Glibc 2 HOWTO

Glibc 2 HOWTO
Eric Green, [email protected]
v1.6, 22 June 1998

The glibc 2 HOWTO covers installing and using the GNU C Library ver-
sion 2 (libc 6) on Linux systems.
______________________________________________________________________

Table of Contents

1. Introduction.

1.1 About glibc 2.
1.2 About this document.
1.3 Recent changes in this document.

2. Choosing your installation method.

3. Getting the library.

4. Installing as a test library.

4.1 Compiling and installing.
4.1.1 Prerequisites.
4.1.2 Extracting the source.
4.1.3 Configuring.
4.1.4 Compiling and installing.
4.2 Updating the dynamic loader.
4.3 Configuring for gcc.
4.4 Updating header file links.
4.5 Testing your installation.

5. Installing as the primary C library.

5.1 Building the library from source.
5.1.1 Prerequisites.
5.1.2 Extracting the source.
5.1.3 Configuring.
5.1.4 Compiling.
5.2 Preparing for installation.
5.3 Installing from the binary package.
5.4 Installing from the source.
5.5 Updating the gcc specs.
5.6 Testing your installation.

6. Compiling with the non-primary libc.

6.1 A warning when using non-primary libcs.
6.2 Compiling programs with a test glibc.
6.3 Compiling programs with libc 5 when glibc is primary library.

7. Compiling C++ programs.

7.1 Installing libg++ for a test glibc install.
7.2 Installing libg++ for a primary glibc install.
7.3 Compiling C++ programs with the non-primary libc.

8. Problems.

8.1 Host names do not resolve.

9. Reporting bugs.

10. Sample specs file.

11. Miscellanea.

11.1 Further information.
11.1.1 Web pages.
11.1.2 Newgroups.
11.1.3 Mailing lists.
11.2 Credits.
11.3 Feedback.
11.4 Copyright.

______________________________________________________________________

1. Introduction.

1.1. About glibc 2.

Glibc 2 is the latest version of the GNU C Library. It currently runs
unmodified on GNU Hurd systems and Linux i386, m68k, and alpha
systems. Support for Linux PowerPC, MIPS, Sparc, Sparc 64, and Arm
will be in version 2.1. In the future support for other architectures
and operating systems will be added.

On Linux, glibc 2 is used as the libc with major version 6, the
successor of the Linux libc 5. It is intended by the Linux libc
developers to eventually replace libc 5. As of 2.0.6, glibc is
considered production quality. Version 2.1 (due out in the near
future) will be ready for main stream use along with adding more ports
and features.

There are three optional add-ons available for glibc 2:

Crypt
The UFC-crypt package. It is seperate because of export
restrictions.

LinuxThreads
An implementation of the Posix 1003.1c "pthread" interface.

Locale data
Contains the data needed to build the locale data files to use
the internationalization features of the glibc.

The crypt and LinuxThreads add-ons are strongly recommended... not
using them risks to be incompatible with the libraries of other
systems. (If you do not wish to use them, you must add the option
--disable-sanity-checks when you run configure.)

1.2. About this document.

This HOWTO covers installing the glibc 2 library on an existing Linux
system. It is tailored for users of Intel based systems currently
using libc 5, but users of other systems and alternate libraries (such
as glibc 1) should be able to use this information by substituting the
proper filenames and architecture names in the appropriate places.

The latest copy of this HOWTO can be found as part of the Linux
Documentation Project <http://sunsite.unc.edu/LDP> or from
<http://www.imaxx.net/~thrytis/glibc/Glibc2-HOWTO.html>.

1.3. Recent changes in this document.

Differences between version 1.6 and 1.5:

o Fixed the install instructions of the binary glibc package.

Differences between version 1.5 and 1.4:

o Indexing added Ed Bailey.

o Changed my email address.

2. Choosing your installation method.

There are a few ways to install glibc. You can install the libraries
as a test, using the existing libraries as the default but letting you
try the new libraries by using different options when compiling your
program. Installing in this way also makes it easy to remove glibc in
the future (though any program linked with glibc will no longer work
after the libraries are removed). Using glibc as a test library
requires you to compile the libraries from source. There is no binary
distribution for installing libraries this way. This installation is
described in ``Installing as a test library''.

