|
|
@@ -2,63 +2,87 @@
|
|
|
<title>How things are going to be done</title>
|
|
|
<?dbhtml filename="how.html" dir="chapter01"?>
|
|
|
|
|
|
-<para>You are going to build the LFS system by using a previously installed
|
|
|
-Linux distribution such as Debian, Mandrake, Red Hat, etc.
|
|
|
-The existing Linux system will be used as a starting point, because you
|
|
|
-will need tools like a compiler, linker, text editor, and other development
|
|
|
-tools to build the system. Ordinarily, the required tools are available by
|
|
|
-default if you selected "development" as one of your installation options
|
|
|
-when you installed your Linux distribution.</para>
|
|
|
+<para>You are going to build your LFS system by using a previously installed
|
|
|
+Linux distribution such as Debian, Mandrake, Red Hat, etc. The existing Linux
|
|
|
+system (host) will be used as a starting point, because you will need programs
|
|
|
+like a compiler, linker, text editor, and other development tools to build the
|
|
|
+new system. Ordinarily, the required tools are available by default if you
|
|
|
+selected <quote>development</quote> as one of your installation options when
|
|
|
+you installed your Linux distribution.</para>
|
|
|
|
|
|
-<para>After you have downloaded the packages that make up an LFS system,
|
|
|
-you will create a new Linux native partition and filesystem. Here is where
|
|
|
-the LFS system will be compiled and installed onto.</para>
|
|
|
+<para>After you have downloaded the packages that make up a LFS system, you
|
|
|
+will create a new Linux native partition and filesystem. This new Linux
|
|
|
+partition and filesystem is where your new LFS system will be compiled and
|
|
|
+installed onto.</para>
|
|
|
|
|
|
-<para>The next step, Chapter 5, will discuss the installation of a number
|
|
|
-of packages that will form the basic development suite which is used to
|
|
|
-build the actual system. Some of these packages are needed to resolve
|
|
|
-circular dependencies. For example, to compile a compiler you need a
|
|
|
+<para>Chapter 5 will then discuss the installation of a number of packages that
|
|
|
+will form the basic development suite (or toolset) which is used to build the
|
|
|
+actual system in Chapter 6. Some of these packages are needed to resolve
|
|
|
+circular dependencies. For example, to compile a compiler you need a
|
|
|
compiler.</para>
|
|
|
|
|
|
-<para>The first thing to be done in Chapter 5 is build a first pass of the
|
|
|
-toolchain, which is made up of Binutils and GCC. The programs from these
|
|
|
-packages will be linked statically in order for them to be used independently
|
|
|
-of the host system. The second thing to do is build Glibc, the C library.
|
|
|
-Glibc will be built with the toolchain programs we just built in the first
|
|
|
+<para>The first thing to be done in Chapter 5 is build a first pass of the
|
|
|
+toolchain, which is made up of Binutils and GCC. The programs from these
|
|
|
+packages will be linked statically in order for them to be used independently
|
|
|
+of the host system. The second thing to do is build Glibc, the C library. Glibc
|
|
|
+will be compiled by the toolchain programs we just built in the first
|
|
|
pass.</para>
|
|
|
|
|
|
-<para>The next thing to do is build a second pass of the toolchain. This
|
|
|
-time the toolchain will be dynamically linked against the newly built Glibc.
|
|
|
-The remaining Chapter 5 packages are all built using this second pass
|
|
|
-toolchain and dynamically linked against the new Glibc. When this is done,
|
|
|
-the LFS installation process will no longer depend on the host distribution,
|
|
|
-with the exception of the running kernel.</para>
|
|
|
+<para>The third thing to do is build a second pass of the toolchain. This time
|
|
|
+the toolchain will be dynamically linked against the newly built Glibc. The
|
|
|
+remaining Chapter 5 packages are all built using this second pass toolchain and
|
|
|
+dynamically linked against the new host independant Glibc. When this is done,
|
|
|
+the LFS installation process will no longer depend on the host distribution,
|
|
|
+with the exception of the running kernel. This is known as <quote>self
|
|
|
+contained</quote> and <quote>self hosted</quote>. There is a discussion of the
|
|
|
+differences between statically and dynamically linked programs at the beginning
|
|
|
+of Chapter 5.</para>
|
|
|
|
|
|
-<para>In Chapter 6 the real LFS system will be built. The
|
|
|
-chroot (change root) program is used to enter a virtual environment and
|
|
|
-start a new shell whose root directory will be set to the LFS partition.
