path: root/manual/install.texi

@c This is for making the `INSTALL' file for the distribution.
@c Makeinfo ignores it when processing the file from the include.
@setfilename INSTALL

@node Installation, Maintenance, Library Summary, Top
@c %MENU% How to install the GNU C library
@appendix Installing the GNU C Library

Before you do anything else, you should read the file @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.

Features can be added to GNU Libc via @dfn{add-on} bundles.  These are
separate tarfiles which you unpack into the top level of the source
tree.  Then you give @code{configure} the @samp{--enable-add-ons} option
to activate them, and they will be compiled into the library.  As of the
2.2 release, one important component of glibc is distributed as
``official'' add-ons: the linuxthreads add-on.  Unless you are doing an
unusual installation, you should get this.

Support for POSIX threads is maintained by someone else, so it's in a
separate package.  It is only available for Linux systems, but this will
change in the future.  Get it from the same place you got the main
bundle; the file is @file{glibc-linuxthreads-@var{VERSION}.tar.gz}.

You will need recent versions of several GNU tools: definitely GCC and
GNU Make, and possibly others.  @xref{Tools for Compilation}, below.

@menu
* Configuring and compiling::   How to compile and test GNU libc.
* Running make install::        How to install it once you've got it compiled.
* Tools for Compilation::       You'll need these first.
* Supported Configurations::    What it runs on, what it doesn't.
* Linux::                       Specific advice for Linux systems.
* Reporting Bugs::              So they'll get fixed.
@end menu

@node Configuring and compiling
@appendixsec Configuring and compiling GNU Libc
@cindex configuring
@cindex compiling

GNU libc can be compiled in the source directory, but we strongly advise to
build it in a separate build directory.  For example, if you have unpacked
the glibc sources in @file{/src/gnu/glibc-2.2.0}, create a directory
@file{/src/gnu/glibc-build} to put the object files in.  This allows
removing the whole build directory in case an error occurs, which is the
safest way to get a fresh start and should always be done.

From your object directory, run the shell script @file{configure} found
at the top level of the source tree.  In the scenario above, you'd type

@smallexample
$ ../glibc-2.2.0/configure @var{args...}
@end smallexample

Please note that even if you're building in a separate build directory,
the compilation needs to modify a few files in the source
directory, especially some files in the manual subdirectory.

@noindent
@code{configure} takes many options, but you can get away with knowing
only two: @samp{--prefix} and @samp{--enable-add-ons}.  The
@code{--prefix} option tells configure where you want glibc installed.
This defaults to @file{/usr/local}.  The @samp{--enable-add-ons} option
tells configure to use all the add-on bundles it finds in the source
directory.  Since important functionality is provided in add-ons, you
should always specify this option.

It may also be useful to set the @var{CC} and @var{CFLAGS} variables in
the environment when running @code{configure}.  @var{CC} selects the C
compiler that will be used, and @var{CFLAGS} sets optimization options
for the compiler.

The following list describes all of the available options for @code{configure}:

@table @samp
@item --prefix=@var{directory}
Install machine-independent data files in subdirectories of
@file{@var{directory}}.  The default is to install in @file{/usr/local}.

@item --exec-prefix=@var{directory}
Install the library and other machine-dependent files in subdirectories
of @file{@var{directory}}.  The default is to the @samp{--prefix}
directory if that option is specified, or @file{/usr/local} otherwise.

@item --with-headers=@var{directory}
Look for kernel header files in @var{directory}, not
@file{/usr/include}.  Glibc needs information from the kernel's private
header files.  It will normally look in @file{/usr/include} for them,
but if you specify this option, it will look in @var{DIRECTORY} instead.

This option is primarily of use on a system where the headers in
@file{/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
@file{/usr/include}.

@item --enable-add-ons[=@var{list}]
Enable add-on packages in your source tree.  If this option is specified
with no list, it enables all the add-on packages it finds.  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 @emph{do} want
used, like this: @samp{--enable-add-ons=linuxthreads}

@item --enable-kernel=@var{version}
This option is currently only useful on Linux systems.  The
@var{version} parameter should have the form X.Y.Z and describes the
smallest version of the Linux kernel the generated library is expected
to support.  The higher the @var{version} number is, the less
compatibility code is added, and the faster the code gets.

@item --with-binutils=@var{directory}
Use the binutils (assembler and linker) in @file{@var{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.  In that case, @code{configure} will detect the problem and
suppress these constructs, so that the library will still be usable, but
functionality may be lost---for example, you can't build a shared libc
with old binutils.

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

@c disable static doesn't work currently
@c @item --disable-static
@c Don't build static libraries.  Static libraries aren't that useful these
@c days, but we recommend you build them in case you need them.

