mirror of https://github.com/tLDP/LDP
80 lines
3.6 KiB
XML
80 lines
3.6 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/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-tools-adjusting">
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<?dbhtml filename="adjusting.html"?>
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<title>Adjusting the Toolchain</title>
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<para>Now that the temporary C libraries have been installed, all
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tools compiled in the rest of this chapter should be linked against
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these libraries. In order to accomplish this, the cross-compiler's
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specs file needs to be adjusted to point to the new dynamic linker
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in <filename class="directory">/tools</filename>.</para>
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<para>This is done by dumping the compiler's <quote>specs</quote> file to a
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location where it will look for it by default.
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A simple <command>sed</command> substitution then alters the
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dynamic linker that GCC will use. The principle here is to find all references
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to the dynamic linker file in <filename class="directory">/lib</filename>
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or possibly <filename class="directory">/lib64</filename> if the host system
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is 64-bit capable, and adjust them to point to the new location in
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<filename class="directory">/tools</filename>.</para>
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<para>For the sake of accuracy, it is recommended to use a copy-and-paste
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method when issuing the following command. Be sure to visually inspect the
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specs file to verify that it has properly adjusted all references to the
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dynamic linker location. Refer to <xref
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linkend="ch-tools-toolchaintechnotes" role=","/> for the default name
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of the dynamic linker, if necessary.</para>
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<!-- Ampersands are needed to allow copy and paste -->
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<screen><userinput>SPECS=`dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/specs
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$LFS_TGT-gcc -dumpspecs | sed \
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-e 's@/lib\(64\)\?/ld@/tools&@g' \
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-e "/^\*cpp:$/{n;s,$, -isystem /tools/include,}" > $SPECS
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echo "New specs file is: $SPECS"
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unset SPECS</userinput></screen>
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<caution>
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<para>At this point, it is imperative to stop and ensure that the basic
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functions (compiling and linking) of the new toolchain are working as
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expected. To perform a sanity check, run the following commands:</para>
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<screen><userinput>echo 'int main(){}' > dummy.c
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$LFS_TGT-gcc -B/tools/lib dummy.c
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readelf -l a.out | grep ': /tools'</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 of the form:</para>
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<screen><computeroutput>[Requesting program interpreter: /tools/lib/ld-linux.so.2]</computeroutput></screen>
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<para>Note that <filename class="directory">/tools/lib</filename>, or
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<filename class="directory">/tools/lib64</filename> for 64-bit machines
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appears as the prefix of the dynamic linker.</para>
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<para>If the output is not shown as above or there was no output at all,
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then something is wrong. Investigate and retrace the steps to find out
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where the problem is and correct it. This issue must be resolved before
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continuing on. Something may have gone wrong with the
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specs file amendment above. In this case, redo the specs file amendment,
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being careful to copy-and-paste the commands.</para>
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<para>Once all is well, clean up the test files:</para>
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<screen><userinput>rm -v dummy.c a.out</userinput></screen>
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</caution>
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<note><para>Building Binutils in the next section will serve as an additional check that
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the toolchain has been built properly. If Binutils fails to build, it is an
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indication that something has gone wrong with the previous Binutils, GCC, or Glibc
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installations.</para></note>
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</sect1>
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