This book is a highly experimental port of LFS to 64-bit little-endian MIPS (MIPS64 EL) architecture. The instructions are only tested on a Loongson-3A4000 based board. On the other hand, the instructions in this book should work on other MIPS64 EL 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, Fedora, or other distribution that targets the architecture that you have.
The build that results from the book is considered a “pure” 64-bit system. That is, it supports 64-bit executables only. Building a “multi-lib” 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 on AMD64, which is accessible at http://www.linuxfromscratch.org/~thomas/multilib/index.html. But it is an advanced topic.