How to Install the GNU C Library

Installation of the GNU C library is relatively simple, but usually requires several GNU tools to be installed already. (see section Recommended Tools to Install the GNU C Library, below.)

To configure the GNU C library for your system, run the shell script `configure' with sh. Use an argument which is the conventional GNU name for your system configuration--for example, `sparc-sun-sunos4.1', for a Sun 4 running SunOS 4.1. See section `Installing GNU CC' in Using and Porting GNU CC, 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 its 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-gnu-ld'

Use this option if you plan to use GNU ld to link programs with the GNU C Library. (We strongly recommend that you do.) This option enables use of features that exist only in GNU ld; so if you configure for GNU ld you must use GNU ld every time you link with the GNU C Library, and when building it.

`--with-gnu-as'

Use this option if you plan to use the GNU assembler, gas, when building the GNU C Library. On some systems, the library may not build properly if you do not use gas.

`--with-gnu-binutils'

This option implies both `--with-gnu-ld' and `--with-gnu-as'. On systems where GNU tools are the system tools, there is no need to specify this option. These include GNU, GNU/Linux, and free BSD systems.

`--without-fp'

`--nfp'

Use this option if your computer lacks hardware floating-point support.

`--prefix=directory'

Install machine-independent data files in subdirectories of `directory'. (You can also set this in `configparms'; see below.)

`--exec-prefix=directory'

Install the library and other machine-dependent files in subdirectories of `directory'. (You can also set this in `configparms'; see below.)

`--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 static 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'.

The simplest way to run configure is to do it in the directory that contains the library sources. This prepares to build the library in that very directory.

You can prepare to build the library in some other directory by going to that other directory to run configure. In order to run configure, you will have to specify a directory for it, like this:

mkdir sun4
cd sun4
../configure sparc-sun-sunos4.1

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 `Makeconfig'; see the comments in that file for the details.

But don't edit the file `Makeconfig' yourself--instead, create a file `configparms' in the directory where you are building the library, and define in that file the parameters you want to specify. `configparms' should not be an edited copy of `Makeconfig'; specify only the parameters that you want to override. To see how to set these parameters, find the section of `Makeconfig' that says "These are the configuration variables." Then for each parameter that you want to change, copy the definition from `Makeconfig' to your new `configparms' file, and change the value as appropriate for your system.

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.

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.

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