Changes in prologue/architecture.xml [e5263d5:61707b1]

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• prologue/architecture.xml (modified) (2 diffs)

prologue/architecture.xml

@@ -11 +11 @@
   <title>LFS Target Architectures</title>
 
-<para>The target architectures of this LFS edition are ARM64 (sometimes
-called AArch64) CPUs.  On the other hand, the instructions in this book may
-work on 32-bit ARM CPUs with some modifications. To build a system that
-utilizes one of these CPUs, the main prerequisite, in addition to those on
-the next page, is an existing Linux system such as an earlier LFS
-installation, Ubuntu, Red Hat/Fedora, SuSE, or other distribution that
-targets the architecture that you have.</para>
+<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. To
+build a system that utilizes one of these CPUs, the main prerequisite, in
+addition to those on the next page, is an existing Linux system such as an
+earlier LFS installation, Ubuntu, Red Hat/Fedora, SuSE, or other distribution
+that targets the architecture that you have. Also note that a 32-bit
+distribution can be installed and used as a host system on a 64-bit AMD/Intel
+computer.</para>
 
-<para>The build results from this LFS edition 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
+<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
@@ -27 +45 @@
 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
-the multilib edition is for x86_64, and multilib is an advanced topic
-anyway.</para>
+url="https://www.linuxfromscratch.org/~thomas/multilib/index.html"/>. But it
+is an advanced topic.</para>
 
 </sect1>