lfs/prologue/architecture.xml

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<sect1 id="pre-architecture">
  <?dbhtml filename="architecture.html"?>

  <title>LFS Target Architectures</title>

<para>The primary target architectures of LFS are the AMD/Intel x86 (32-bit)
and x86_64 (64-bit) CPUs.  On the other hand, the instructions in this book are
also known to work, with some modifications, with the Power PC and ARM
CPUs.</para>

<para>For building LFS, the gain of building on a 64-bit system
compared to a 32-bit system is minimal.
For example, in a test build of LFS-9.1 on a Core i7-4790 CPU based system,
using 4 cores, the following statistics were measured:</para>

<screen><computeroutput>Architecture Build Time     Build Size
32-bit       239.9 minutes  3.6 GB
64-bit       233.2 minutes  4.4 GB</computeroutput></screen>

<para>As you can see, on the same hardware, the 64-bit build is only 3% faster
and is 22% larger than the 32-bit build. If you plan to use LFS as a LAMP
server, or a firewall, a 32-bit CPU may be largely sufficient. On the other
hand, several packages in BLFS now need more than 4GB of RAM to be built
and/or to run, so that if you plan to use LFS as a desktop, the LFS authors
recommend building on a 64-bit system.</para>

<para>The default 64-bit build that results from LFS is considered a
<quote>pure</quote> 64-bit system. That is, it supports 64-bit executables
only. Building a <quote>multi-lib</quote> system requires compiling many
applications twice, once for a 32-bit system and once for a 64-bit system.
This is not directly supported in LFS because it would interfere with the
educational objective of providing the instructions needed for a
straightforward base Linux system. Some LFS/BLFS editors maintain a fork
of LFS for multilib, which is accessible at <ulink
url="https://www.linuxfromscratch.org/~thomas/multilib/index.html"/>. But it
is an advanced topic.</para>

</sect1>