Changes in prologue/architecture.xml [ac6e9a3:7739ad3]

File:

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

prologue/architecture.xml

@@ -11 +11 @@
   <title>LFS Target Architectures</title>
 
-<para>The primary target architectures of this LFS edition are LoongArch
-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
+<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 alternative CPUs, the main prerequisite, in
 addition to those on the next page, is an existing Linux system such as an
-earlier LFS installation, Loong Arch Linux, CLFS for LoongArch, Gentoo,
-Slackware, or other distribution that targets LoongArch.</para>
+earlier LFS installation, Ubuntu, Red Hat/Fedora, SuSE, or some other distribution
+that targets that architecture. (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 that results from this LFS edition is a
-<quote>pure</quote> lp64d system. That is, it supports executables with
-the lp64d ABI
+<para>The gain from building on a 64-bit system, as
+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 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 good enough. On the other
+hand, several packages in BLFS now need more than 4 GB of RAM to be built
+and/or to run; if you plan to use LFS as a desktop, the LFS authors
+recommend building a 64-bit system.</para>
+
+<para>The default 64-bit build that results from LFS is 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 multiple times, once for each ABI to be supported.
+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 minimal instructions needed for a
@@ -31 +46 @@
 of LFS, 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>
+that's an advanced topic.</para>
 
 </sect1>