `/src/gnu/glibc-build' to put the object files in.
  38
  39    From your object directory, run the shell script `configure' found
  40 at the top level of the source tree.  In the scenario above, you'd type
  41
  42      $ ../glibc-2.1.0/configure ARGS...
  43
  44 `configure' takes many options, but you can get away with knowing only
  45 two: `--prefix' and `--enable-add-ons'.  The `--prefix' option tells
  46 configure where you want glibc installed.  This defaults to
  47 `/usr/local'.  The `--enable-add-ons' option tells configure to use all
  48 the add-on bundles it finds in the source directory.  Since important
  49 functionality is provided in add-ons, you should always give this
  50 option.
  51
  52    It may also be useful to set the CC and CFLAGS variables in the
  53 environment when running `configure'.  CC selects the C compiler that
  54 will be used, and CFLAGS sets optimization options for the compiler.
  55
  56    Here are all the useful options known by `configure':
  57
  58 `--prefix=DIRECTORY'
  59      Install machine-independent data files in subdirectories of
  60      `DIRECTORY'.  The default is to install in `/usr/local'.
  61
  62 `--exec-prefix=DIRECTORY'
  63      Install the library and other machine-dependent files in
  64      subdirectories of `DIRECTORY'.  The default is to the `--prefix'
  65      directory if that option is given, or `/usr/local' otherwise.
  66
  67 `--with-headers=DIRECTORY'
  68      Look for kernel header files in DIRECTORY, not `/usr/include'.
  69      Glibc needs information from the kernel's private header files.
  70      It will normally look in `/usr/include' for them, but if you give
  71      this option, it will look in DIRECTORY instead.
  72
  73      This option is primarily of use on a system where the headers in
  74      `/usr/include' come from an older version of glibc.  Conflicts can
  75      occasionally happen in this case.  Note that Linux libc5 qualifies
  76      as an older version of glibc.  You can also use this option if you
  77      want to compile glibc with a newer set of kernel headers than the
  78      ones found in `/usr/include'.
  79
  80 `--enable-add-ons[=LIST]'
  81      Enable add-on packages in your source tree.  If this option is
  82      given with no list, it enables all the add-on packages it finds.
  83      If you do not wish to use some add-on package that you have
  84      present in your source tree, give this option a list of the
  85      add-ons that you _do_ want used, like this:
  86      `--enable-add-ons=crypt,linuxthreads'
  87
  88 `--with-binutils=DIRECTORY'
  89      Use the binutils (assembler and linker) in `DIRECTORY', not the
  90      ones the C compiler would default to.  You could use this option if
  91      the default binutils on your system cannot deal with all the
  92      constructs in the GNU C library.  (`configure' will detect the
  93      problem and suppress these constructs, so the library will still
  94      be usable, but functionality may be lost--for example, you can not
  95      build a shared libc with old binutils.)
  96
  97 `--without-fp'
  98      Use this option if your computer lacks hardware floating-point
  99      support and your operating system does not emulate an FPU.
 100
 101 `--disable-static'
 102      Don't build static libraries.  Static libraries aren't that useful
 103      these days, but we recommend you build them in case you need them.
 104
 105 `--disable-shared'
 106      Don't build shared libraries even if we could.  Not all systems
 107      support shared libraries; you need ELF support and (currently) the
 108      GNU linker.
 109
 110 `--disable-profile'
 111      Don't build libraries with profiling information.  You may want to
 112      use this option if you don't plan to do profiling.
 113
 114 `--enable-omitfp'
 115      Use maximum optimization for the normal (static and shared)
 116      libraries, and compile separate static libraries with debugging
 117      information and no optimisation.  We recommend against this.  The
 118      extra optimization doesn't gain you much, it may provoke compiler
 119      bugs, and you won't be able to trace bugs through the C library.
