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git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@4648 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
106 lines
4.8 KiB
XML
106 lines
4.8 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../general.ent">
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%general-entities;
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]>
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<sect1 id="ch-system-readjusting">
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<title>Re-adjusting the Toolchain</title>
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<?dbhtml filename="readjusting.html"?>
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<para>Now that the new and final C libraries have been installed, it
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is time to adjust the toolchain again. The toolchain will be adjusted
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so that it will link any newly compiled program against these new
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libraries. This is the same process used in the
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<quote>Adjusting</quote> phase in the beginning of <xref
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linkend="chapter-temporary-tools"/>, even though it looks to be
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reversed. In <xref linkend="chapter-temporary-tools"/>, the chain was
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guided from the host's <filename
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class="directory">/{,usr/}lib</filename> directories to the new
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<filename class="directory">/tools/lib</filename> directory. Now, the
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chain will be guided from that same <filename
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class="directory">/tools/lib</filename> directory to the LFS
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<filename class="directory">/{,usr/}lib</filename> directories.</para>
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<para>Start by adjusting the linker. The source and build directories
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from the second pass over Binutils were retained for this purpose.
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Install the adjusted linker by running the following command from
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within the <filename class="directory">binutils-build</filename>
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directory:</para>
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<screen><userinput>make -C ld INSTALL=/tools/bin/install install</userinput></screen>
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<note><para>If the earlier warning to retain the Binutils source and
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build directories from the second pass in <xref
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linkend="chapter-temporary-tools"/> was missed, or if they were
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accidentally deleted or are inaccessible, ignore the above command.
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The result will be that the next package, Binutils, will link against
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the C libraries in <filename class="directory">/tools</filename>
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rather than in <filename class="directory">/{,usr/}lib</filename>.
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This is not ideal, however, testing has shown that the resulting
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Binutils program binaries should be identical.</para></note>
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<para>From now on, every compiled program will link only against the
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libraries in <filename class="directory">/usr/lib</filename> and
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<filename class="directory">/lib</filename>. The extra
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<parameter>INSTALL=/tools/bin/install</parameter> option is needed
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because the <filename>Makefile</filename> file created during the
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second pass still contains the reference to
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<command>/usr/bin/install</command>, which has not been installed yet.
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Some host distributions contain a <filename
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class="symlink">ginstall</filename> symbolic link which takes
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precedence in the <filename>Makefile</filename> file and can cause a
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problem. The above command takes care of this issue.</para>
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<para>Remove the Binutils source and build directories now.</para>
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<para>Next, amend the GCC specs file so that it points to the new
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dynamic linker. A perl command accomplishes this:</para>
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<screen><userinput>perl -pi -e 's@ /tools/lib/ld-linux.so.2@ /lib/ld-linux.so.2@g;' \
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-e 's@\*startfile_prefix_spec:\n@$_/usr/lib/ @g;' \
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`gcc --print-file specs`</userinput></screen>
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<para>It is a good idea to visually inspect the specs file to verify the intended
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change was actually made.</para>
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<important><para>If working on a platform where the name of the
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dynamic linker is something other than
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<filename class="libraryfile">ld-linux.so.2</filename>, substitute
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<quote>ld-linux.so.2</quote> with the name of the platform's
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dynamic linker in the above commands. Refer back to <xref
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linkend="ch-tools-toolchaintechnotes" role=","/> if
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necessary.</para></important>
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<caution><para>It is imperative at this point to stop and ensure that
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the basic functions (compiling and linking) of the adjusted toolchain
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are working as expected. To do this, perform a sanity
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check:</para>
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<screen><userinput>echo 'main(){}' > dummy.c
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cc dummy.c
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readelf -l a.out | grep ': /lib'</userinput></screen>
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<para>If everything is working correctly, there should be no errors,
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and the output of the last command will be (allowing for
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platform-specific differences in dynamic linker name):</para>
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<screen><computeroutput>[Requesting program interpreter: /lib/ld-linux.so.2]</computeroutput></screen>
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<para>Note that <filename class="directory">/lib</filename> is now
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the prefix of our dynamic linker.</para>
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<para>If the output does not appear as shown above or is not received
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at all, then something is seriously wrong. Investigate and retrace the
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steps to find out where the problem is and correct it. The most likely
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reason is that something went wrong with the specs file amendment
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above. Any issues will need to be resolved before continuing on with
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the process.</para>
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<para>Once everything is working correctly, clean up the test
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files:</para>
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<screen><userinput>rm dummy.c a.out</userinput></screen></caution>
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</sect1>
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