The other way described in this document to install is using glibc as
your primary library. All new programs that you compile on your
system will use glibc, though you can link programs with your old
libraries using different options while compiling. You can either
install the libraries from binaries, or compile the library yourself.
If you want to change optimization or configuration options, or use an
add-on which is not distributed as a binary package, you must get the
source distribution and compile. This installation procedure is
described in ``Installing as the primary C library''.

Frodo Looijaard describes yet another way of installing glibc. His
method involves installing glibc as a secondary library and setting up
a cross compiler to compile using glibc. The installation procedure
for this method is more complicated then the test library install
described in this document, but allows for easier compiling when
linking to glibc. This method is described in his Installing glibc-2
on Linux <http://huizen.dds.nl/~frodol/glibc/> document.

If you are currently running Debian 1.3 but do not want to upgrade to
the unstable version of Debian to use glibc, the Debian libc5 to libc6
Mini-HOWTO <http://www.gate.net/~storm/FAQ/libc5-libc6-Mini-
HOWTO.html> describes how to use Debian packages to upgrade your
system.

If you are installing glibc 2 on an important system, you might want
to use the test install. Even if there are no bugs, some programs
will need to be modified before they will compile due to changes in
function prototypes and types.

3. Getting the library.

The glibc 2 consists of the glibc package and three optional add-on
packages, LinuxThreads, Locale, and Crypt. The source can be found at

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-2.0.6.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-linuxthreads-2.0.6.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-localedata-2.0.6.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-crypt-2.0.6.tar.gz>

It will take about 150 MB of disk space for the full compile and
install. The basic binary install of just the core library package is
about 50 MB.

Binary packages for 2.0.6 are not available. Version 2.0.4 binary
packages are available for i386 and m68k, and version 2.0.1 for the
alpha can be found at

o Intel x86:

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-2.0.4.bin.i386.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-crypt-2.0.4.bin.i386.tar.gz>

o Alpha:

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-2.0.1.bin.alpha-linux.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-crypt-2.0.1.bin.alpha-
linux.tar.gz>

o m68k:

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-2.0.4-m68k-linux.bin.tar.gz>

o <ftp://prep.ai.mit.edu/pub/gnu/glibc-crypt-2.0.4-m68k-
linux.bin.tar.gz>

There are export restrictions on the crypt add-on. Non-US users
should get it from <ftp://ftp.ifi.uio.no/pub/gnu>.

If you are running a Red Hat distribution, you can get rpms for glibc
2 from <ftp://ftp.redhat.com/pub/redhat/>. Glibc 2 is the primary C
library for the new Red Hat distribution 5.0.

If you are running a Debian distribution, you can get the packages for
glibc 2 from <ftp://ftp.debian.org/debian/dists/unstable/main/>. The
files are named libc6. Glibc 2 is now part of the base package of the
hamm version of Debian, and will be the primary libc when Debian 2.0
is released.

4. Installing as a test library.

This section covers installing glibc 2 as a test library. Anything
you compile will be linked to your existing libraries unless you give
some extra parameters to link to the new libraries. It appears that
the paths are compiled into quite a few files, so you probably have to
install the library from source.

4.1. Compiling and installing.

4.1.1. Prerequisites.

o About 150 MB free disk space

o GNU make 3.75

o gcc >= 2.7.2 (better 2.7.2.1)

o binutils 2.8.1 (for alpha you need a snapshot)

o bash 2.0

o autoconf 2.12 (if you change configure.in)

o texinfo 3.11

On an i586@133 with 64 MB of RAM, it takes about 3 hours to compile
with full libraries with add-ons. On a loaded i686@200, it takes
about half an hour.

4.1.2. Extracting the source.

You need to extract the source from the archives so you can compile
it. The best way to do this is:

tar xzf glibc-2.0.6.tar.gz
cd glibc-2.0.6
tar xzf ../glibc-linuxthreads-2.0.6.tar.gz
tar xzf ../glibc-crypt-2.0.6.tar.gz
tar xzf ../glibc-localedata-2.0.6.tar.gz

This will put linuxthreads, crypt, and localedata directories in the
glibc-2.0.6 directory where configure can find these add-ons.

