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  1. <?xml version="1.0" encoding="ISO-8859-1"?>
  2. <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  3. <!ENTITY % general-entities SYSTEM "../general.ent">
  4. %general-entities;
  5. ]>
  6. <sect1 id="ch-scatter-how">
  7. <title>How to Build an LFS System</title>
  8. <?dbhtml filename="how.html"?>
  9. <para>The LFS system will be built by using a previously installed
  10. Linux distribution (such as Debian, Mandrake, Red Hat, or SuSE). This
  11. existing Linux system (the host) will be used as a starting point to
  12. provide necessary programs, including a compiler, linker, and shell,
  13. to build the new system. Select the <quote>development</quote> option
  14. during the distribution installation to be able to access these
  15. tools.</para>
  16. <para><xref linkend="chapter-partitioning"/> of this book describes how
  17. to create a new Linux native partition and file system, the place
  18. where the new LFS system will be compiled and installed. <xref
  19. linkend="chapter-getting-materials"/> explains which packages and
  20. patches need to be downloaded to build an LFS system and how to store
  21. them on the new file system. <xref linkend="chapter-final-preps"/>
  22. discusses the setup for an appropriate work environment. Please read
  23. <xref linkend="chapter-final-preps"/> carefully as it explains several
  24. important issues the developer should be aware of before beginning to
  25. work through <xref linkend="chapter-temporary-tools"/> and
  26. beyond.</para>
  27. <para><xref linkend="chapter-temporary-tools"/> explains the
  28. installation of a number of packages that will form the basic
  29. development suite (or toolchain) which is used to build the actual
  30. system in <xref linkend="chapter-building-system"/>. Some of these
  31. packages are needed to resolve circular dependencies&mdash;for example,
  32. to compile a compiler, you need a compiler.</para>
  33. <para><xref linkend="chapter-temporary-tools"/> also shows the user how
  34. to build a first pass of the toolchain, including Binutils and GCC
  35. (first pass basically means these two core packages will be
  36. re-installed a second time). The programs from these packages will be
  37. linked statically in order to be used independently of the host
  38. system. The next step is to build Glibc, the C library. Glibc will be
  39. compiled by the toolchain programs built in the first pass. Then, a
  40. second pass of the toolchain will be built. This time, the toolchain
  41. will be dynamically linked against the newly built Glibc. The
  42. remaining <xref linkend="chapter-temporary-tools"/> packages are built
  43. using this second pass toolchain. When this is done, the LFS
  44. installation process will no longer depend on the host distribution,
  45. with the exception of the running kernel.</para>
  46. <para>While this may initially seem like a lot of work to get away
  47. from a host distribution, a full technical explanation is provided at
  48. the beginning of <xref linkend="chapter-temporary-tools"/>,
  49. including notes on the differences between
  50. statically and dynamically-linked programs.</para>
  51. <para>In <xref linkend="chapter-building-system"/>, the full LFS system is
  52. built. The chroot (change root) program is used to enter a virtual
  53. environment and start a new shell whose root directory will be set to
  54. the LFS partition. This is very similar to rebooting and instructing
  55. the kernel to mount the LFS partition as the root partition. The
  56. system does not actually reboot, but instead chroots because creating a
  57. bootable system requires additional work which is not necessary just
  58. yet. The major advantage is that <quote>chrooting</quote> allows the
  59. builder to continue using the host while LFS is being built. While
  60. waiting for package compilation to complete, a user can switch to a
  61. different virtual console (VC) or X desktop and continue using the
  62. computer as normal.</para>
  63. <para>To finish the installation, the bootscripts are set up in <xref
  64. linkend="chapter-bootscripts"/>, and the kernel and boot loader are set
  65. up in <xref linkend="chapter-bootable"/>. <xref
  66. linkend="chapter-finalizing"/> contains information on furthering the
  67. LFS experience beyond this book. After the steps in this book have
  68. been implemented, the computer will be ready to reboot into the new
  69. LFS system.</para>
  70. <para>This is the process in a nutshell. Detailed information on each
  71. step is discussed in the following chapters and package descriptions.
  72. Items that may seem complicated will be clarified, and everything will
  73. fall into place as the developer embarks on the LFS adventure.</para>
  74. </sect1>