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Installing the GNU C Library
****************************

   Installation of the GNU C library is relatively simple, but usually
requires several GNU tools to be installed already.

   Before you do anything else, you should read the file `FAQ' found at
the top level of the source tree.  This file answers common questions
and describes problems you may experience with compilation and
installation.  It is updated more frequently than this manual.

   To configure the GNU C library for your system, run the shell script
`configure' with `sh'.  You might use an argument which is the
conventional GNU name for your system configuration--for example,
`i486-pc-linux-gnu', for Linux running on i486.  *Note Installation:
(gcc.info)Installation, for a full description of standard GNU
configuration names.  If you omit the configuration name, `configure'
will try to guess one for you by inspecting the system it is running
on.  It may or may not be able to come up with a guess, and the guess
might be wrong.  `configure' will tell you the canonical name of the
chosen configuration before proceeding.

   Here are some options that you should specify (if appropriate) when
you run `configure':

`--with-binutils=DIRECTORY'
     Use the binutils (assembler and linker) in `DIRECTORY', not the
     ones the C compiler would default to.  You could use this option if
     the default binutils on your system cannot deal with all the
     constructs in the GNU C library.  (`configure' will detect the
     problem and suppress these constructs, so the library will still
     be usable, but functionality may be lost--for example, you can not
     build a shared libc with old binutils.)

`--without-fp'
`--nfp'
     Use this option if your computer lacks hardware floating-point
     support and your operating system does not emulate an FPU.

`--prefix=DIRECTORY'
     Install machine-independent data files in subdirectories of
     `DIRECTORY'.  (You can also set this in `configparms'; see below.)
     The default is to install in `/usr/local'.

`--exec-prefix=DIRECTORY'
     Install the library and other machine-dependent files in
     subdirectories of `DIRECTORY'.  (You can also set this in
     `configparms'; see below.)  The default is to use <prefix>/bin and
     <prefix>/sbin.

`--enable-shared'
`--disable-shared'
     Enable or disable building of an ELF shared library on systems that
     support it.  The default is to build the shared library on systems
     using ELF when the GNU `binutils' are available.

`--enable-profile'
`--disable-profile'
     Enable or disable building of the profiled C library, `-lc_p'.  The
     default is to build the profiled library.  You may wish to disable
     it if you don't plan to do profiling, because it doubles the build
     time of compiling just the unprofiled static library.

`--enable-omitfp'
     Enable building a highly-optimized but possibly undebuggable C
     library.  This causes the normal static and shared (if enabled) C
     libraries to be compiled with maximal optimization, including the
     `-fomit-frame-pointer' switch that makes debugging impossible on
     many machines, and without debugging information (which makes the
     binaries substantially smaller).  An additional static library is
     compiled with no optimization and full debugging information, and
     installed as `-lc_g'.

`--enable-add-ons[=LIST]'
     Certain components of the C library are distributed separately
     from the rest of the sources.  In particular, the `crypt' function
     and its friends are separated due to US export control
     regulations, and the threading support code for Linux is
     maintained separately.  You can get these "add-on" packages from
     the same place you got the libc sources.  To use them, unpack them
     into your source tree, and give `configure' the `--enable-add-ons'
     option.

     If you do not wish to use some add-on package that you have
     present in your source tree, give this option a list of the
     add-ons that you *do* want used, like this:
     `--enable-add-ons=crypt,linuxthreads'

`--with-headers=DIRECTORY'
     Search only DIRECTORY and the C compiler's private directory for
     header files not found in the libc sources.  `/usr/include' will
     not be searched if this option is given.  On Linux, DIRECTORY
     should be the kernel's private include directory (usually
     `/usr/src/linux/include').

     This option is primarily of use on a system where the headers in
     `/usr/include' come from an older version of glibc.  Conflicts can
     occasionally happen in this case.  Note that Linux libc5 qualifies
     as an older version of glibc.  You can also use this option if you
     want to compile glibc with a newer set of kernel headers than the
     ones found in `/usr/include'.

   You should not build the library in the same directory as the
sources, because there are bugs in `make clean'.  Make a directory for
the build, and run `configure' from that directory, like this:

     mkdir linux
     cd linux
     ../configure

`configure' looks for the sources in whatever directory you specified
for finding `configure' itself.  It does not matter where in the file
system the source and build directories are--as long as you specify the
source directory when you run `configure', you will get the proper
results.

   This feature lets you keep sources and binaries in different
directories, and that makes it easy to build the library for several
different machines from the same set of sources.  Simply create a build
directory for each target machine, and run `configure' in that
directory specifying the target machine's configuration name.

   The library has a number of special-purpose configuration parameters.
These are defined in the file `configparms'; see the comments in that
file for the details.  To change them, copy `configparms' into your
build directory and modify it as appropriate for your system.
`configure' will not notice your modifications if you change the file
in the source directory.

