Cross-Compiled Linux From Scratch - Version SYSVINIT-20170702-PowerPC64-Multilib

Chapter 10. Installing Basic System Software

10.8. Glibc-2.25 64-Bit

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.

10.8.1. Installation of Glibc

At the end of the installation, the build system will run a sanity test to make sure everything installed properly. This script performs its tests by attempting to compile test programs against certain libraries. However it does not specify the path to ld.so, and our toolchain is still configured to use the one in /tools. The following set of commands will force the script to use the complete path of the new ld.so that was just installed: 

LINKER=$(readelf -l /tools/bin/bash | sed -n 's@.*interpret.*/tools\(.*\)]$@\1@p')
sed -i "s|libs -o|libs -L/usr/lib64 -Wl,-dynamic-linker=${LINKER} -o|" \
  scripts/test-installation.pl
unset LINKER

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

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

Configure Glibc to install its 64-bit libraries into /lib64: 

echo "libc_cv_slibdir=/lib64" >> config.cache

Prepare Glibc for compilation: 

CC="gcc ${BUILD64}" CXX="g++ ${BUILD64}" \
../glibc-2.25/configure \
    --prefix=/usr \
    --enable-kernel=3.12.0 \
    --libexecdir=/usr/lib64/glibc \
    --libdir=/usr/lib64 \
    --enable-obsolete-rpc \
    --enable-stack-protector=strong \
    --cache-file=config.cache

The meaning of the new configure option:

--libexecdir=/usr/lib64/glibc

This changes the location for hard links to the getconf utility from their default of /usr/libexec to /usr/lib64/glibc.

Compile the package: 

make
[Important]

Important

Due to Glibc's critical role in a properly functioning system, the CLFS developers strongly recommend running the testsuite.

Use the following commands to run the test suite and output any test failures: 

make check

The Glibc test suite is highly dependent on certain functions of the host system, in particular the kernel. The posix/annexc and conform/run-conformtest tests normally fail and you should see Error 1 (ignored) in the output. Apart from this, the Glibc test suite is always expected to pass. However, in certain circumstances, some failures are unavoidable. If a test fails because of a missing program (or missing symbolic link), or a segfault, you will see an error code greater than 127 and the details will be in the log. More commonly, tests will fail with Error 2 - for these, the contents of the corresponding .out file, e.g. posix/annexc.out may be informative. Here is a list of the most common issues:

  • The nptl/tst-clock2, nptl/tst-attr3, tst/tst-cputimer1, and rt/tst-cpuclock2 tests have been known to fail. The reason is not completely understood, but indications are that minor timing issues can trigger these failures.

  • The math tests sometimes fail. Certain optimization settings are known to be a factor here.

  • If you have mounted the CLFS partition with the noatime option, the atime test will fail. As mentioned in Section 2.5, “Mounting the New Partition”, do not use the noatime option while building CLFS.

  • When running on older and slower hardware, some tests can fail because of test timeouts being exceeded. Modifying the make check command to set a TIMEOUTFACTOR is reported to help eliminate these errors (e.g. TIMEOUTFACTOR=16 make -k check).

  • posix/tst-getaddrinfo4 will always fail due to not having a network connection when the test is run.

Install the package, and remove unneeded files from /usr/include/rpcsvc: 

make install &&
rm -v /usr/include/rpcsvc/*.x

Install the configuration file and runtime directory for nscd: 

cp -v ../glibc-2.25/nscd/nscd.conf /etc/nscd.conf
mkdir -pv /var/cache/nscd

10.8.2. Internationalization

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

make localedata/install-locales

To save time, an alternative to running the previous command (which generates and installs every locale listed in the glibc-2.25/localedata/SUPPORTED file) 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 -pv /usr/lib/locale
localedef -i cs_CZ -f UTF-8 cs_CZ.UTF-8
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 CLFS and CBLFS. Because of the various problems that arise due to application programmers making assumptions that break in such locales, CLFS 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 CLFS developers not to support such complex locales at this time. 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-ng package) does not work properly in them. Various attempts to circumvent these restrictions are documented in internationalization-related hints.

