[3f8be484] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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| 4 | <!ENTITY % general-entities SYSTEM "../../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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| 7 |
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| 8 | <sect1 id="ch-intro-how">
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| 9 | <?dbhtml filename="how.html"?>
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| 10 |
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| 11 | <title>How to Build an LFS System</title>
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| 12 |
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| 13 | <para>The LFS system will be built by using a previously installed
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| 14 | Linux distribution (such as Debian, Mandrake, Red Hat, or SuSE). This
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| 15 | existing Linux system (the host) will be used as a starting point to
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| 16 | provide necessary programs, including a compiler, linker, and shell,
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| 17 | to build the new system. Select the <quote>development</quote> option
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| 18 | during the distribution installation to be able to access these
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| 19 | tools.</para>
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| 20 |
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| 21 | <para>As an alternative to installing an entire separate distribution
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[39a9546] | 22 | onto your machine, you may wish to
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[3f8be484] | 23 | use the Linux From Scratch LiveCD. The CD works well as a host system,
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| 24 | providing all the tools you need to successfully follow the instructions
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| 25 | in this book. Additionally, it contains all the source packages, patches
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| 26 | and a copy of this book. So once you have the CD, no network connection
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| 27 | or additional downloads are necessary. For more information about the
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| 28 | LFS LiveCD or to download a copy, visit <ulink url="&livecd-root;"/></para>
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| 29 |
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| 30 | <!-- -->
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[8659630] | 31 | <para>THE TEXT BELOW NEEDS TO BE REWRITTEN</para>
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[3f8be484] | 32 |
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| 33 | <para><xref linkend="chapter-partitioning"/> of this book describes how
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| 34 | to create a new Linux native partition and file system, the place
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| 35 | where the new LFS system will be compiled and installed. <xref
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| 36 | linkend="chapter-getting-materials"/> explains which packages and
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| 37 | patches need to be downloaded to build an LFS system and how to store
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| 38 | them on the new file system. <xref linkend="chapter-final-preps"/>
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| 39 | discusses the setup for an appropriate working environment. Please read
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| 40 | <xref linkend="chapter-final-preps"/> carefully as it explains several
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| 41 | important issues the developer should be aware of before beginning to
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[8659630] | 42 | work through <xref linkend="chapter-cross-tools"/> and
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[3f8be484] | 43 | beyond.</para>
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| 44 |
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[5da8aa0] | 45 | <para><xref linkend="chapter-cross-tools"/> explains the installation of
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| 46 | cross-compile tools which will be built on the host but be able to compile
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| 47 | programs that run on the target machine. These cross-compile tools will
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| 48 | be used to create a temporary, minimal system that will be the basis for
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| 49 | building the final LFS system. Some of these packages are needed to resolve
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| 50 | circular dependencies—for example, to compile a compiler, you need a
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| 51 | compiler.</para>
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| 52 |
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| 53 | <para>The process of building cross-compile tools first involves installing
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| 54 | binutils into /cross-tools, so that the linker can be used with the building
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| 55 | of everything else in the temp-system. GCC is then compiled statically and
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| 56 | installed into /cross-tools, and this cross-compiler is used to build glibc
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| 57 | into /tools for the temp-system. The GCC cross-compiler is then rebuilt
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| 58 | dynamically - this final cross-compiler is what will be used to build the
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| 59 | rest of the temporary system. When this is done, the CLFS installation
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| 60 | process will no longer depend on the host distribution, with the exception
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| 61 | of the running kernel.
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| 62 | <!-- still needs some work - needs to provide a better technical
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| 63 | explanation, especially the reasoning for compiling gcc statically then dynamically... --></para>
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| 64 |
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| 65 | <para>The packages in <xref linkend="chapter-temp-system"/> are then built
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| 66 | using the cross-compiled tools in /cross-tools, and linked against the
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| 67 | C library that was installed during the building of the cross-tools.</para>
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[3f8be484] | 68 |
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| 69 | <para>This effort to isolate the new system from the host distribution
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| 70 | may seem excessive, but a full technical explanation is provided at the
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[134ba96] | 71 | beginning of <xref linkend="chapter-temp-system"/>.</para>
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[3f8be484] | 72 |
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| 73 | <para>In <xref linkend="chapter-building-system"/>, the full LFS system is
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[5da8aa0] | 74 | built. Depending on the system you are cross-compiling for, either you will
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| 75 | boot the minimal temp-system on the target machine, or chroot into it.</para>
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| 76 |
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| 77 | <para>The <command>chroot</command> (change root) program is used to enter
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[3f8be484] | 78 | a virtual environment and start a new shell whose root directory will be set
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| 79 | to the LFS partition. This is very similar to rebooting and instructing the
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[5da8aa0] | 80 | kernel to mount the LFS partition as the root partition.
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[3f8be484] | 81 | The major advantage is that <quote>chrooting</quote> allows the builder to
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| 82 | continue using the host while LFS is being built. While waiting for package
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| 83 | compilation to complete, a user can switch to a different virtual console
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| 84 | (VC) or X desktop and continue using the computer as normal.</para>
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| 85 |
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[5da8aa0] | 86 | <para>Some systems cannot be built by chrooting so they must be booted instead. Generally, if you building for a different arch than the host system, you must reboot because the kernel will likely not support the target machine. Booting involves installing a few additional packages that are needed for bootup, installing bootscripts, and building a miminal kernel.</para>
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| 87 |
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[3f8be484] | 88 | <para>To finish the installation, the LFS-Bootscripts are set up in <xref
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| 89 | linkend="chapter-bootscripts"/>, and the kernel and boot loader are set
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| 90 | up in <xref linkend="chapter-bootable"/>. <xref
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| 91 | linkend="chapter-finalizing"/> contains information on furthering the
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| 92 | LFS experience beyond this book. After the steps in this book have
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| 93 | been implemented, the computer will be ready to reboot into the new
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| 94 | LFS system.</para>
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| 95 | <!-- -->
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| 96 |
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| 97 | <para>This is the process in a nutshell. Detailed information on each
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| 98 | step is discussed in the following chapters and package descriptions.
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| 99 | Items that may seem complicated will be clarified, and everything will
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| 100 | fall into place as the reader embarks on the LFS adventure.</para>
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| 101 |
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| 102 | </sect1>
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