mirror of
https://git.linuxfromscratch.org/lfs.git
synced 2025-01-18 13:07:50 +00:00
39679232f7
Explain it once we use it. Also fix an error in the text (we don't make files executable, we only make directories searchable).
251 lines
10 KiB
XML
251 lines
10 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
|
|
<!ENTITY % general-entities SYSTEM "../general.ent">
|
|
%general-entities;
|
|
]>
|
|
|
|
<sect1 id="ch-preps-settingenviron">
|
|
<?dbhtml filename="settingenvironment.html"?>
|
|
|
|
<title>Setting Up the Environment</title>
|
|
|
|
<para>Set up a good working environment by creating two new startup files
|
|
for the <command>bash</command> shell. While logged in as user
|
|
<systemitem class="username">lfs</systemitem>, issue the following command
|
|
to create a new <filename>.bash_profile</filename>:</para>
|
|
|
|
<screen><userinput>cat > ~/.bash_profile << "EOF"
|
|
<literal>exec env -i HOME=$HOME TERM=$TERM PS1='\u:\w\$ ' /bin/bash</literal>
|
|
EOF</userinput></screen>
|
|
|
|
<para>When logged on as user <systemitem class="username">lfs</systemitem>,
|
|
or when switched to the &lfs-user; user using an <command>su</command> command
|
|
with the <quote><parameter>-</parameter></quote> option,
|
|
the initial shell is a <emphasis>login</emphasis> shell which reads
|
|
the <filename>/etc/profile</filename> of the host (probably containing some
|
|
settings and environment variables) and then <filename>.bash_profile</filename>.
|
|
The <command>exec env -i.../bin/bash</command> command in the
|
|
<filename>.bash_profile</filename> file replaces the running shell with a new
|
|
one with a completely empty environment, except for the <envar>HOME</envar>,
|
|
<envar>TERM</envar>, and <envar>PS1</envar> variables. This ensures that no
|
|
unwanted and potentially hazardous environment variables from the host system
|
|
leak into the build environment.</para>
|
|
|
|
<para>The new instance of the shell is a <emphasis>non-login</emphasis>
|
|
shell, which does not read, and execute, the contents of the <filename>/etc/profile</filename> or
|
|
<filename>.bash_profile</filename> files, but rather reads, and executes, the
|
|
<filename>.bashrc</filename> file instead. Create the
|
|
<filename>.bashrc</filename> file now:</para>
|
|
|
|
<screen><userinput>cat > ~/.bashrc << "EOF"
|
|
<literal>set +h
|
|
umask 022
|
|
LFS=/mnt/lfs
|
|
LC_ALL=POSIX
|
|
LFS_TGT=$(uname -m)-lfs-linux-gnu
|
|
PATH=/usr/bin
|
|
if [ ! -L /bin ]; then PATH=/bin:$PATH; fi
|
|
PATH=$LFS/tools/bin:$PATH
|
|
CONFIG_SITE=$LFS/usr/share/config.site
|
|
export LFS LC_ALL LFS_TGT PATH CONFIG_SITE</literal>
|
|
EOF</userinput></screen>
|
|
|
|
<variablelist>
|
|
<title>The meaning of the settings in <filename>.bashrc</filename></title>
|
|
|
|
<varlistentry>
|
|
<term><parameter>set +h</parameter></term>
|
|
<listitem>
|
|
<para>The <command>set +h</command> command turns off
|
|
<command>bash</command>'s hash function. Hashing is ordinarily a useful
|
|
feature—<command>bash</command> uses a hash table to remember the
|
|
full path to executable files to avoid searching the <envar>PATH</envar>
|
|
time and again to find the same executable. However, the new tools should
|
|
be used as soon as they are installed. Switching off the hash function forces
|
|
the shell to search the <envar>PATH</envar> whenever a program is to
|
|
be run. As such, the shell will find the newly compiled tools in
|
|
<filename class="directory">$LFS/tools/bin</filename> as soon as they are
|
|
available without remembering a previous version of the same program
|
|
provided by the host distro, in
|
|
<filename class='directory'>/usr/bin</filename> or
|
|
<filename class='directory'>/bin</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>umask 022</parameter></term>
|
|
<listitem>
|
|
<para>Setting the umask as we've already explained in
|
|
<xref linkend='ch-partitioning-aboutlfs' role='.'/></para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>LFS=/mnt/lfs</parameter></term>
|
|
<listitem>
|
|
<para>The <envar>LFS</envar> variable should be set to the chosen mount
|
|
point.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>LC_ALL=POSIX</parameter></term>
|
|
<listitem>
|
|
<para>The <envar>LC_ALL</envar> variable controls the localization of certain
|
|
programs, making their messages follow the conventions of a specified country.