4.1.3. Configuring.

In the glibc-2.0.6 directory, create a directory named compile, and cd
into it. All work will be done in this directory, which will simplify
cleaning up. (The developers have not been very concerned with
getting 'make clean' perfect yet.)

mkdir compile
cd compile

Run ../configure. To use the add-on packages, you need to specify
them with --enable-add-ons, such as --enable-add-ons=linux-
threads,crypt,localedata. You also need to choose a destination
directory to install to. /usr/i486-linuxglibc2 is a good choice. The
configure line for this would be:

../configure --enable-add-ons=linuxthreads,crypt,localedata --prefix=/usr/i486-linuxglibc2

4.1.4. Compiling and installing.

To compile and verify, run:

make
make check

If the 'make check' succeeds, install the library as root (while still
in the compile/ directory):

make install

4.2. Updating the dynamic loader.

1. Create a link from the new ld.so to /lib/ld-linux.so.2:

ln -s /usr/i486-linuxglibc2/lib/ld-linux.so.2 /lib/ld-linux.so.2

This is the only library where the location is fixed once a program is
linked, and using a link in /lib will ease upgrading to glibc as your
primary C library when the stable version is released.

2. Edit /etc/ld.so.conf. You need to add path to the lib directory
the new libraries reside in at the end of the file, which will be
<prefix>/lib, such as /usr/i486-linuxglibc2/lib for the choice
above. After you have modified /etc/ld.so.conf, run

ldconfig -v

4.3. Configuring for gcc.

The last step of installation is updating /usr/lib/gcc-lib so gcc
knows how to use the new libraries. First you need to duplicate the
existing configuration. To find out which configuration is current,
use the -v option of gcc:

% gcc -v
Reading specs from /usr/lib/gcc-lib/i486-unknown-linux/2.7.2.2/specs
gcc version 2.7.2.2

In this case, i486-unknown-linux is the system, and 2.7.2.2 is the
version. You need to copy the /usr/lib/gcc-lib/<system> to the new
test system directory:

cd /usr/lib/gcc-lib/
cp -r i486-unknown-linux i486-linuxglibc2

Change into your new test system directory and version directory

cd /usr/lib/gcc-lib/i486-linuxglibc2/2.7.2.2

and edit the file specs found in this directory. In this file, change
/lib/ld-linux.so.1 to /lib/ld-linux.so.2. You also need to remove all
expressions %{...:-lgmon} in the file, since glibc does not use the
gmon library for profiling. A sample specs file can be found in the
``Sample specs file'' section.

4.4. Updating header file links.

You need create links in your new include directory to other include
directories:

cd /usr/i486-linuxglibc2/include
ln -s /usr/src/linux/include/linux
ln -s /usr/src/linux/include/asm
ln -s /usr/X11R6/include/X11

You might also have other libraries such as ncurses which need their
header files put in this directory. You should copy or link the files
from /usr/include. (Some libraries may need to be recompiled with
glibc2 in order to work with it. In these cases, just compile and
install the package to /usr/i486-linuxglibc2.)

4.5. Testing your installation.

To test the installation, create the following program in a file
glibc.c:

#include <stdio.h>

main()
{
printf("hello world!\n");
}

and compile with the options of "-b <base install directory> -nostdinc
-I<install directory>/include -I/usr/lib/gcc-lib/<new system dir>/<gcc
version>/include":

% gcc -b i486-linuxglibc2 -nostdinc -I/usr/i486-linuxglibc2/include -I/usr/lib/gcc-lib/i486-linuxglibc2/2.7.2.2/include glibc.c -o glibc

Use ldd to verify the program was linked with glibc2, and not your old
libc:

% ldd glibc
libc.so.6 => /usr/i486-linuxglibc2/lib/libc-2.0.6.so (0x4000d000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

If it compiles, the links check out, and it generates "hello world!"
when run, the installation succeeded.

5. Installing as the primary C library.

This section covers installing glibc 2 as your primary C library. Any
new programs you compile will be linked with this library, unless you
use special compile options to link with another version.

