Rearrange "How things are going to be done" section. Simplify seds in "Locking in Glibc" and "Re-adjusting the toolchain" sections. Miscellaneous other fixes.

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@2931 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
This commit is contained in:
Greg Schafer 2003-10-07 00:41:12 +00:00
parent 04a335156f
commit f57e3d1ad9
8 changed files with 49 additions and 52 deletions

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@ -95,6 +95,10 @@
</itemizedlist>
</para></listitem>
<listitem><para>October 6th, 2003 [greg]: Simplify seds in "Locking in Glibc"
and "Re-adjusting the toolchain" sections. Rearrange "How things are going to be
done" section.</para></listitem>
<listitem><para>October 5th, 2003 [greg]: Chapter 5: Add new section "Toolchain
technical notes". Integrate and scale back the old "Why we use static linking"
section. Closes Bug 658.</para></listitem>

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@ -9,15 +9,15 @@ programs like a compiler, linker and shell to build the new system. Normally
all the required tools are available if you selected <quote>development</quote>
as one of the options when you installed your distribution.</para>
<para>In Chapter 3 you will first create a new Linux native partition and
filesystem, the place where your new LFS system will be compiled and installed.
Then in Chapter 4 you download all the packages and patches required to build
an LFS system, and store them on the new filesystem.</para>
<para>In Chapter 3 you will first create a new Linux native partition and file
system, the place where your new LFS system will be compiled and installed. Then
in Chapter 4 you download all the packages and patches required to build an LFS
system, and store them on the new file system.</para>
<para>Chapter 5 will then discuss the installation of a number of packages that
will form the basic development suite (or tool-set) 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
<para>Chapter 5 will then discuss the installation of a number of packages that
will form the basic development suite (or toolchain) 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
@ -25,35 +25,17 @@ 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>
pass. 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-independent 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-independent 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>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 as possible from your host makes it into
your brand new 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 has the potential to cause
problems for you down the road. The host's Glibc is usually an unknown
quantity and might even 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 contain calls to the
<emphasis>getpwuid()</emphasis> function crash when run on a Glibc-2.3.x based
system. Seeing as we are about to build a Glibc-2.3.x based system, we need to
shield ourselves from problems of this nature. The procedure employed in
Chapter 5 achieves this goal. 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>You may be asking yourself <quote>that seems like a lot of work, just to
get away from my host distribution?</quote>. A full technical and in-depth
explanation is provided at the start of Chapter 5, including some notes on the
differences between statically and dynamically linked programs.</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

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@ -155,7 +155,7 @@ to continue on.</para>
<note><para>At this point it is strongly recommended to repeat the sanity check
we performed earlier in the chapter. Refer back to the "Locking in" Glibc section
and repeat the check. If the results are wrong then most likely, you forgot to
apply the abovementioned GCC Specs patch.</para></note>
apply the above mentioned GCC Specs patch.</para></note>
</sect2>

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@ -23,16 +23,20 @@ Binutils build and source directories.</para>
to the new dynamic linker. A simple sed will accomplish this:</para>
<para><screen><userinput>SPECFILE=/tools/lib/gcc-lib/*/*/specs
sed -e 's@/lib/ld.so.1@/tools/lib/ld.so.1@g' \
&nbsp;&nbsp;&nbsp;&nbsp;-e 's@/lib/ld-linux.so.2@/tools/lib/ld-linux.so.2@g' \
sed -e 's@/lib/ld-linux.so.2@/tools/lib/ld-linux.so.2@g' \
&nbsp;&nbsp;&nbsp;&nbsp;$SPECFILE > tempspecfile
mv tempspecfile $SPECFILE
unset SPECFILE</userinput></screen></para>
<para>We recommend that you cut-and-paste the above rather than try and type it
all in. Or you can edit the specs file by hand if you want to: just replace
"/lib/ld-linux.so.2" with "/tools/lib/ld-linux.so.2" and "/lib/ld.so.1" with
"/tools/lib/ld.so.1".</para>
<para>We recommend that you cut-and-paste the above rather than try and type it
all in. Or you can edit the specs file by hand if you want to: just replace any
occurrence of "/lib/ld-linux.so.2" with "/tools/lib/ld-linux.so.2".</para>
<important><para>If you are working on a platform where the name of the dynamic
linker is something other than <filename>ld-linux.so.2</filename>, you
<emphasis>must</emphasis> substitute <filename>ld-linux.so.2</filename> with the
name of your platform's dynamic linker in the above commands. Refer back to the
"Toolchain technical notes" section if necessary.</para></important>
<para>Lastly, there is a possibility that some include files from the host
system have found their way into GCC's private include dir. This can happen

