Split Chapter 5 into three separate chapters.

Implement a new method of cross-building the LFS tool chain
and other tools to simplify the method of isolating the 
new system from the original host.  This will be the start of
LFS-10.0.

Move old trunk/BOOK to branches/old-trunk.



git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11946 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

1 files changed, 20 insertions, 212 deletions

diff --git a/chapter07/introduction.xml b/chapter07/introduction.xml
index cbc197a7b..1d53f6987 100644
--- a/chapter07/introduction.xml
+++ b/chapter07/introduction.xml
@@ -5,221 +5,29 @@
   %general-entities;
 ]>
 
-<sect1 id="ch-config-introduction" revision="sysv">
+<sect1 id="ch-tools-introduction-chroot">
   <?dbhtml filename="introduction.html"?>
 
   <title>Introduction</title>
 
-    <para>Booting a Linux system involves several tasks.  The process must
-    mount both virtual and real file systems, initialize devices, activate swap,
-    check file systems for integrity, mount any swap partitions or files, set
-    the system clock, bring up networking, start any daemons required by the
-    system, and accomplish any other custom tasks needed by the user.  This
-    process must be organized to ensure the tasks are performed in the correct
-    order but, at the same time, be executed as fast as possible.</para>
+  <para>This chapter shows how to build the last missing bits of the temporary
+  system: first, the tools needed by the build machinery of various packages,
+  then three packages needed to run tests.  Now that all circular dependencies
+  have been resolved, we can use a <quote>chroot</quote> environment,
+  completely isolated the host operating system used for the build, except
+  for the running kernel.</para>
+
+  <para>For proper operation of the isolated environment, some communication
+  with the running kernel must be established. This is done through the
+  so-called <emphasis>Virtual Kernel File Systems</emphasis>, which must be
+  mounted when entering the chroot environment. You may want to check
+  that they are mounted by issuing <command>findmnt</command>.</para>
+
+  <para>Until <xref linkend="ch-tools-chroot"/>, the commands must be
+  run as <systemitem class="username">root</systemitem>, with the
+  <envar>LFS</envar> variable set. After entering chroot, all commands
+  are run as root, fortunately without access to the OS of the computer
+  you built LFS on. Be careful anyway, as it is easy to destroy the whole
+  LFS system with badly formed commands.</para>
 