If you are are using Redhat or Debian and have downloaded the
appropriate rpm or deb files, see the Redhat or Debian installion
instructions. You can then skip this section.

5.1. Building the library from source.

This section explains how to compile glibc 2 and add-ons from the
sources. You must compile the library if you want to change
optimization or configuration options or use a package you do not have
the binaries for.

5.1.1. Prerequisites.

o About 150 MB free disk space

o GNU make 3.75

o gcc >= 2.7.2 (better 2.7.2.1)

o binutils 2.8.1 (for alpha you need a snapshot)

o bash 2.0

o autoconf 2.12 (if you change configure.in)

o texinfo 3.11

On an i586@133 with 64 MB of RAM, it takes about 3 hours to compile
with full libraries with add-ons. On a loaded i686@200, it takes
about half an hour.

5.1.2. Extracting the source.

You need to extract the source from the archives so you can compile
it. The best way to do this is:

tar xzf glibc-2.0.6.tar.gz
cd glibc-2.0.6
tar xzf ../glibc-linuxthreads-2.0.6.tar.gz
tar xzf ../glibc-crypt-2.0.6.tar.gz
tar xzf ../glibc-localedata-2.0.6.tar.gz

This will put linuxthreads, crypt, and localedata directories in the
glibc-2.0.6 directory where configure can find these add-ons.

5.1.3. Configuring.

In the glibc-2.0.6 directory, create a directory named compile, and cd
into it. All work will be done in this directory, which will simplify
cleaning up. (The developers have not been very concerned with
getting 'make clean' perfect yet.)

mkdir compile
cd compile

Run ../configure. To use the add-on packages, you need to specify
them with --enable-add-ons, such as --enable-add-ons=linux-
threads,crypt,localedata. You probably will also want to specify
paths where it will be installed. To match the standard linux distri-
butions, specify --prefix=/usr. (When a prefix of /usr is specified
on a linux system, configure knows to adjust other paths to place
libc.so and other important libraries in /lib.) The whole configure
line would be:

../configure --enable-add-ons=linuxthreads,crypt,localedata --prefix=/usr

5.1.4. Compiling.

To compile and verify, run:

make
make check

5.2. Preparing for installation.

Now you need to move some files around to prepare for the new library,
whether you are installing from source or binaries. Any new program
compiled will be linked to glibc, but old programs which are not
statically linked will still depend on libc 5, so you can not just
overwrite the old version.

1. Create a new directory to hold the old files to:

mkdir -p /usr/i486-linuxlibc5/lib

2. The old header files must be evacuated from /usr/include:

mv /usr/include /usr/i486-linuxlibc5/include

3. Create a new include directory and set up the links to other
include directories:

mkdir /usr/include

ln -s /usr/src/linux/include/linux /usr/include/linux
ln -s /usr/src/linux/include/asm /usr/include/asm
ln -s /usr/X11R6/include/X11 /usr/include/X11
ln -s /usr/lib/g++-include /usr/include/g++

The links may need adjusting according to your distribution. At least
Slackware puts g++ headers in /usr/local/g++-include, while Debian
puts the headers in /usr/include/g++, and links /usr/lib/g++-include
to /usr/include/g++. In the later case, you probably will want to
move the original g++ include directory back to /usr/include.

4. Restore any extra header files and links. Some non-standard
libraries such as ncurses put files in /usr/include or put a link
to their include directories in the /usr/include. These files and
links need to be restored in order to use the extra libraries
properly.

5. Add your new library directory (such as /usr/i486-linuxlibc5/lib)
at the top of your /etc/ld.so.conf file. You should have ld.so
1.8.8 or better installed to avoid getting strange messages once
glibc is installed.

