gronod/lfs
1
0
Fork 0
mirror of https://git.linuxfromscratch.org/lfs.git synced 2025-03-06 06:14:47 +00:00
Code Issues Packages Projects Releases Wiki Activity

Correct and clarify toolchain explanatory notes. Fixes #2461.

Browse Source 
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@9021 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
This commit is contained in:
Matthew Burgess 2009-07-29 20:46:21 +00:00
parent 420a2a2123
commit af9063d6b4
2 changed files with 44 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
chapter01/changelog.xml
View File

@ -39,6 +39,11 @@
<listitem>
<para>2009-07-29</para>
<itemizedlist>
<listitem>
<para>[matthew] - Correct and clarify some of the explanatory text in
the toolchain technical notes. Fixes
<ulink url="&lfs-ticket-root;2461">#2461</ulink>.</para>
</listitem>
<listitem>
<para>[bdubbs] - Updated Acknowledgements.
Fixes

78
chapter05/toolchaintechnotes.xml
View File

@ -17,13 +17,13 @@
to at any time during the process.</para>
<para>The overall goal of <xref linkend="chapter-temporary-tools"/> is to
provide a temporary environment that can be chrooted into and from which can be
produced a clean, trouble-free build of the target LFS system in <xref
linkend="chapter-building-system"/>. Along the way, we separate the new system
from the host system as much as possible, and in doing so, build a
self-contained and self-hosted toolchain. It should be noted that the build
process has been designed to minimize the risks for new readers and provide
maximum educational value at the same time.</para>
provide a temporary environment that can be chrooted into,
where a clean, trouble-free build of the target LFS system in <xref
linkend="chapter-building-system"/> can be produced. Along the way, we
separate the new system from the host system as much as possible, and in
doing so, build a self-contained and self-hosted toolchain.
The build process has been designed to minimize the risks for new
readers and to provide the most educational value at the same time.</para>
<important>
<para>Before continuing, be aware of the name of the working platform,
@ -54,11 +54,13 @@
<itemizedlist>
<listitem>
<para>Slightly adjusting the name of the working platform ensures that
the first build of Binutils and GCC produces a compatible cross-linker
and cross-compiler. Instead of producing binaries for another architecture,
the cross-linker and cross-compiler will produce binaries compatible with
the current hardware.</para>
<para>Slightly adjusting the name of the working platform, by changing the
&quot;vendor&quot; field target triplet by way of the
<envar>LFS_TGT</envar> variable, ensures that the first build of Binutils
and GCC produces a compatible cross-linker and cross-compiler. Instead of
producing binaries for another architecture, the cross-linker and
cross-compiler will produce binaries compatible with the current
hardware.</para>
</listitem>
<listitem>
<para>The temporary libraries are cross-compiled. This removes all
@ -98,9 +100,8 @@
<para>The next package installed is GCC. An example of what can be
seen during its run of <command>configure</command> is:</para>
<screen><computeroutput>checking what assembler to use...
/tools/i686-pc-linux-gnu/bin/as
checking what linker to use... /tools/i686-pc-linux-gnu/bin/ld</computeroutput></screen>
<screen><computeroutput>checking what assembler to use... /tools/i686-lfs-linux-gnu/bin/as
checking what linker to use... /tools/i686-lfs-linux-gnu/bin/ld</computeroutput></screen>
<para>This is important for the reasons mentioned above. It also demonstrates
that GCC's configure script does not search the PATH directories to find which
@ -117,34 +118,33 @@ checking what linker to use... /tools/i686-pc-linux-gnu/bin/ld</computeroutput><
<para>The next package installed is Glibc. The most important considerations
for building Glibc are the compiler, binary tools, and kernel headers. The
compiler is generally not an issue since Glibc will always use the
<command>gcc</command> found in a <envar>PATH</envar> directory. The binary
tools and kernel headers can be a bit more complicated. Therefore, take no
risks and use the available configure switches to enforce the correct
selections. After the run of <command>configure</command>, check the contents
of the <filename>config.make</filename> file in the <filename
compiler is generally not an issue since Glibc will always use the compiler
relating to the <parameter>--host</parameter> parameter passed to its
configure script, e.g. in our case,
<command>i686-lfs-linux-gnu-gcc</command>. The binary tools and kernel
headers can be a bit more complicated. Therefore, take no risks and use the
available configure switches to enforce the correct selections. After the run
of <command>configure</command>, check the contents of the
<filename>config.make</filename> file in the <filename
class="directory">glibc-build</filename> directory for all important details.
Note the use of <parameter>CC="gcc -B/tools/bin/"</parameter> to control which
binary tools are used and the use of the <parameter>-nostdinc</parameter>
and <parameter>-isystem</parameter> flags to control the compiler's include
Note the use of <parameter>CC="i686-lfs-gnu-gcc"</parameter> to control which
binary tools are used and the use of the <parameter>-nostdinc</parameter> and
<parameter>-isystem</parameter> flags to control the compiler's include
search path. These items highlight an important aspect of the Glibc
package&mdash;it is very self-sufficient in terms of its build machinery and
generally does not rely on toolchain defaults.</para>
<para>After the Glibc installation, make some adjustments to ensure that
searching and linking take place only within the <filename
class="directory">/tools</filename> prefix. Install an adjusted
<command>ld</command>, which has a hard-wired search path limited to
<filename class="directory">/tools/lib</filename>. Then amend
<command>gcc</command>'s specs file to point to the new dynamic linker in
<filename class="directory">/tools/lib</filename>. This last step is vital
to the whole process. As mentioned above, a hard-wired path to a dynamic
linker is embedded into every Executable and Link Format (ELF)-shared
executable. This can be inspected by running:
<para>After the Glibc installation, change <command>gcc</command>'s specs file
to point to the new dynamic linker in <filename
class="directory">/tools/lib</filename>. This last step is vital in ensuring
that searching and linking take place only within the <filename
class="directory">/tools</filename> prefix. A hard-wired
path to a dynamic linker is embedded into every Executable and Link Format
(ELF)-shared executable. This can be inspected by running:
<userinput>readelf -l &lt;name of binary&gt; | grep interpreter</userinput>.
Amending gcc's specs file ensures that every program compiled from here
through the end of this chapter will use the new dynamic linker in
<filename class="directory">/tools/lib</filename>.</para>
Amending <command>gcc</command>'s specs file ensures that every program
compiled from here through the end of this chapter will use the new dynamic
linker in <filename class="directory">/tools/lib</filename>.</para>
<para>For the second pass of GCC, its sources also need to be modified
to tell GCC to use the new dynamic linker. Failure to do
@ -164,8 +164,8 @@ checking what linker to use... /tools/i686-pc-linux-gnu/bin/ld</computeroutput><
linkend="chapter-building-system"/>, the first major package to be
installed is Glibc, due to its self-sufficient nature mentioned above.
Once this Glibc is installed into <filename
class="directory">/usr</filename>, perform a quick changeover of the
toolchain defaults, then proceed in building the rest of the target
class="directory">/usr</filename>, we will perform a quick changeover of the
toolchain defaults, and then proceed in building the rest of the target
LFS system.</para>
<!-- FIXME: Removed as part of the fix for bug 1061 - we no longer build pass1