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@ -122,8 +122,8 @@ adjusted ld, which has a hard-wired search path limited to
file to point to our new dynamic linker in
<filename class="directory">/tools/lib</filename>. This last step is
<emphasis>vital</emphasis> to the whole process. As mentioned above, a
hard-wired path to a dynamic linker is embedded into every executable binary.
You can inspect this by running:
hard-wired path to a dynamic linker is embedded into every ELF shared
executable. You can inspect this by running:
<userinput>`readelf -l &lt;name of binary&gt; | grep interpreter`</userinput>.
By amending the GCC specs file, we are ensuring that every program compiled from
here through the end of Chapter 5 will use our new dynamic linker in

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@ -17,8 +17,8 @@ adjusted linker by running the following from within the
<note><para>If you somehow missed the earlier warning to retain the Binutils
source and build directories from the second pass in Chapter 5 or otherwise
accidentally deleted them or just don't have access to them, don't worry, all is
not lost. Just ignore this step. The result will be that the next package,
Binutils, will link against the Glibc libraries in
not lost. Just ignore the above command. The result will be that the next
package, Binutils, will link against the Glibc libraries in
<filename class="directory">/tools</filename> rather than
<filename class="directory">/usr</filename>. This is not ideal, however, our
testing has shown that the resulting Binutils program binaries should be
@ -41,8 +41,7 @@ to the new dynamic linker. Just like earlier on, we use a sed to accomplish
this:</para>
<para><screen><userinput>SPECFILE=/tools/lib/gcc-lib/*/*/specs
sed -e 's@/tools/lib/ld.so.1@/lib/ld.so.1@g' \
&nbsp;&nbsp;&nbsp;&nbsp;-e 's@/tools/lib/ld-linux.so.2@/lib/ld-linux.so.2@g' \
sed -e 's@/tools/lib/ld-linux.so.2@/lib/ld-linux.so.2@g' \
&nbsp;&nbsp;&nbsp;&nbsp;$SPECFILE > newspecfile
mv newspecfile $SPECFILE
unset SPECFILE</userinput></screen></para>
@ -51,6 +50,12 @@ unset SPECFILE</userinput></screen></para>
before, it is a good idea to check the specs file to ensure the intended
changes were actually made.</para>
<important><para>If you are working on a platform where the name of the dynamic
linker is something other than <filename>ld-linux.so.2</filename>, you
<emphasis>must</emphasis> substitute <filename>ld-linux.so.2</filename> with the
name of your platform's dynamic linker in the above commands. Refer back to the
"Toolchain technical notes" section if necessary.</para></important>
<caution><para>It is imperative at this point to stop and ensure that the
basic functions (compiling and linking) of the adjusted toolchain are working
as expected. For this we are going to perform a simple sanity check:</para>

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@ -24,7 +24,9 @@ compilers. Instructions for building these can be found at
patch -Np1 -i ../gcc-&gcc-suppress-libiberty-patch-version;.patch</userinput></screen></para>
<para>The second patch here suppresses the installation of libiberty from GCC,
as we will use the one provided by binutils instead.</para>
as we will use the one provided by binutils instead. Be careful
<emphasis>not</emphasis> to apply the GCC specs patch from Chapter 5
here.</para>
<para>The GCC documentation recommends building GCC outside of the source
directory in a dedicated build directory:</para>

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@ -3,8 +3,8 @@
"/usr/share/docbook/docbookx.dtd" [
<!ENTITY version "20031006">
<!ENTITY releasedate "October 6th, 2003">
<!ENTITY version "20031007">
<!ENTITY releasedate "October 7th, 2003">
<!ENTITY nbsp " ">
<!ENTITY ftp-root "ftp://ftp.linuxfromscratch.org">