6. Move/copy all the old C libraries into the new directory.

mv /usr/lib/libbsd.a /usr/i486-linuxlibc5/lib
mv /usr/lib/libc.a /usr/i486-linuxlibc5/lib
mv /usr/lib/libgmon.a /usr/i486-linuxlibc5/lib
mv /usr/lib/libm.a /usr/i486-linuxlibc5/lib
mv /usr/lib/libmcheck.a /usr/i486-linuxlibc5/lib
mv /usr/lib/libc.so /usr/i486-linuxlibc5/lib
mv /usr/lib/libm.so /usr/i486-linuxlibc5/lib
cp /lib/libm.so.5.* /usr/i486-linuxlibc5/lib
cp /lib/libc.so.5.* /usr/i486-linuxlibc5/lib

libm.so.5 and libc.so.5 should be copied and not moved if /usr is a
seperate partition from /, because they are required by programs used
to start linux and must be located on the root drive partition.

7. Move the /usr/lib/*.o files into the new directory.

mv /usr/lib/crt1.o /usr/i486-linuxlibc5/lib
mv /usr/lib/crti.o /usr/i486-linuxlibc5/lib
mv /usr/lib/crtn.o /usr/i486-linuxlibc5/lib
mv /usr/lib/gcrt1.o /usr/i486-linuxlibc5/lib

8. Update your library cache after your libraries are moved.

ldconfig -v

5.3. Installing from the binary package.

If you are installing glibc from precompiled binaries, you first want
to check what is in the package before you install the binaries:

tar -tzvvf glibc-2.0.bin.i386.tar.gz
tar -tzvvf glibc-crypt-2.0.bin.i386.tar.gz

If you are happy with that, you can install glibc with:

cd /
tar -xzf glibc-2.0.bin.i386.tar.gz
tar -xzf glibc-crypt-2.0.bin.i386.tar.gz
ldconfig -v

If you have a different architecture or version, substitute the proper
file names.

The most recent glibc version is generally not available as a binary
package, and it is strongly recommended that you run the most recent
version to avoid bugs. If you can not build the library yourself,
grab a binary package of glibc from one of the distributions that is
based on glibc (e.g. RedHat) and install this.

5.4. Installing from the source.

To install the library from source, run as root from the compile/
directory:

make install
ldconfig -v

5.5. Updating the gcc specs.

The final step of the installation (for both binary and source
installs) is to update the gcc specs file so you can link your
programs properly. To determine which specs file is the one used by
gcc, use:

% gcc -v
reading specs from /usr/lib/gcc-lib/i486-unknown-linux/2.7.2.2/specs
gcc version 2.7.2.2

In this case, i486-unknown-linux is the system, and 2.7.2.2 is the
version. You need to copy the /usr/lib/gcc-lib/<system> to the old
system directory:

cd /usr/lib/gcc-lib/
cp -r i486-unknown-linux i486-linuxlibc5

Change into the original directory and version directory

cd /usr/lib/gcc-lib/i486-unknown-linux/2.7.2.2

and edit the file specs found in this directory. In this file, change
/lib/ld-linux.so.1 to /lib/ld-linux.so.2. You also need to remove all
expressions %{...:-lgmon} in the file, since glibc does not use the
gmon library for profiling. A sample specs file can be found in the
``Sample specs file'' section.

5.6. Testing your installation.

To test the installation, create the following program in a file
glibc.c:

#include <stdio.h>

main()
{
printf("hello world!\n");
}

and compile the program.

% gcc glibc.c -o glibc

Use ldd to verify the program was linked with glibc2, and not your old
libc:

% ldd glibc
libc.so.6 => /lib/libc.so.6 (0x4000e000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

If this compiles and generates "hello world!" when run, the installa-
tion was successful.

6. Compiling with the non-primary libc.

There are times you will want to use an alternate library to compile
your programs with. This section explains how to accomplish this,
using the directories and installation names used in the examples in
the previous two sections. Remember to change the names to fit your
setup.

6.1. A warning when using non-primary libcs.

Before compiling any programs which is used in the system boot
process, remember that if the program is dynamically linked and is
used before the non-root partitions are mounted, all linked libraries
must be on the root partition. Following the installation process in
the previous section for installing glibc as your primary C library,
the old libc is left in /lib, which will be on your root partition.
This means all of your programs will still work during booting.
However, if /usr is on a different partition and you install glibc as
a test library in /usr/i486-linuxglibc2, any new programs you compile
with glibc will not work until your /usr partition is mounted.