@item --disable-shared
Don't build shared libraries even if it is possible.  Not all systems support
shared libraries; you need ELF support and (currently) the GNU linker.

@item --disable-profile
Don't build libraries with profiling information.  You may want to use
this option if you don't plan to do profiling.

@item --enable-omitfp
Use maximum optimization for the normal (static and shared)
libraries, and compile separate static libraries with debugging
information and no optimisation.  We recommend against this.  The extra
optimization doesn't gain you much, it may provoke compiler bugs, and
you won't be able to trace bugs through the C library.

@item --disable-versioning
Don't compile the shared libraries with symbol version information.
Doing this will make the resulting library incompatible with old
binaries, so it's not recommended.

@item --enable-static-nss
Compile static versions of the NSS (Name Service Switch) libraries.
This is not recommended because it defeats the purpose of NSS; a program
linked statically with the NSS libraries cannot be dynamically
reconfigured to use a different name database.

@item --build=@var{build-system}
@itemx --host=@var{host-system}
These options are for cross-compiling.  If you specify both options and
@var{build-system} is different from @var{host-system}, @code{configure}
will prepare to cross-compile glibc from @var{build-system} to be used
on @var{host-system}.  You'll probably need the @samp{--with-headers}
option too, and you may have to override @var{configure}'s selection of
the compiler and/or binutils.

If you only specify @samp{--host}, configure will prepare for a native
compile but use what you specify instead of guessing what your system is.
This is most useful to change the CPU submodel.  For example, if
configure guesses your machine as @code{i586-pc-linux-gnu} but you want
to compile a library for 386es, give @samp{--host=i386-pc-linux-gnu} or
just @samp{--host=i386-linux} and add the appropriate compiler flags
(@samp{-mcpu=i386} will do the trick) to @var{CFLAGS}.

If you specify just @samp{--build}, configure will get confused.
@end table

To build the library and related programs, type @code{make}.  This will
produce a lot of output, some of which may look like errors from
@code{make} but isn't.  Look for error messages from @code{make}
containing @samp{***}.  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.  Except for EGCS 1.1 and GCC
2.95 (and later versions of GCC), all supported versions 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.

If you want to run a parallel make, you can't just give @code{make} the
@samp{-j} option, because it won't be passed down to the sub-makes.
Instead, edit the generated @file{Makefile} and uncomment the line

@smallexample
# PARALLELMFLAGS = -j 4
@end smallexample

@noindent
You can change the @samp{4} to some other number as appropriate for
your system.  Instead of changing the @file{Makefile}, you could give
this option directly to @code{make} and call it as, for example,
@code{make PARALLELMFLAGS=-j4}.  If you're building in the source
directory, you must use the latter approach since in this case no
new @file{Makefile} is generated for you to change.

To build and run test programs which exercise some of the library
facilities, type @code{make check}.  If it does not complete
successfully, do not use the built library, and report a bug after
verifying that the problem is not already known.  @xref{Reporting Bugs},
for instructions on reporting bugs.  Note that some of the tests assume
they are not being run by @code{root}.  We recommend you compile and
test glibc as an unprivileged user.

To format the @cite{GNU C Library Reference Manual} for printing, type
@w{@code{make dvi}}.  You need a working @TeX{} installation to do this.
The distribution already includes the on-line formatted version of the
manual, as Info files.  You can regenerate those with @w{@code{make
info}}, but it shouldn't be necessary.

The library has a number of special-purpose configuration parameters
which you can find in @file{Makeconfig}.  These can be overwritten with
the file @file{configparms}.  To change them, create a
@file{configparms} in your build directory and add values as appropriate
for your system.  The file is included and parsed by @code{make} and has
to follow the conventions for makefiles.

It is easy to configure the GNU C library for cross-compilation by
setting a few variables in @file{configparms}.  Set @code{CC} to the
cross-compiler for the target you configured the library for; it is
important to use this same @code{CC} value when running
@code{configure}, like this: @samp{CC=@var{target}-gcc configure
@var{target}}.  Set @code{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 @code{AR} and @code{RANLIB} to cross-compiling versions
of @code{ar} and @code{ranlib} if the native tools are not configured to
work with object files for the target you configured for.


@node Running make install
@appendixsec Installing the C Library
@cindex installing

To install the library and its header files, and the Info files of the
manual, type @code{make install}.  This will build things if necessary,
before installing them.  However, you should still compile everything first.
If you are installing glibc as your primary C library, we recommend that you
shut the system down to single-user mode first, and reboot afterward.
This minimizes the risk of breaking things when the library changes out
from underneath.

