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git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@10121 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
58 lines
2.9 KiB
XML
58 lines
2.9 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../general.ent">
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%general-entities;
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]>
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<sect1 id="pre-architecture">
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<?dbhtml filename="architecture.html"?>
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<title>LFS Target Architectures</title>
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<para>The primary target architectures of LFS are the AMD/Intel x86 (32-bit)
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and x86_64 (64-bit) CPUs. On the other hand, the instructions in this book are
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also known to work, with some modifications, with the Power PC CPU. To build a
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system that utilizes one of these CPUs, the main prerequisite, in addition to
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those on the next few pages, is an existing Linux system such as an earlier LFS
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installation, Ubuntu, Red Hat/Fedora, SuSE, or other distribution that targets
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the architecture that you have. Also note that a 32-bit distribution can be
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installed and used as a host system on a 64-bit AMD/Intel computer.</para>
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<para>Some other facts about 64-bit systems need to be added here. When
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compared to a 32-bit system, the sizes of executable programs are slightly
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larger and the execution speeds are only slightly faster. For example, in a
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test build of LFS-6.5 on a Core2Duo CPU based system, the following statistics
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were measured:</para>
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<screen><computeroutput>Architecture Build Time Build Size
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32-bit 198.5 minutes 648 MB
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64-bit 190.6 minutes 709 MB</computeroutput></screen>
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<para>As you can see, the 64-bit build is only 4% faster and is 9% larger than
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the 32-bit build. The gain from going to a 64-bit system is relatively
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minimal. Of course, if you have more than 4GB of RAM or want to manipulate
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data that exceeds 4GB, the advantages of a 64-bit system are substantial.</para>
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<para>The default 64-bit build that results from LFS is considered a "pure"
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64-bit system. That is, it supports 64-bit executables only. Building a
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"multi-lib" system requires compiling many applications twice, once for a
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32-bit system and once for a 64-bit system. This is not directly supported in
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LFS because it would interfere with the educational objective of providing the
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instructions needed for a straightforward base Linux system. You can refer to
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the <ulink url="http://trac.cross-lfs.org/">Cross Linux From Scratch</ulink>
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project for this advanced topic.</para>
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<para>There is one last comment about 64-bit systems. There are some older
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packages that cannot currently be built in a "pure" 64-bit system or require
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specialized build instructions. Generally, these packages have some embedded
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32-bit specific assembly language instructions that fail when building on a
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64-bit system. This includes some Xorg drivers for some legacy video cards at
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<ulink url="http://xorg.freedesktop.org/releases/individual/driver/">
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http://xorg.freedesktop.org/releases/individual/driver/</ulink>. Many of these
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problems can be worked around, but may require some specialized procedures or
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patches.</para>
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</sect1>
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