6.2. Compiling programs with a test glibc.

To compile a program with a test-install glibc, you need to reset the
include paths to point to the glibc includes. Specifying "-nostdinc"
will negate the normal paths, and "-I/usr/i486-linuxglibc2/include"
will point to the glibc includes. You will also need to specify the
gcc includes, which are found in /usr/lib/gcc-
lib/i486-linuxglibc2/2.7.2.2/include (assuming you installed the test
lib in i486-linuxglibc2 with gcc version 2.7.2.2).

To link a program with a test-install glibc, you need to specify the
gcc setup. This is done by using the option "-b i486-linuxglibc2".

For most programs, you can specify these new options by adding them to
the $CFLAGS and $LDFLAGS makefile options:

CFLAGS = -nostdinc -I/usr/i486-linuxglibc2/include -I/usr/lib/gcc-lib/i486-linuxglibc2/2.7.2.2/include -b i486-linuxglibc2
LDFLAGS = -b i486-linuxglibc2

If you are using a configure script, define the $CFLAGS and $LDFLAGS
shell variables (by using env/setenv for csh/tcsh, or set/export for
sh/bash/etc) before running configure. The makefiles generated by
this should contain the proper $CFLAGS and $LDFLAGS. Not all config-
ure scripts will pick up the variables, so you should check after run-
ning configure and edit the makefiles by hand if necessary.

If the programs you are compiling only call gcc (and not cpp or
binutils directly), you can use the following script to save having to
specify all of the options each time:

#!/bin/bash
/usr/bin/gcc -b i486-linuxglibc2 -nostdinc \
-I/usr/i486-linuxglibc2/include \
-I/usr/lib/gcc-lib/i486-linuxglibc2/2.7.2.2/include "$@"

You can then use this script instead of "gcc" when compiling.

6.3. Compiling programs with libc 5 when glibc is primary library.

To compile a program with your old libraries when you have installed
glibc as your main library, you need to reset the include paths to the
old includes. Specifying "-nostdinc" will negate the normal paths,
and "-I/usr/i486-linuxlibc5/include" will point to the glibc includes.
You must also specify "-I/usr/lib/gcc-
lib/i486-linuxlibc5/2.7.2.2/include" to include the gcc specific
includes. Remember to adjust these paths based on the what you named
the new directories and your gcc version.

To link a program with your old libc, you need to specify the gcc
setup. This is done by using the option "-b i486-linuxlibc5".

For most programs, you can specify these new options by appending them
to the $CFLAGS and $LDFLAGS makefile options:

CFLAGS = -nostdinc -I/usr/i486-linuxlibc5/include -I/usr/lib/gcc-lib/i486-linuxlibc5/2.7.2.2/include -b i486-linuxlibc5
LDFLAGS = -b i486-linuxlibc5

If you are using a configure script, define the $CFLAGS and $LDFLAGS
shell variables (by using env/setenv for csh/tcsh, or set/export for
sh/bash/etc) before running configure. The makefiles generated by
this should contain the proper $CFLAGS and $LDFLAGS. Not all config-
ure scripts will pick up the variables, so you should check after run-
ning configure and edit the makefiles by hand if necessary.

If the programs you are compiling only call gcc (and not cpp or
binutils directly), you can use the following script to save having to
specify all of the options each time:

#!/bin/bash
/usr/bin/gcc -b i486-linuxlibc5 -nostdinc \
-I/usr/i486-linuxlibc5/include \
-I/usr/lib/gcc-lib/i486-linuxlibc5/2.7.2.2/include "$@"

You can then use this script instead of "gcc" when compiling.

7. Compiling C++ programs.

Libg++ uses parts of the math library, so is link to libm. Since your
existing libg++ will be compiled with your old library, you will have
to recompile libg++ with glibc or get a binary copy. The latest
source for libg++ along with a binary linked with glibc (for x86) can
be found at <ftp://ftp.yggdrasil.com/private/hjl/>.