-<!--    <para>In the packages that were installed in Chapter&nbsp;6, there were two
-    different boot systems installed.  LFS provides the ability to easily
-    select which system the user wants to use and to compare and contrast the
-    two systems by actually running each system on the local computer.  The
-    advantages and disadvantages of these systems is presented below.</para>-->
-
-  <sect2 id='sysv-desc'>
-    <title>System V</title>
-
-    <para>System V is the classic boot process that has been used in Unix and
-    Unix-like systems such as Linux since about 1983.  It consists of a small
-    program, <command>init</command>, that sets up basic programs such as
-    <command>login</command> (via getty) and runs a script.  This script,
-    usually named <command>rc</command>,  controls the execution of a set of
-    additional scripts that perform the tasks required to initialize the
-    system.</para>
-
-    <para>The <command>init</command> program is controlled by the 
-    <filename>/etc/inittab</filename> file and is organized into run levels that
-    can be run by the user:</para>
-
-<literallayout>
-0 &mdash; halt
-1 &mdash; Single user mode
-2 &mdash; Multiuser, without networking
-3 &mdash; Full multiuser mode
-4 &mdash; User definable
-5 &mdash; Full multiuser mode with display manager
-6 &mdash; reboot
-</literallayout>
-
-    <para>The usual default run level is 3 or 5.</para>
-
-    <bridgehead renderas="sect3">Advantages</bridgehead>
-
-    <itemizedlist>
-      <listitem>
-          <para>Established, well understood system.</para>
-      </listitem>
-
-      <listitem>
-          <para>Easy to customize.</para>
-      </listitem>
-
-    </itemizedlist>
-
-
-    <bridgehead renderas="sect3">Disadvantages</bridgehead>
-
-    <itemizedlist>
-      <listitem>
-          <para>Slower to boot.  A medium speed base LFS system 
-          takes 8-12 seconds where the boot time is measured from the 
-          first kernel message to the login prompt.  Network 
-          connectivity is typically established about 2 seconds 
-          after the login prompt.</para>
-      </listitem>
-
-      <listitem>
-          <para>Serial processing of boot tasks. This is related to the previous
-          point.  A delay in any process such as a file system check, will
-          delay the entire boot process.</para>
-      </listitem>
-
-      <listitem>
-          <para>Does not directly support advanced features like
-          control groups (cgroups), and per-user fair share scheduling.</para>
-      </listitem>
-
-      <listitem>
-          <para>Adding scripts requires manual, static sequencing decisions.</para>
-      </listitem>
-
-    </itemizedlist>
-
-  </sect2>
-<!--
-  <sect2 id='sysd-desc'>
-    <title>Systemd</title>
-
-    <para>Systemd is a group of interconnected programs that handles system and
-    individual process requests.  It provides a dependency system between
-    various entities called "units".  It automatically addresses dependencies
-    between units and can execute several startup tasks in parallel.  It
-    provides login, inetd, logging, time, and networking services. </para>
-
-    <bridgehead renderas="sect3">Advantages</bridgehead>
-
-    <itemizedlist>
-      <listitem>
-          <para>Used on many established distributions by default.</para>
-      </listitem>
-
-      <listitem>
-          <para>There is extensive documentation. 
-          See <ulink url="http://www.freedesktop.org/wiki/Software/systemd/"/>.</para>
-      </listitem>
-
-      <listitem>
-          <para>Parallel execution of boot processes. A medium speed
-          base LFS system takes 6-10 seconds from kernel start to a 
-          login prompt.  Network connectivity is typically established 
-          about 2 seconds after the login prompt.  More complex startup
-          procedures may show a greater speedup when compared to System V.</para>
-      </listitem>
-
-      <listitem>
-          <para>Implements advanced features such as control groups to 
-          manage related processes.</para>
-      </listitem>
-
-      <listitem>
-          <para>Maintains backward compatibility with System V programs 
-          and scripts.</para>
-      </listitem>
-    </itemizedlist>
-
-    <bridgehead renderas="sect3">Disadvantages</bridgehead>
-
-    <itemizedlist>
-      <listitem>
-          <para>There is a substantial learning curve.</para>
-      </listitem>
-
-      <listitem>
-          <para>Some advanced features such as dbus or cgroups cannot be
-          disabled if they are not otherwise needed.</para>
-      </listitem>
-
-      <listitem>
-          <para>Although implemented as several executable programs
-          the user cannot choose to implement only the portions desired.</para>
-      </listitem>
-
-      <listitem>
-          <para>Due to the nature of using compiled programs, systemd is
-          more difficult to debug.</para>
-      </listitem>
-
-      <listitem>
-          <para>Logging is done in a binary format.  Extra tools must
-          be used to process logs or additional processes must be implemented
-          to duplicate traditional logging programs.</para>
-      </listitem>
-
-    </itemizedlist>
-
-  </sect2>
--->
-<!--
-  <sect2 id='sysv'>
-    <title>Selecting a Boot Method</title>
-
-    <para>Selecting a boot method in LFS is relatively easy.  
-    Both systems are installed side-by-side.  The only task needed is to
-    ensure the files that are needed by the system have the correct names.
-    The following scripts do that.</para>
-
-<screen><userinput remap="install">cat &gt; /usr/sbin/set-systemd &lt;&lt; "EOF"
-#! /bin/bash
-
-ln -svfn init-systemd   /sbin/init
-ln -svfn init.d-systemd /etc/init.d
-
-for tool in halt poweroff reboot runlevel shutdown telinit; do
-  ln -sfvn  ${tool}-systemd   /sbin/${tool}
-  ln -svfn  ${tool}-systemd.8 /usr/share/man/man8/${tool}.8
-done
-
-echo "Now reboot with /sbin/reboot-sysv"
-EOF
-
-chmod 0744 /usr/sbin/set-systemd
-
-cat &gt; /usr/sbin/set-sysv &lt;&lt; "EOF"
-#! /bin/bash
-
-ln -sfvn init-sysv    /sbin/init
-ln -svfn init.d-sysv  /etc/init.d
-
-for tool in halt poweroff reboot runlevel shutdown telinit; do
-  ln -sfvn  ${tool}-sysv   /sbin/${tool}
-  ln -svfn  ${tool}-sysv.8 /usr/share/man/man8/${tool}.8
-done
-
-echo "Now reboot with /sbin/reboot-systemd"
-EOF
-
-chmod 0744 /usr/sbin/set-sysv</userinput></screen>
-
-  <note><para>The comment about the correct command to reboot in the 
-  above scripts is correct.  The reboot command for the current boot
-  system must be used after the script changes the default reboot command.
-  </para></note>
-
-  <para>Now set the desired boot system.  The default is System V:</para>
-
-<screen><userinput remap="install">/usr/sbin/set-sysv</userinput></screen>
-
-  <para>Changing the boot system can be done at any time by running the 
-  appropriate script above and rebooting.</para>
-
-  </sect2>
--->
 </sect1>