lfs-book/chapter07/introduction.xml

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<sect1 id="ch-tools-introduction-chroot">
  <?dbhtml filename="introduction.html"?>

  <title>Introduction</title>

  <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
  from the computer 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>ls $LFS/dev</command>,
  <command>ls $LFS/proc</command>, or <command>ls $LFS/sys</command>.
  Note that mounting the virtual kernel file systems must be done
  <emphasis>each time you want to enter the chroot
  environment</emphasis>.</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 build LFS on. Be careful anyway, as it is easy to destroy the whole
  LFS system with badly formed commands.</para>

</sect1>