7.1. Installing libg++ for a test glibc install.

If you have installed glibc as a test library, you need to install the
files into the directory you installed glibc into (such as
/usr/i486-linuxglibc2 for the example in the previous sections). If
you are installing from the binary package (which i would recommend,
since i never had any luck compiling libg++ this way), you need to
extract the files into a temporary directory and move all the usr/lib/
files into the <install directory>/lib/ directory, the usr/include/
files into the <install directory>/include/ directory (remember to
delete your include/g++ link first!), and the usr/bin/ files into the
<install directory>/bin/ directory.

7.2. Installing libg++ for a primary glibc install.

If you have installed glibc as the primary library, you first need to
move your old libg++ files into your old libc directory if you still
want to be able to compile g++ programs with your old libc. Probably
the easiest way to do this is by installing a new copy of the libg++
compiled with libc 5 as in the previous section, and then installing
the glibc version normally.

7.3. Compiling C++ programs with the non-primary libc.

If you are trying to compile a C++ program with a non-primary libc,
you will need to include the g++ include dir, which in the examples
above would be /usr/i486-linuxglibc2/include/g++ for a test glibc
install or /usr/i486-linuxlibc5/include/g++ for a primary glibc
install. This can usually be done by appending the $CXXFLAGS
variable:

CXXFLAGS = -nostdinc -I/usr/i486-linuxglibc2/include -I/usr/lib/gcc-lib/i486-linuxglibc2/2.7.2.2/include -I/usr/i486-linuxlibc5/include/g++ -b i486-linuxglibc2

8. Problems.

The glibc package contains a FAQ with additional information that you
should check if you are having problems. An online version is also
available at <http://www.imaxx.net/~thrytis/glibc/glibc-FAQ.html>.
Below are some tips for solving problems which are not covered in the
FAQ or are covered here in more detail.

8.1. Host names do not resolve.

Glibc 2 uses a different method than libc 5 in looking up host names.
The glibc name server switch (NSS) code looks for a file
/etc/nsswitch.conf. If host names are not resolving for you when
using a glibc 2 application and your /etc/resolv.conf is configured
correctly, check if you have the /etc/nsswitch.conf file. If you do
not have this file, you can create one containing the line:

hosts: files dns

It will now look for /etc/resolv.conf to find the nameservers.

You should look at the section of the libc info pages describing the
nsswitch.conf file for more details.

9. Reporting bugs.

If you think the lib is buggy, please read first the FAQ. It might be
that others had the same problem and there's an easy solution. You
should also check the section "Recommended Tools to Install the GNU C
Library" in the INSTALL file since some bugs are bugs of the tools and
not of glibc.

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.

Next, go to <http://www-gnats.gnu.org:8080/cgi-bin/wwwgnats.pl>, and
look through the bug database. Check here to verify the problem has
not already be reported. You should also look at the file BUGS
(distributed with libc) to check for known bugs.

Once you're sure you've found a new 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, the versions of the GNU C
library, the GNU CC compiler, and the GNU Binutils 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.

All bug reports for the GNU C library should be sent using the
glibcbug shell script which comes with the GNU libc to <[email protected]>
(the older address <[email protected]> is still working), or
submitted through the GNATS web interface at <http://www-
gnats.gnu.org:8080/cgi-bin/wwwgnats.pl>.

Suggestions and questions should be sent to the mailing list at <bugs-
[email protected]>. If you don't read the gnewsgroup
gnu.bug.glibc, you can subscribe to the list by asking <bug-glibc-
[email protected]>.

Please DO NOT send bug report for the GNU C library to <bug-
[email protected]>. That list is for bug reports for GNU CC. GNU
CC and the GNU C library are separate entities maintained by separate
people.

10. Sample specs file.

Included here is a sample specs file for glibc 2 which is used by gcc
for compiling and linking. It should be found in the directory
/usr/lib/gcc-lib/<new system dir>/<gcc version>. If you are running
an x86 system, you probably can copy this section to the file exactly.

