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:
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.
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. See section 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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