Linux From Scratch - Version 6.1

Chapter 6. Installing Basic System Software

6.11. Glibc-2.3.4

The Glibc package contains the main C library. This library provides the basic routines for allocating memory, searching directories, opening and closing files, reading and writing files, string handling, pattern matching, arithmetic, and so on.

Approximate build time: 12.3 SBU
Required disk space: 476
Installation depends on: Bash, Binutils, Coreutils, Diffutils, Gawk, GCC, Gettext, Grep, Make, Perl, Sed, and Texinfo

6.11.1. Installation of Glibc

This package is known to have issues when its default optimization flags (including the -march and -mcpu options) are changed. If any environment variables that override default optimizations have been defined, such as CFLAGS and CXXFLAGS, unset them when building Glibc.

The Glibc build system is self-contained and will install perfectly, even though the compiler specs file and linker are still pointing at /tools. The specs and linker cannot be adjusted before the Glibc install because the Glibc autoconf tests would give false results and defeat the goal of achieving a clean build.

The linuxthreads tarball contains the man pages for the threading libraries installed by Glibc. Unpack the tarball from within the Glibc source directory: 

tar -xjvf /sources/glibc-linuxthreads-2.3.4.tar.bz2

Glibc has two tests which fail when the running kernel is 2.6.11.x The problem has been determined to be with the tests themselves, not with the libc nor the kernel. This patch fixes the problem: 

patch -Np1 -i ../glibc-2.3.4-fix_test-1.patch

The Glibc documentation recommends building Glibc outside of the source directory in a dedicated build directory: 

mkdir ../glibc-build
cd ../glibc-build

Prepare Glibc for compilation: 

../glibc-2.3.4/configure --prefix=/usr \
    --disable-profile --enable-add-ons \
    --enable-kernel=2.6.0 --libexecdir=/usr/lib/glibc

The meaning of the new configure options:

--libexecdir=/usr/lib/glibc

This changes the location of the pt_chown program from its default of /usr/libexec to /usr/lib/glibc.

Compile the package: 

make
[Important]

Important

In this section, the test suite for Glibc is considered critical. Do not skip it under any circumstance.

Test the results: 

make check

The Glibc test suite is highly dependent on certain functions of the host system, in particular the kernel. In general, the Glibc test suite is always expected to pass. However, in certain circumstances, some failures are unavoidable. This is a list of the most common issues:

  • The math tests sometimes fail when running on systems where the CPU is not a relatively new genuine Intel or authentic AMD. Certain optimization settings are also known to be a factor here.

  • The gettext test sometimes fails due to host system issues. The exact reasons are not yet clear.

  • If you have mounted the LFS partition with the noatime option, the atime test will fail. As mentioned in Section 2.4, “Mounting the New Partition”, do not use the noatime option while building LFS.

  • When running on older and slower hardware, some tests can fail because of test timeouts being exceeded.

Though it is a harmless message, the install stage of Glibc will complain about the absence of /etc/ld.so.conf. Prevent this warning with: 

touch /etc/ld.so.conf

Install the package: 

make install

The locales that can make the system respond in a different language were not installed by the above command. Install this with: 

make localedata/install-locales

To save time, an alternative to running the previous command (which generates and installs every locale Glibc is aware of) is to install only those locales that are wanted and needed. This can be achieved by using the localedef command. Information on this command is located in the INSTALL file in the Glibc source. However, there are a number of locales that are essential in order for the tests of future packages to pass, in particular, the libstdc++ tests from GCC. The following instructions, instead of the install-locales target used above, will install the minimum set of locales necessary for the tests to run successfully: 

mkdir -p /usr/lib/locale
localedef -i de_DE -f ISO-8859-1 de_DE
localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro
localedef -i en_HK -f ISO-8859-1 en_HK
localedef -i en_PH -f ISO-8859-1 en_PH
localedef -i en_US -f ISO-8859-1 en_US
localedef -i es_MX -f ISO-8859-1 es_MX
localedef -i fa_IR -f UTF-8 fa_IR
localedef -i fr_FR -f ISO-8859-1 fr_FR
localedef -i fr_FR@euro -f ISO-8859-15 fr_FR@euro
localedef -i it_IT -f ISO-8859-1 it_IT
localedef -i ja_JP -f EUC-JP ja_JP

Some locales installed by the make localedata/install-locales command above are not properly supported by some applications that are in the LFS and BLFS books. Because of the various problems that arise due to application programmers making assumptions that break in such locales, LFS should not be used in locales that utilize multibyte character sets (including UTF-8) or right-to-left writing order. Numerous unofficial and unstable patches are required to fix these problems, and it has been decided by the LFS developers not to support such complex locales. This applies to the ja_JP and fa_IR locales as well—they have been installed only for GCC and Gettext tests to pass, and the watch program (part of the Procps package) does not work properly in them. Various attempts to circumvent these restrictions are documented in internationalization-related hints.

Build the linuxthreads man pages, which are a great reference on the threading API (applicable to NPTL as well): 

make -C ../glibc-2.3.4/linuxthreads/man

Install these pages: 

make -C ../glibc-2.3.4/linuxthreads/man install

6.11.2. Configuring Glibc

The /etc/nsswitch.conf file needs to be created because, although Glibc provides defaults when this file is missing or corrupt, the Glibc defaults do not work well in a networked environment. The time zone also needs to be configured.