 120
 121 `--disable-versioning'
 122      Don't compile the shared libraries with symbol version information.
 123      Doing this will make the library that's built incompatible with old
 124      binaries, so it's not recommended.
 125
 126 `--enable-static-nss'
 127      Compile static versions of the NSS (Name Service Switch) libraries.
 128      This is not recommended because it defeats the purpose of NSS; a
 129      program linked statically with the NSS libraries cannot be
 130      dynamically reconfigured to use a different name database.
 131
 132 `--build=BUILD-SYSTEM'
 133 `--host=HOST-SYSTEM'
 134      These options are for cross-compiling.  If you give them both and
 135      BUILD-SYSTEM is different from HOST-SYSTEM, `configure' will
 136      prepare to cross-compile glibc from BUILD-SYSTEM to be used on
 137      HOST-SYSTEM.  You'll probably need the `--with-headers' option
 138      too, and you may have to override CONFIGURE's selection of the
 139      compiler and/or binutils.
 140
 141      If you give just `--host', configure will prepare for a native
 142      compile but use what you say instead of guessing what your system
 143      is.  This is most useful to change the CPU submodel.  For example,
 144      if configure guesses your machine as `i586-pc-linux-gnu' but you
 145      want to compile a library optimized for 386es, give
 146      `--host=i386-pc-linux-gnu' or just `--host=i386-linux'.  (A
 147      library compiled for a Pentium (`i586') will still work on a 386,
 148      but it may be slower.)
 149
 150      If you give just `--build', configure will get confused.
 151
 152    To build the library and related programs, type `make'.  This will
 153 produce a lot of output, some of which may look like errors from `make'
 154 but isn't.  Look for error messages from `make' containing `***'.
 155 Those indicate that something is really wrong.
 156
 157    The compilation process takes several hours even on fast hardware.
 158 Expect at least two hours for the default configuration on i586 for
 159 Linux.  For Hurd times are much longer.  Except for EGCS 1.1 (and later
 160 versions of EGCS), all supported versions of GCC have a problem which
 161 causes them to take several minutes to compile certain files in the
 162 iconvdata directory.  Do not panic if the compiler appears to hang.
 163
 164    If you want to run a parallel make, you can't just give `make' the
 165 `-j' option, because it won't be passed down to the sub-makes.
 166 Instead, edit the generated `Makefile' and uncomment the line
 167
 168      # PARALLELMFLAGS = -j 4
 169
 170 You can change the `4' to some other number as appropriate for your
 171 system.
 172
 173    To build and run some test programs which exercise some of the
 174 library facilities, type `make check'.  This should complete
 175 successfully; if it doesn't, do not use the built library, and report a
 176 bug.  *Note Reporting Bugs::, for how to do that.  Note that some of
 177 the tests assume they are not being run by `root'.  We recommend you
 178 compile and test glibc as an unprivileged user.
 179
 180    To format the `GNU C Library Reference Manual' for printing, type
 181 `make dvi'.  You need a working TeX installation to do this.  The
 182 distribution already includes the on-line formatted version of the
 183 manual, as Info files.  You can regenerate those with `make info', but
 184 it shouldn't be necessary.
 185
 186 Installing the C Library
 187 ========================
 188
 189    To install the library and its header files, and the Info files of
 190 the manual, type `make install'.  This will build things if necessary,
 191 before installing them.  Don't rely on that; compile everything first.
 192 If you are installing glibc as your primary C library, we recommend you
 193 shut the system down to single-user mode first, and reboot afterward.
 194 This minimizes the risk of breaking things when the library changes out
 195 from underneath.