If you're upgrading from Linux libc5 or some other C library, you need to
replace the @file{/usr/include} with a fresh directory before installing it.
The new @file{/usr/include} should contain the Linux headers, but nothing else.

You must first build the library (@samp{make}), optionally check it
(@samp{make check}), switch the include directories and then install
(@samp{make install}).  The steps must be done in this order.  Not moving
the directory before install will result in an unusable mixture of header
files from both libraries, but configuring, building, and checking the
library requires the ability to compile and run programs against the old
library.

If you are upgrading from a previous installation of glibc 2.0 or 2.1,
@samp{make install} will do the entire job.  You do not need to remove
the old includes -- if you want to do so anyway you must then follow the
order given above.

You may also need to reconfigure GCC to work with the new library.  The
easiest way to do that is to figure out the compiler switches to make it
work again (@samp{-Wl,--dynamic-linker=/lib/ld-linux.so.2} should work on
Linux systems) and use them to recompile gcc.  You can also edit the specs
file (@file{/usr/lib/gcc-lib/@var{TARGET}/@var{VERSION}/specs}), but that
is a bit of a black art.

You can install glibc somewhere other than where you configured it to go
by setting the @code{install_root} variable on the command line for
@samp{make install}.  The value of this variable is prepended to all the
paths for installation.  This is useful when setting up a chroot
environment or preparing a binary distribution.  The directory should be
specified with an absolute file name.

Glibc 2.2 includes a daemon called @code{nscd}, which you
may or may not want to run.  @code{nscd} caches name service lookups; it
can dramatically improve performance with NIS+, and may help with DNS as
well.

One auxiliary program, @file{/usr/libexec/pt_chown}, is installed setuid
@code{root}.  This program is invoked by the @code{grantpt} function; it
sets the permissions on a pseudoterminal so it can be used by the
calling process.  This means programs like @code{xterm} and
@code{screen} do not have to be setuid to get a pty.  (There may be
other reasons why they need privileges.)  If you are using a 2.1 or
newer Linux kernel with the @code{devptsfs} or @code{devfs} filesystems
providing pty slaves, you don't need this program; otherwise you do.
The source for @file{pt_chown} is in @file{login/programs/pt_chown.c}.

After installation you might want to configure the timezone and locale
installation of your system.  The GNU C library comes with a locale
database which gets configured with @code{localedef}.  For example, to
set up a German locale with name @code{de_DE}, simply issue the command
@samp{localedef -i de_DE -f ISO-8859-1 de_DE}.  To configure all locales
that are supported by glibc, you can issue from your build directory the
command @samp{make localedata/install-locales}.

To configure the locally used timezone, you can either set the @code{TZ}
environment variable.  The script @code{tzselect} helps you to select
the right value.  As an example for Germany, tzselect would tell you to
use @samp{TZ='Europe/Berlin'}.  For a system wide installation (the
given paths are for an installation with @samp{--prefix=/usr}), link the
timezone file which is in @file{/usr/share/zoneinfo} to the file
@file{/etc/localtime}.  For Germany, you might execute @samp{ln -s
/usr/share/zoneinfo/Europe/Berlin /etc/localtime}.

@node Tools for Compilation
@appendixsec Recommended Tools for Compilation
@cindex installation tools
@cindex tools, for installing library

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

@itemize @bullet
@item
GNU @code{make} 3.79 or newer

You need the latest version of GNU @code{make}.  Modifying the GNU C
Library to work with other @code{make} programs would be so difficult that we
recommend you port GNU @code{make} instead.  @strong{Really.}  We
recommend version GNU @code{make} version 3.79.  All earlier
versions have severe bugs or lack features.

@item
EGCS 1.1.1, 1.1 or 1.0.3, or GCC 2.8.1, 2.95 or newer

The GNU C library can only be compiled with the GNU C compiler family.
As of the 2.1 release, EGCS 1.0.3 or higher is required.  GCC 2.8.1 can
also be used (but see the FAQ for reasons why you might not want to).
Earlier versions simply are too buggy.  As of this writing, GCC 2.95.2
is the compiler we advise to use.

You can use whatever compiler you like to compile programs that use GNU
libc, but be aware that both GCC 2.7 and 2.8 have bugs in their
floating-point support that may be triggered by the math library.

On Alpha machines you need at least EGCS 1.1.1.  Earlier versions don't
work reliably.

For PPC you might need some patches even on top of the last EGCS version.
See the FAQ.

@item
GNU @code{binutils} 2.9.1, 2.9.1.0.16, or later 2.9.1.0.x release

You must use GNU binutils (as and ld) if you want to build a shared
library.  Even if you don't, we recommend you use them anyway.