Create a new file /etc/nsswitch.conf by running the following: 

cat > /etc/nsswitch.conf << "EOF"
# Begin /etc/nsswitch.conf

passwd: files
group: files
shadow: files

hosts: files dns
networks: files

protocols: files
services: files
ethers: files
rpc: files

# End /etc/nsswitch.conf
EOF

To determine the local time zone, run the following script: 

tzselect

After answering a few questions about the location, the script will output the name of the time zone (e.g., EST5EDT or Canada/Eastern). Then create the /etc/localtime file by running: 

cp --remove-destination /usr/share/zoneinfo/[xxx] \
    /etc/localtime

Replace [xxx] with the name of the time zone that tzselect provided (e.g., Canada/Eastern).

The meaning of the cp option:

--remove-destination

This is needed to force removal of the already existing symbolic link. The reason for copying the file instead of using a symlink is to cover the situation where /usr is on a separate partition. This could be important when booted into single user mode.

6.11.3. Configuring Dynamic Loader

By default, the dynamic loader (/lib/ld-linux.so.2) searches through /lib and /usr/lib for dynamic libraries that are needed by programs as they are run. However, if there are libraries in directories other than /lib and /usr/lib, these need to be added to the /etc/ld.so.conf file in order for the dynamic loader to find them. Two directories that are commonly known to contain additional libraries are /usr/local/lib and /opt/lib, so add those directories to the dynamic loader's search path.

Create a new file /etc/ld.so.conf by running the following: 

cat > /etc/ld.so.conf << "EOF"
# Begin /etc/ld.so.conf

/usr/local/lib
/opt/lib

# End /etc/ld.so.conf
EOF

6.11.4. Contents of Glibc

Installed programs: catchsegv, gencat, getconf, getent, iconv, iconvconfig, ldconfig, ldd, lddlibc4, locale, localedef, mtrace, nscd, nscd_nischeck, pcprofiledump, pt_chown, rpcgen, rpcinfo, sln, sprof, tzselect, xtrace, zdump, and zic
Installed libraries: ld.so, libBrokenLocale.[a,so], libSegFault.so, libanl.[a,so], libbsd-compat.a, libc.[a,so], libcrypt.[a,so], libdl.[a,so], libg.a, libieee.a, libm.[a,so], libmcheck.a, libmemusage.so, libnsl.a, libnss_compat.so, libnss_dns.so, libnss_files.so, libnss_hesiod.so, libnss_nis.so, libnss_nisplus.so, libpcprofile.so, libpthread.[a,so], libresolv.[a,so], librpcsvc.a, librt.[a,so], libthread_db.so, and libutil.[a,so]

Short Descriptions

catchsegv

Can be used to create a stack trace when a program terminates with a segmentation fault

gencat

Generates message catalogues

getconf

Displays the system configuration values for file system specific variables

getent

Gets entries from an administrative database

iconv

Performs character set conversion

iconvconfig

Creates fastloading iconv module configuration files

ldconfig

Configures the dynamic linker runtime bindings

ldd

Reports which shared libraries are required by each given program or shared library

lddlibc4

Assists ldd with object files

locale

Tells the compiler to enable or disable the use of POSIX locales for built-in operations

localedef

Compiles locale specifications

mtrace

Reads and interprets a memory trace file and displays a summary in human-readable format

nscd

A daemon that provides a cache for the most common name service requests

nscd_nischeck

Checks whether or not secure mode is necessary for NIS+ lookup

pcprofiledump

Dumps information generated by PC profiling

pt_chown

A helper program for grantpt to set the owner, group and access permissions of a slave pseudo terminal

rpcgen

Generates C code to implement the Remote Procecure Call (RPC) protocol

rpcinfo

Makes an RPC call to an RPC server

sln

A statically linked ln program

sprof

Reads and displays shared object profiling data

tzselect

Asks the user about the location of the system and reports the corresponding time zone description

xtrace

Traces the execution of a program by printing the currently executed function

zdump

The time zone dumper

zic

The time zone compiler

ld.so

The helper program for shared library executables

libBrokenLocale

Used by programs, such as Mozilla, to solve broken locales

libSegFault

The segmentation fault signal handler

libanl

An asynchronous name lookup library

libbsd-compat

Provides the portability needed in order to run certain Berkey Software Distribution (BSD) programs under Linux

libc

The main C library

libcrypt

The cryptography library

libdl

The dynamic linking interface library

libg

A runtime library for g++

libieee

The Institute of Electrical and Electronic Engineers (IEEE) floating point library

libm

The mathematical library

libmcheck

Contains code run at boot

libmemusage

Used by memusage to help collect information about the memory usage of a program

libnsl

The network services library

libnss

The Name Service Switch libraries, containing functions for resolving host names, user names, group names, aliases, services, protocols, etc.

libpcprofile

Contains profiling functions used to track the amount of CPU time spent in specific source code lines

libpthread

The POSIX threads library

libresolv

Contains functions for creating, sending, and interpreting packets to the Internet domain name servers

librpcsvc

Contains functions providing miscellaneous RPC services

librt

Contains functions providing most of the interfaces specified by the POSIX.1b Realtime Extension

libthread_db

Contains functions useful for building debuggers for multi-threaded programs

libutil

Contains code for “standard” functions used in many different Unix utilities