 196
 197    If you are upgrading from a previous installation of glibc 2.0 or
 198 2.1, `make install' will do the entire job.  If you're upgrading from
 199 Linux libc5 or some other C library, you need to rename the old
 200 `/usr/include' directory out of the way before running `make install',
 201 or you will end up with a mixture of header files from both libraries,
 202 and you won't be able to compile anything.  You may also need to
 203 reconfigure GCC to work with the new library.  The easiest way to do
 204 that is to figure out the compiler switches to make it work again
 205 (`-Wl,-dynamic-linker=/lib/ld-linux.so.2' should work on Linux systems)
 206 and use them to recompile gcc.  You can also edit the specs file
 207 (`/usr/lib/gcc-lib/TARGET/VERSION/specs'), but that is a bit of a black
 208 art.
 209
 210    You can install glibc somewhere other than where you configured it
 211 to go by setting the `install_root' variable on the command line for
 212 `make install'.  The value of this variable is prepended to all the
 213 paths for installation.  This is useful when setting up a chroot
 214 environment or preparing a binary distribution.
 215
 216    Glibc 2.1 includes two daemons, `nscd' and `utmpd', which you may or
 217 may not want to run.  `nscd' caches name service lookups; it can
 218 dramatically improve performance with NIS+, and may help with DNS as
 219 well.  `utmpd' allows programs that use the old format for the `utmp'
 220 file to coexist with new programs.  For more information see the file
 221 `login/README.utmpd'.
 222
 223    One auxiliary program, `/usr/libexec/pt_chown', is installed setuid
 224 `root'.  This program is invoked by the `grantpt' function; it sets the
 225 permissions on a pseudoterminal so it can be used by the calling
 226 process.  This means programs like `xterm' and `screen' do not have to
 227 be setuid to get a pty.  (There may be other reasons why they need
 228 privileges.)  If you are using a 2.1 or newer Linux kernel with the
 229 `devptsfs' or `devfs' filesystems providing pty slaves, you don't need
 230 this program; otherwise you do.  The source for `pt_chown' is in
 231 `login/programs/pt_chown.c'.
 232
 233 Recommended Tools for Compilation
 234 =================================
 235
 236    We recommend installing the following GNU tools before attempting to
 237 build the GNU C library:
 238
 239    * GNU `make' 3.75
 240
 241      You need the latest version of GNU `make'.  Modifying the GNU C
 242      Library to work with other `make' programs would be so hard that we
 243      recommend you port GNU `make' instead.  *Really.*  We recommend
 244      version GNU `make' version 3.75 or 3.77.  All earlier versions
 245      have severe bugs or lack features. Version 3.76 is known to have
 246      bugs which only show up in big projects like GNU `libc'.  Version
 247      3.76.1 seems OK but some people have reported problems.
 248
 249    * EGCS 1.1.1, 1.1 or 1.0.3, or GCC 2.8.1
 250
 251      The GNU C library can only be compiled with the GNU C compiler
 252      family.  As of the 2.1 release, EGCS 1.0.3 or higher is required.
 253      GCC 2.8.1 can also be used (but see the FAQ for reasons why you
 254      might not want to).  Earlier versions simply are too buggy.
 255
 256      You can use whatever compiler you like to compile programs that
 257      use GNU libc, but be aware that both GCC 2.7 and 2.8 have bugs in
 258      their floating-point support that may be triggered by the math
 259      library.
 260
 261      On Alpha machines you need at least EGCS 1.1.1.  Earlier versions
 262      don't work reliably.
 263
 264      For PPC you might need some patches even on top of the last EGCS
 265      version.  See the FAQ.
 266
 267    * GNU `binutils' 2.9.1, 2.9.1.0.16, or later 2.9.1.0.x release
 268
 269      You must use GNU binutils (as and ld) if you want to build a shared
 270      library.  Even if you don't, we recommend you use them anyway.  No
 271      one has tested compilation with non-GNU binutils in a long time.
 272
 273      The quality of binutils releases has varied a bit recently.  The
 274      bugs are in obscure features, but glibc uses quite a few of those.
 275      2.9.1, 2.9.1.0.16, and later 2.9.1.0.x releases are known to
 276      work.  Versions after 2.8.1.0.23 may or may not work.  Older
 277      versions definitely don't.  2.9.1.0.16 or higher is required on
 278      some platforms, like PPC and Arm.