|
|
Setting <envar>LC_ALL</envar> to <quote>POSIX</quote> or <quote>C</quote>
|
|
(the two are equivalent) ensures that everything will work as expected in
|
|
the cross-compilation environment.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>LFS_TGT=$(uname -m)-lfs-linux-gnu</parameter></term>
|
|
<listitem>
|
|
<para>The <envar>LFS_TGT</envar> variable sets a non-default, but compatible machine
|
|
description for use when building our cross-compiler and linker and when
|
|
cross-compiling our temporary toolchain. More information is provided by
|
|
<xref linkend="ch-tools-toolchaintechnotes" role=""/>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>PATH=/usr/bin</parameter></term>
|
|
<listitem>
|
|
<para>Many modern Linux distributions have merged <filename
|
|
class="directory">/bin</filename> and <filename
|
|
class="directory">/usr/bin</filename>. When this is the case, the standard
|
|
<envar>PATH</envar> variable should be set to <filename
|
|
class="directory">/usr/bin/</filename> for the <xref
|
|
linkend="chapter-temporary-tools"/> environment. When this is not the
|
|
case, the following line adds <filename class="directory">/bin</filename>
|
|
to the path.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>if [ ! -L /bin ]; then PATH=/bin:$PATH; fi</parameter></term>
|
|
<listitem>
|
|
<para>If <filename class="directory">/bin</filename> is not a symbolic
|
|
link, it must be added to the <envar>PATH</envar> variable.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>PATH=$LFS/tools/bin:$PATH</parameter></term>
|
|
<listitem>
|
|
<para>By putting <filename class="directory">$LFS/tools/bin</filename> ahead of the
|
|
standard <envar>PATH</envar>, the cross-compiler installed at the beginning
|
|
of <xref linkend="chapter-cross-tools"/> is picked up by the shell
|
|
immediately after its installation. This, combined with turning off hashing,
|
|
limits the risk that the compiler from the host is used instead of the
|
|
cross-compiler.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>CONFIG_SITE=$LFS/usr/share/config.site</parameter></term>
|
|
<listitem>
|
|
<para>In <xref linkend="chapter-cross-tools"/> and
|
|
<xref linkend="chapter-temporary-tools"/>, if this variable is not set,
|
|
<command>configure</command> scripts
|
|
may attempt to load configuration items specific to some distributions from
|
|
<filename>/usr/share/config.site</filename> on the host system. Override
|
|
it to prevent potential contamination from the host.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><parameter>export ...</parameter></term>
|
|
<listitem>
|
|
<para>While the preceding commands have set some variables, in order
|
|
to make them visible within any sub-shells, we export them.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
<important>
|
|
|
|
<para>Several commercial distributions add an undocumented instantiation
|
|
of <filename>/etc/bash.bashrc</filename> to the initialization of
|
|
<command>bash</command>. This file has the potential to modify the
|
|
<systemitem class="username">lfs</systemitem>
|
|
user's environment in ways that can affect the building of critical LFS
|
|
packages. To make sure the <systemitem class="username">lfs</systemitem>
|
|
user's environment is clean, check for the
|
|
presence of <filename>/etc/bash.bashrc</filename> and, if present, move it
|
|
out of the way. As the <systemitem class="username">root</systemitem>
|
|
user, run:</para>
|
|
|
|
<screen role="nodump"><userinput>[ ! -e /etc/bash.bashrc ] || mv -v /etc/bash.bashrc /etc/bash.bashrc.NOUSE</userinput></screen>
|
|
|
|
<para>When the <systemitem class="username">lfs</systemitem>
|
|
user is no longer needed (at the beginning of <xref
|
|
linkend="chapter-chroot-temporary-tools"/>), you may safely restore
|
|
<filename>/etc/bash.bashrc</filename> (if desired).</para>
|
|
|
|
<para>Note that the LFS Bash package we will build in
|
|
<xref linkend="ch-system-bash"/> is not configured to load or execute
|
|
<filename>/etc/bash.bashrc</filename>, so this file is useless on a
|
|
completed LFS system.</para>
|
|
</important>
|
|
|
|
<para>
|
|
For many modern systems with multiple processors (or cores) the
|
|
compilation time for a package can be reduced by performing a "parallel
|
|
make" by telling the make program how many processors are available via
|
|
a command line option or an environment variable. For instance, an Intel
|
|
Core i9-13900K processor has 8 P (performance) cores and
|
|
16 E (efficiency) cores, and a P core can simultaneously run two threads
|
|
so each P core are modeled as two logical cores by the Linux kernel.
|
|
As the result there are 32 logical cores in total. One obvious way to
|
|
use all these logical cores is allowing <command>make</command> to spawn
|
|
up to 32 build jobs. This can be done by passing the
|
|
<parameter>-j32</parameter> option to <command>make</command>:
|
|
</para>
|
|
|
|
<screen role='nodump'><userinput>make -j32</userinput></screen>
|
|
|
|
<para>
|
|
Or set the <envar>MAKEFLAGS</envar> environment variable and its
|
|
content will be automatically used by <command>make</command> as
|
|
command line options:
|
|
</para>
|
|
|
|
<screen role='nodump'><userinput>export MAKEFLAGS=-j32</userinput></screen>
|
|
|
|
<important>
|
|
<para>
|
|
Never pass a <parameter>-j</parameter> option without a number to
|
|
<command>make</command> or set such an option in
|
|
<envar>MAKEFLAGS</envar>. Doing so will allow <command>make</command>
|
|
to spawn infinite build jobs and cause system stability problems.
|
|
</para>
|
|
</important>
|
|
|
|
<para>
|
|
To use all logical cores available for building packages in
|
|
<xref linkend='chapter-cross-tools'/> and
|
|
<xref linkend='chapter-temporary-tools'/>, set <envar>MAKEFLAGS</envar>
|
|
now in <filename>.bashrc</filename>:
|
|
</para>
|
|
|
|
<screen><userinput>cat >> ~/.bashrc << "EOF"
|
|
<literal>export MAKEFLAGS=-j<replaceable>$(nproc)</replaceable></literal>
|
|
EOF</userinput></screen>
|
|
|
|
<para>
|
|
Replace <replaceable>$(nproc)</replaceable> with the number of logical
|
|
cores you want to use if you don't want to use all the logical cores.
|
|
</para>
|
|
|
|
<para>Finally, to ensure the environment is fully prepared for building the
|
|
temporary tools, force the <command>bash</command> shell to read
|
|
the new user profile:</para>
|
|
|
|
<screen><userinput>source ~/.bash_profile</userinput></screen>
|
|
|
|
</sect1>
|