   It is easy to configure the GNU C library for cross-compilation by
setting a few variables in `configparms'.  Set `CC' to the
cross-compiler for the target you configured the library for; it is
important to use this same `CC' value when running `configure', like
this: `CC=TARGET-gcc configure TARGET'.  Set `BUILD_CC' to the compiler
to use for for programs run on the build system as part of compiling
the library.  You may need to set `AR' and `RANLIB' to cross-compiling
versions of `ar' and `ranlib' if the native tools are not configured to
work with object files for the target you configured for.

   Some of the machine-dependent code for some machines uses extensions
in the GNU C compiler, so you may need to compile the library with GCC.
(In fact, all of the existing complete ports require GCC.)

   To build the library and related programs, type `make'.  This will
produce a lot of output, some of which may look like errors from `make'
(but isn't).  Look for error messages from `make' containing `***'.
Those indicate that something is really wrong.

   The compilation process takes several hours even on fast hardware;
expect at least two hours for the default configuration on i586 for
Linux.  For Hurd times are much longer.  All current releases of GCC
have a problem which causes them to take several minutes to compile
certain files in the iconvdata directory.  Do not panic if the compiler
appears to hang.

   To build and run some test programs which exercise some of the
library facilities, type `make check'.  This will produce several files
with names like `PROGRAM.out'.

   To format the `GNU C Library Reference Manual' for printing, type
`make dvi'.  You need a working TeX installation to do this.

   To install the library and its header files, and the Info files of
the manual, type `make install'.  This will build things if necessary,
before installing them.  If you want to install the files in a different
place than the one specified at configuration time you can specify a
value for the Makefile variable `install_root' on the command line.
This is useful to create chroot'ed environment or to prepare binary
releases.

   For now (in this alpha version, and at least on RedHat Linux), if you
are trying to install this as your default libraries, a different
installation method is recommended.  Move `/usr/include' out of the
way, create a new `/usr/include' directory (don't forget the symlinks
`/usr/include/asm' and `/usr/include/linux', that should point to
`/usr/src/linux/include/asm' and `/usr/src/linux/include/linux' -or
wherever you keep your kernel sources-respectively), build normally and
install into somewhere else via `install_root'. Then move your
`/usr/include' back, and copy the newly created stuff by hand over the
old. Remember to copy programs and shared libraries into `FILENAME.new'
and then move `FILENAME.new' to `FILENAME', as the files might be in
use. You will have to `ranlib' your copies of the static libraries
`/usr/lib/libNAME.a'. You will see that `libbsd-compat.a', `libieee.a',
and `libmcheck.a' are just object files, not archives. This is normal.
Copy the new header files over the old ones by something like
`cd /usr; (cd INSTALL_ROOT; tar cf - include) | tar xf -'.

Recommended Tools to Install the GNU C Library
==============================================

   We recommend installing the following GNU tools before attempting to
build the GNU C library:

   * GNU `make' 3.75

     You need the latest version of GNU `make'.  Modifying the GNU C
     Library to work with other `make' programs would be so hard that we
     recommend you port GNU `make' instead.  *Really.*  We recommend
     version GNU `make' version 3.75.  Versions 3.76 and 3.76.1 are
     known to have bugs which only show up in big projects like GNU
     `libc'.

   * GCC 2.8.1/EGCS 1.0.2

     On most platforms, the GNU C library can only be compiled with the
     GNU C compiler family.  We recommend GCC version 2.8.1 and EGCS
     version 1.0.2 or later versions of these two; earlier versions may
     have problems.

   * GNU `binutils' 2.8.1.0.23

     Using the GNU `binutils' (assembler, linker, and related tools) is
     preferable when possible, and they are required to build an ELF
     shared C library.  Version 2.1 of the library uses ELF symbol
     versioning extensively.  Support for this feature is incomplete or
     buggy before binutils 2.8.1.0.23, so you must use at least this
     version.

   * GNU `texinfo' 3.11

     To correctly translate and install the Texinfo documentation you
     need this version of the `texinfo' package.  Earlier versions do
     not understand all the tags used in the document, and the
     installation mechanisms for the info files is not present or works
     differently.

     On some Debian Linux based systems the `install-info' program
     supplied with the system works differently from the one we expect.
     You must therefore run `make install' like this:

          make INSTALL_INFO=/path/to/GNU/install-info install

   * GNU `awk' 3.0

     Several files used during the build are generated using features
     of GNU `awk' that are not found in other implementations.

If you change any of the `configure.in' files you will also need

   * GNU `autoconf' 2.12

and if you change any of the message translation files you will need

   * GNU `gettext' 0.10 or later

You may also need these packages if you upgrade your source tree using
patches, although we try to avoid this.