 279
 280      For PPC you might need some patches even on top of the last
 281      binutils version.  See the FAQ.
 282
 283    * GNU `texinfo' 3.12f
 284
 285      To correctly translate and install the Texinfo documentation you
 286      need this version of the `texinfo' package.  Earlier versions do
 287      not understand all the tags used in the document, and the
 288      installation mechanism for the info files is not present or works
 289      differently.
 290
 291    * GNU `awk' 3.0, or some other POSIX awk
 292
 293      Awk is used in several places to generate files.  The scripts
 294      should work with any POSIX-compliant awk implementation; `gawk'
 295      3.0 and `mawk' 1.3 are known to work.
 296
 297    * Perl 5
 298
 299      Perl is not required, but it is used if present to test the
 300      installation.  We may decide to use it elsewhere in the future.
 301
 302
 303 If you change any of the `configure.in' files you will also need
 304
 305    * GNU `autoconf' 2.12 or higher
 306
 307 and if you change any of the message translation files you will need
 308
 309    * GNU `gettext' 0.10.35 or later
 310
 311 You may also need these packages if you upgrade your source tree using
 312 patches, although we try to avoid this.
 313
 314 Supported Configurations
 315 ========================
 316
 317    The GNU C Library currently supports configurations that match the
 318 following patterns:
 319
 320      alpha-*-linux
 321      arm-*-linux
 322      arm-*-linuxaout
 323      arm-*-none
 324      iX86-*-gnu
 325      iX86-*-linux
 326      m68k-*-linux
 327      powerpc-*-linux
 328      sparc-*-linux
 329      sparc64-*-linux
 330
 331    Former releases of this library (version 1.09.1 and perhaps earlier
 332 versions) used to run on the following configurations:
 333
 334      alpha-dec-osf1
 335      alpha-*-linuxecoff
 336      iX86-*-bsd4.3
 337      iX86-*-isc2.2
 338      iX86-*-isc3.N
 339      iX86-*-sco3.2
 340      iX86-*-sco3.2v4
 341      iX86-*-sysv
 342      iX86-*-sysv4
 343      iX86-force_cpu386-none
 344      iX86-sequent-bsd
 345      i960-nindy960-none
 346      m68k-hp-bsd4.3
 347      m68k-mvme135-none
 348      m68k-mvme136-none
 349      m68k-sony-newsos3
 350      m68k-sony-newsos4
 351      m68k-sun-sunos4.N
 352      mips-dec-ultrix4.N
 353      mips-sgi-irix4.N
 354      sparc-sun-solaris2.N
 355      sparc-sun-sunos4.N
 356
 357    Since no one has volunteered to test and fix these configurations,
 358 they are not supported at the moment.  They probably don't compile;
 359 they definitely don't work anymore.  Porting the library is not hard.
 360 If you are interested in doing a port, please contact the glibc
 361 maintainers by sending electronic mail to <bug-glibc@gnu.org>.
 362
 363    Each case of `iX86' can be `i386', `i486', `i586', or `i686'.  All
 364 of those configurations produce a library that can run on any of these
 365 processors.  The library will be optimized for the specified processor,
 366 but will not use instructions not available on all of them.  If you
 367 want the library to use instructions only available on newer
 368 processors, give GCC the appropriate `-m' switches via CFLAGS.
 369
 370 Specific advice for Linux systems
 371 =================================
 372
 373    If you are installing GNU libc on a Linux system, you need to have
 374 the header files from a 2.2 kernel around for reference.  You do not
 375 need to use the 2.2 kernel, just have its headers where glibc can get
 376 at them.  The easiest way to do this is to unpack it in a directory
 377 such as `/usr/src/linux-2.2.1'.  In that directory, run `make config'
 378 and accept all the defaults.  Then run `make include/linux/version.h'.