|
|
|
-This is very similar to rebooting and instructing the kernel to mount the
|
|
|
-LFS partition as the root partition. The reason that you don't actually
|
|
|
-reboot, but instead chroot, is that creating a bootable system requires
|
|
|
-additional work which isn't necessary. As well, chrooting allows you
|
|
|
-to continue using the host while LFS is being built. While software is
|
|
|
-being installed you can simply switch to a different VC (Virtual Console)
|
|
|
-or X desktop and continue using the computer as you normally would.</para>
|
|
|
+<para>You may be asking yourself <quote>that seems like a lot of work, just to
|
|
|
+get away from my host distribution</quote>. Let us take a few minutes to
|
|
|
+discuss this question. The work involved in building the packages in Chapter 5
|
|
|
+is to ensure that as little information from your host makes it into your new
|
|
|
+pristine LFS system. When you build the first two packages in Chapter 5,
|
|
|
+Binutils and GCC, they will be compiled statically. This means that the
|
|
|
+version of the C library on your host distribution will be embedded inside all
|
|
|
+the binary programs you just compiled. This will cause problems for you down
|
|
|
+the road (they have been well documented). The host's Glibc is usually an
|
|
|
+unknown quantity and can contain bugs or anything else we don't know about
|
|
|
+until it is too late. A well known issue is that statically linked binaries
|
|
|
+compiled on a Glibc-2.2.x based system that then contain calls to the
|
|
|
+getpwuid() function crash when run on a glibc-2.3.x based system. You are
|
|
|
+about to build a Glibc-2.3.x based system. You do not want to build something
|
|
|
+that is going to crash do you? Finally, the Glibc Autoconf tests produce
|
|
|
+different results depending on whether an existing Glibc is found on the host
|
|
|
+distribution. This can lead to inconsistencies and encourages hacks and
|
|
|
+workarounds. With all these things in mind, you can see that the extra effort
|
|
|
+to compile Binutils and GCC twice is well worth it.</para>
|
|
|
|
|
|
-<para>When all the software from Chapter 6 is installed, the temporary
|
|
|
-tools built in Chapter 5 will be removed. Chapters 7, 8 and 9 will finalize
|
|
|
-the installation. The bootscripts are setup in Chapter 7, the kernel and
|
|
|
-boot loader are setup in Chapter 8 and Chapter 9 has some pointers to help
|
|
|
-you after you finish with the book. Then, finally, you reboot the system
|
|
|
-into the new LFS system.</para>
|
|
|
+<para>In Chapter 6 your real LFS system will be built. The chroot (change root)
|
|
|
+program is used to enter a virtual environment and start a new shell whose root
|
|
|
+directory will be set to the LFS partition. This is very similar to rebooting
|
|
|
+and instructing the kernel to mount the LFS partition as the root partition.
|
|
|
+The reason that you don't actually reboot, but instead chroot, is that creating
|
|
|
+a bootable system requires additional work which isn't necessary. As well,
|
|
|
+chrooting allows you to continue using the host while LFS is being built.
|
|
|
+While software is being installed you can simply switch to a different VC
|
|
|
+(Virtual Console) or X desktop and continue using the computer as you normally
|
|
|
+would.</para>
|
|
|
|
|
|
-<para>This is the process in a nutshell. Detailed information on the steps
|
|
|
-you will take are discussed in the chapters and package descriptions as you
|
|
|
-progress through them. If something isn't completely clear now, don't
|
|
|
-worry, everything will fall into place soon.</para>
|
|
|
+<para>When all the software from Chapter 6 is installed, the temporary tools
|
|
|
+built in Chapter 5 will be removed. Chapters 7, 8 and 9 will finalize the
|
|
|
+installation. The bootscripts are setup in Chapter 7, the kernel and boot
|
|
|
+loader are setup in Chapter 8 and Chapter 9 has some pointers to help you after
|
|
|
+you finish with the book. Then, finally, you reboot your computer into your
|
|
|
+new LFS system.</para>
|
|
|
|
|
|
-<para>Please read Chapter 2 carefully as it explains a few important things
|
|
|
-you should be aware of before you begin to work through Chapters 5 and
|
|
|
+<para>This is the process in a nutshell. Detailed information on the steps you
|
|
|
+will take are discussed in the chapters and package descriptions as you
|
|
|
+progress through them. If something isn't completely clear now, don't worry,
|
|
|
+everything will fall into place soon.</para>
|
|
|
+
|
|
|
+<para>Please read Chapter 2 carefully as it explains a few important things you
|
|
|
+should be aware of before you begin to work through Chapters 5 and
|
|
|
beyond.</para>
|
|
|
|
|
|
</sect1>
|
James Robertson