*asm:
%{V} %{v:%{!V:-V}} %{Qy:} %{!Qn:-Qy} %{n} %{T} %{Ym,*} %{Yd,*} %{Wa,*:%*}

*asm_final:
%{pipe:-}

*cpp:
%{fPIC:-D__PIC__ -D__pic__} %{fpic:-D__PIC__ -D__pic__} %{!m386:-D__i486__} %{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}

*cc1:
%{profile:-p}

*cc1plus:

*endfile:
%{!shared:crtend.o%s} %{shared:crtendS.o%s} crtn.o%s

*link:
-m elf_i386 %{shared:-shared} %{!shared: %{!ibcs: %{!static: %{rdynamic:-export-dynamic} %{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.2}}
%{static:-static}}}

*lib:
%{!shared: %{pthread:-lpthread} %{profile:-lc_p} %{!profile: -lc}}

*libgcc:
-lgcc

*startfile:
%{!shared: %{pg:gcrt1.o%s} %{!pg:%{p:gcrt1.o%s} %{!p:%{profile:gcrt1.o%s}
%{!profile:crt1.o%s}}}} crti.o%s %{!shared:crtbegin.o%s} %{shared:crtbeginS.o%s}

*switches_need_spaces:

*signed_char:
%{funsigned-char:-D__CHAR_UNSIGNED__}

*predefines:
-D__ELF__ -Dunix -Di386 -Dlinux -Asystem(unix) -Asystem(posix) -Acpu(i386) -Amachine(i386)

*cross_compile:
0

*multilib:
. ;

11. Miscellanea.

11.1. Further information.

11.1.1. Web pages.

o FSF's GNU C Library Home Page
<http://www.gnu.org/software/libc/libc.html>
o Using GNU Libc 2 with Linux <http://www.imaxx.net/~thrytis/glibc/>

o Installing glibc-2 on Linux <http://huizen.dds.nl/~frodol/glibc/>.

o Debian libc5 to libc6 Mini-HOWTO
<http://www.gate.net/~storm/FAQ/libc5-libc6-Mini-HOWTO.html>.

11.1.2. Newgroups.

o comp.os.linux.development.system

o comp.os.linux.development.apps

o linux.dev.kernel

o gnu.bugs.glibc

11.1.3. Mailing lists.

Glibc 2 Linux discussion list.
This list is intended for discussion among Linux users who have
installed glibc2, the new GNU C libraries. Topics might include
compatibility issues and questions about the compilation of code
in a Linux/glibc setting. To subscribe, send mail to
[email protected]
<mailto:[email protected]> with a body of "subscribe
glibc-linux <your email address>.

Archives for this mailing list can be found at
<http://www.progressive-comp.com/Lists/?l=linux-
glibc&r=1&w=2#linux-glibc>

11.2. Credits.

Most of this information was stolen from the GNU Libc web page
<http://www.gnu.org/software/libc/libc.html> and from Ulrich Drepper's
<[email protected]> glibc 2 announcement and his comments.
Andreas Jaeger <[email protected]> provided some of the
Reporting bugs section.

The following people have provided information and feedback for this
document:

o Allex <[email protected]>

o Mark Brown <[email protected]>

o Ulrich Drepper <[email protected]>

o Scott K. Ellis <[email protected]>

o Aron Griffis <[email protected]>

o Andreas Jaeger <[email protected]>

o Hank Leininger <[email protected]>

o Frodo Looijaard <[email protected]>

o Ryan McGuire <[email protected]>

o Shaya Potter <[email protected]>

o Les Schaffer <[email protected]>

o Andy Sewell <[email protected]>

o Gary Shea <[email protected]>

o Stephane <[email protected]>

o Jan Vandenbos <[email protected]>

o Michael Wolf <[email protected]>

Translations of this document are being done by:

o Chinese: Allex <[email protected]>

o French: Olivier Tharan <[email protected]>

o Japanese: Kazuyuki Okamoto <[email protected]>

11.3. Feedback.

Besides writing this HOWTO, maintaining the glibc 2 for Linux
<http://www.imaxx.net/~thrytis/glibc> page, and using it on my
machine, I have nothing to do with the glibc project. I am far from
knowledgeable on this topic, though I try to help with problems mailed
to me. I welcome any feedback, corrections, or suggestions you have
to offer. Please send them to [email protected]
<mailto:[email protected]>.

11.4. Copyright.

Copyright (c) 1997 by Eric Green. This document may be distributed
under the terms set forth in the LDP license.