 379 Finally, configure glibc with the option
 380 `--with-headers=/usr/src/linux-2.2.1/include'.  Use the most recent
 381 kernel you can get your hands on.
 382
 383    An alternate tactic is to unpack the 2.2 kernel and run `make
 384 config' as above.  Then rename or delete `/usr/include', create a new
 385 `/usr/include', and make the usual symbolic links of
 386 `/usr/include/linux' and `/usr/include/asm' into the 2.2 kernel
 387 sources.  You can then configure glibc with no special options.  This
 388 tactic is recommended if you are upgrading from libc5, since you need
 389 to get rid of the old header files anyway.
 390
 391    Note that `/usr/include/net' and `/usr/include/scsi' should *not* be
 392 symlinks into the kernel sources.  GNU libc provides its own versions
 393 of these files.
 394
 395    Linux expects some components of the libc installation to be in
 396 `/lib' and some in `/usr/lib'.  This is handled automatically if you
 397 configure glibc with `--prefix=/usr'.  If you set some other prefix or
 398 allow it to default to `/usr/local', then all the components are
 399 installed there.
 400
 401    If you are upgrading from libc5, you need to recompile every shared
 402 library on your system against the new library for the sake of new code,
 403 but keep the old libraries around for old binaries to use.  This is
 404 complicated and difficult.  Consult the Glibc2 HOWTO at
 405 <http://www.imaxx.net/~thrytis/glibc> for details.
 406
 407    You cannot use `nscd' with 2.0 kernels, due to bugs in the
 408 kernel-side thread support.  `nscd' happens to hit these bugs
 409 particularly hard, but you might have problems with any threaded
 410 program.
 411
 412 Reporting Bugs
 413 ==============
 414
 415    There are probably bugs in the GNU C library.  There are certainly
 416 errors and omissions in this manual.  If you report them, they will get
 417 fixed.  If you don't, no one will ever know about them and they will
 418 remain unfixed for all eternity, if not longer.
 419
 420    To report a bug, first you must find it.  Hopefully, this will be the
 421 hard part.  Once you've found a bug, make sure it's really a bug.  A
 422 good way to do this is to see if the GNU C library behaves the same way
 423 some other C library does.  If so, probably you are wrong and the
 424 libraries are right (but not necessarily).  If not, one of the libraries
 425 is probably wrong.  It might not be the GNU library.  Many historical
 426 Unix C libraries permit things that we don't, such as closing a file
 427 twice.
 428
 429    If you think you have found some way in which the GNU C library does
 430 not conform to the ISO and POSIX standards (*note Standards and
 431 Portability::.), that is definitely a bug.  Report it!
 432
 433    Once you're sure you've found a bug, try to narrow it down to the
 434 smallest test case that reproduces the problem.  In the case of a C
 435 library, you really only need to narrow it down to one library function
 436 call, if possible.  This should not be too difficult.
 437
 438    The final step when you have a simple test case is to report the bug.
 439 Do this using the `glibcbug' script.  It is installed with libc, or if
 440 you haven't installed it, will be in your build directory.  Send your
 441 test case, the results you got, the results you expected, and what you
 442 think the problem might be (if you've thought of anything).  `glibcbug'
 443 will insert the configuration information we need to see, and ship the
 444 report off to <bug-glibc@gnu.org>.  Don't send a message there
 445 directly; it is fed to a program that expects mail to be formatted in a
 446 particular way.  Use the script.
 447
 448    If you are not sure how a function should behave, and this manual
 449 doesn't tell you, that's a bug in the manual.  Report that too!  If the
 450 function's behavior disagrees with the manual, then either the library
 451 or the manual has a bug, so report the disagreement.  If you find any
 452 errors or omissions in this manual, please report them to the Internet
 453 address <bug-glibc-manual@gnu.org>.  If you refer to specific sections
 454 when reporting on the manual, please include the section names for
 455 easier identification.
 456