GNU Info
(libc.info)Configuring and compiling
Configuring and compiling GNU Libc
==================================
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 `/src/gnu/glibc-2.2.0', create a
directory `/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 `configure' found
at the top level of the source tree. In the scenario above, you'd type
$ ../glibc-2.2.0/configure ARGS...
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.
`configure' takes many options, but you can get away with knowing only
two: `--prefix' and `--enable-add-ons'. The `--prefix' option tells
configure where you want glibc installed. This defaults to
`/usr/local'. The `--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 CC and CFLAGS variables in the
environment when running `configure'. CC selects the C compiler that
will be used, and CFLAGS sets optimization options for the compiler.
The following list describes all of the available options for
`configure':
`--prefix=DIRECTORY'
Install machine-independent data files in subdirectories of
`DIRECTORY'. The default is to install in `/usr/local'.
`--exec-prefix=DIRECTORY'
Install the library and other machine-dependent files in
subdirectories of `DIRECTORY'. The default is to the `--prefix'
directory if that option is specified, or `/usr/local' otherwise.
`--with-headers=DIRECTORY'
Look for kernel header files in DIRECTORY, not `/usr/include'.
Glibc needs information from the kernel's private header files.
It will normally look in `/usr/include' for them, but if you
specify this option, it will look in DIRECTORY instead.
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'.
`--enable-add-ons[=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 _do_ want used, like this:
`--enable-add-ons=linuxthreads'
`--enable-kernel=VERSION'
This option is currently only useful on Linux systems. The
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 VERSION number is, the less
compatibility code is added, and the faster the code gets.
`--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. In that case, `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.
`--without-fp'
Use this option if your computer lacks hardware floating-point
support and your operating system does not emulate an FPU.
`--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.
`--disable-profile'
Don't build libraries with profiling information. You may want to
use this option if you don't plan to do profiling.
`--enable-omitfp'
Use maximum optimization for the normal (static and shared)
libraries, and compile separate static libraries with debugging
information and no optimization. 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.
`--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.
`--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.
`--build=BUILD-SYSTEM'
`--host=HOST-SYSTEM'
These options are for cross-compiling. If you specify both
options and BUILD-SYSTEM is different from HOST-SYSTEM, `configure'
will prepare to cross-compile glibc from BUILD-SYSTEM to be used
on HOST-SYSTEM. You'll probably need the `--with-headers' option
too, and you may have to override CONFIGURE's selection of the
compiler and/or binutils.
If you only specify `--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 `i586-pc-linux-gnu'
but you want to compile a library for 386es, give
`--host=i386-pc-linux-gnu' or just `--host=i386-linux' and add the
appropriate compiler flags (`-mcpu=i386' will do the trick) to
CFLAGS.
If you specify just `--build', configure will get confused.
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. 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 `make' the
`-j' option, because it won't be passed down to the sub-makes.
Instead, edit the generated `Makefile' and uncomment the line
# PARALLELMFLAGS = -j 4
You can change the `4' to some other number as appropriate for your
system. Instead of changing the `Makefile', you could give this option
directly to `make' and call it as, for example, `make
PARALLELMFLAGS=-j4'. If you're building in the source directory, you
must use the latter approach since in this case no new `Makefile' is
generated for you to change.
To build and run test programs which exercise some of the library
facilities, type `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. Note: Reporting Bugs, for instructions
on reporting bugs. Note that some of the tests assume they are not
being run by `root'. We recommend you compile and test glibc as an
unprivileged user.
To format the `GNU C Library Reference Manual' for printing, type
`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 `make info', but
it shouldn't be necessary.
The library has a number of special-purpose configuration parameters
which you can find in `Makeconfig'. These can be overwritten with the
file `configparms'. To change them, create a `configparms' in your
build directory and add values as appropriate for your system. The
file is included and parsed by `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 `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.
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