10.8.3. 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

Install timezone data: 

tar -xf ../tzdata2017b.tar.gz

ZONEINFO=/usr/share/zoneinfo
mkdir -pv $ZONEINFO/{posix,right}

for tz in etcetera southamerica northamerica europe africa antarctica \
          asia australasia backward pacificnew systemv; do
    zic -L /dev/null   -d $ZONEINFO       -y "sh yearistype.sh" ${tz}
    zic -L /dev/null   -d $ZONEINFO/posix -y "sh yearistype.sh" ${tz}
    zic -L leapseconds -d $ZONEINFO/right -y "sh yearistype.sh" ${tz}
done

cp -v zone.tab zone1970.tab iso3166.tab $ZONEINFO
zic -d $ZONEINFO -p America/New_York
unset ZONEINFO

The meaning of the zic commands:

zic -L /dev/null ...

This creates posix timezones, without any leap seconds. It is conventional to put these in both zoneinfo and zoneinfo/posix. It is necessary to put the POSIX timezones in zoneinfo, otherwise various test-suites will report errors. On an embedded system, where space is tight and you do not intend to ever update the timezones, you could save 1.9MB by not using the posix directory, but some applications or test-suites might give less good results

zic -L leapseconds ...

This creates right timezones, including leap seconds. On an embedded system, where space is tight and you do not intend to ever update the timezones, or care about the correct time, you could save 1.9MB by omitting the right directory.

zic ... -p ...

This creates the posixrules file. We use New York because POSIX requires the daylight savings time rules to be in accordance with US rules.

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 -v /usr/share/zoneinfo/[xxx] \
    /etc/localtime

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

10.8.4. Configuring The Dynamic Loader

By default, the dynamic loader (/lib/ld.so.1 for 32bit executables and /lib/ld64.so for 64bit executables) searches through /lib, /lib64, /usr/lib, and /usr/lib64 for dynamic libraries that are needed by programs as they are run. However, if there are libraries in directories other than these, they need to be added to the /etc/ld.so.conf file in order for the dynamic loader to find them. Some directories that are commonly known to contain additional libraries are /usr/local/lib, /usr/local/lib64, /opt/lib, and /opt/lib64, 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
/usr/local/lib64
/opt/lib
/opt/lib64

# End /etc/ld.so.conf
EOF

10.8.5. Contents of Glibc

Installed programs: catchsegv, gencat, getconf, getent, iconv, iconvconfig, ldconfig, ldd, lddlibc4, locale, localedef, makedb, mtrace, nscd, pcprofiledump, pldd, rpcgen, sln, sotruss, sprof, tzselect, xtrace, zdump, zic
Installed libraries: ld.so, libBrokenLocale.[a,so], libSegFault.so, libanl.[a,so], libc.[a,so], libc_nonshared.a, libcidn.[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], libpthread_nonshared.a, libresolv.[a,so], librpcsvc.a, librt.[a,so], libthread_db.so, libutil.[a,so]
Installed directories: /usr/include/arpa, /usr/include/bits, /usr/include/gnu, /usr/include/net, /usr/include/netash, /usr/include/netatalk, /usr/include/netax25, /usr/include/neteconet, /usr/include/netinet, /usr/include/netipx, /usr/include/netiucv, /usr/include/netpacket, /usr/include/netrom, /usr/include/netrose, /usr/include/nfs, /usr/include/protocols, /usr/include/rpc, /usr/include/rpcsvc, /usr/include/scsi, /usr/include/sys, /usr/lib/audit, /usr/lib/gconv, /usr/lib/glibc, /usr/lib/locale, /usr/share/i18n, /usr/share/zoneinfo, /var/cache/ldconfig, /var/cache/nscd

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

makedb

Creates a simple database from textual input

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

pcprofiledump

Dumps information generated by PC profiling

pldd

Lists dynamic shared objects used by running processes

rpcgen

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

sln

A statically linked program that creates symbolic links

sotruss

Traces shared library procedure calls of a specified command

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

libc

The main C library

libcidn

Used internally by Glibc for handling internationalized domain names in the getaddrinfo() function

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 (included in Glibc, but not built in a base CLFS system as it has additional dependencies) 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