Supported Configurations
========================

   The GNU C Library currently supports configurations that match the
following patterns:

     alpha-ANYTHING-linux
     arm-ANYTHING-linuxaout
     arm-ANYTHING-none
     iX86-ANYTHING-gnu
     iX86-ANYTHING-linux
     m68k-ANYTHING-linux
     powerpc-ANYTHING-linux
     sparc-ANYTHING-linux
     sparc64-ANYTHING-linux

   Former releases of this library (version 1.09.1 and perhaps earlier
versions) used to run on the following configurations:

     alpha-dec-osf1
     alpha-ANYTHING-linuxecoff
     iX86-ANYTHING-bsd4.3
     iX86-ANYTHING-isc2.2
     iX86-ANYTHING-isc3.N
     iX86-ANYTHING-sco3.2
     iX86-ANYTHING-sco3.2v4
     iX86-ANYTHING-sysv
     iX86-ANYTHING-sysv4
     iX86-force_cpu386-none
     iX86-sequent-bsd
     i960-nindy960-none
     m68k-hp-bsd4.3
     m68k-mvme135-none
     m68k-mvme136-none
     m68k-sony-newsos3
     m68k-sony-newsos4
     m68k-sun-sunos4.N
     mips-dec-ultrix4.N
     mips-sgi-irix4.N
     sparc-sun-solaris2.N
     sparc-sun-sunos4.N

   Since no one has volunteered to test and fix these configurations,
they are not supported at the moment.  They probably don't compile;
they definitely don't work anymore.  Porting the library is not hard.
If you are interested in doing a port, please contact the glibc
maintainers by sending electronic mail to <bug-glibc@gnu.org>.

   Each case of `iX86' can be `i386', `i486', `i586', or `i686'.  All
of those configurations produce a library that can run on any of these
processors.  The library will be optimized for the specified processor,
but will not use instructions not available on all of them.

   While no other configurations are supported, there are handy aliases
for these few.  (These aliases work in other GNU software as well.)

     decstation
     hp320-bsd4.3 hp300bsd
     i486-gnu
     i586-linux
     i386-sco
     i386-sco3.2v4
     i386-sequent-dynix
     i386-svr4
     news
     sun3-sunos4.N sun3
     sun4-solaris2.N sun4-sunos5.N
     sun4-sunos4.N sun4

Useful hints for the installation
=================================

   There are a some more or less obvious methods one should know when
compiling GNU libc:

   * Better never compile in the source directory.  Create a new
     directory and run the `configure' from there.  Everything should
     happen automagically.

   * You can use the `-j' option of GNU make by changing the line
     specifying `PARALLELMAKE' in the Makefile generated during the
     configuration.

     It is not useful to start the `make' process using the `-j' option
     since this option is not propagated down to the sub-`make's.

   * If you made some changes after a complete build and only want to
     check these changes run `make' while specifying the list of
     subdirs it has to visit.

          make subdirs="nss elf"

     The above build run will only visit the subdirectories `nss' and
     `elf'.  Beside this it updates the `libc' files itself.

Reporting Bugs
==============

   There are probably bugs in the GNU C library.  There are certainly
errors and omissions in this manual.  If you report them, they will get
fixed.  If you don't, no one will ever know about them and they will
remain unfixed for all eternity, if not longer.

   To report a bug, first you must find it.  Hopefully, this will be the
hard part.  Once you've found a bug, make sure it's really a bug.  A
good way to do this is to see if the GNU C library behaves the same way
some other C library does.  If so, probably you are wrong and the
libraries are right (but not necessarily).  If not, one of the libraries
is probably wrong.

   Once you're sure you've found a bug, try to narrow it down to the
smallest test case that reproduces the problem.  In the case of a C
library, you really only need to narrow it down to one library function
call, if possible.  This should not be too difficult.

   The final step when you have a simple test case is to report the bug.
When reporting a bug, send your test case, the results you got, the
results you expected, what you think the problem might be (if you've
thought of anything), your system type, and the version of the GNU C
library which you are using.  Also include the files `config.status'
and `config.make' which are created by running `configure'; they will
be in whatever directory was current when you ran `configure'.

   If you think you have found some way in which the GNU C library does
not conform to the ISO and POSIX standards (*note Standards and
Portability::.), that is definitely a bug.  Report it!

   Send bug reports to the Internet address <bug-glibc@gnu.org> using
the `glibcbug' script which is installed by the GNU C library.  If you
have other problems with installation or use, please report those as
well.

   If you are not sure how a function should behave, and this manual
doesn't tell you, that's a bug in the manual.  Report that too!  If the
function's behavior disagrees with the manual, then either the library
or the manual has a bug, so report the disagreement.  If you find any
errors or omissions in this manual, please report them to the Internet
address <bug-glibc-manual@gnu.org>.  If you refer to specific sections
when reporting on the manual, please include the section names for
easier identification.