| 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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| 4 | <!ENTITY % general-entities SYSTEM "../../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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| 7 |
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| 8 | <sect1 id="ch-system-adjusting">
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| 9 | <?dbhtml filename="adjusting.html"?>
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| 10 |
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| 11 | <title>Adjusting the Toolchain</title>
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| 12 |
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| 13 | <para os="a">Now we adjust GCC's specs so that they point to the new
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| 14 | dynamic linker. A <command>perl</command> command accomplishes this:</para>
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| 15 |
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| 16 | <screen os="c"><userinput>gcc -dumpspecs | \
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| 17 | perl -p -e 's@/tools/lib/ld@/lib/ld@g;' \
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| 18 | -e 's@\*startfile_prefix_spec:\n@$_/usr/lib/ @g;' > \
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| 19 | $(dirname $(gcc --print-libgcc-file-name))/specs</userinput></screen>
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| 20 |
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| 21 | <para os="d">The <command>perl</command> command above makes 2
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| 22 | modifications to GCC's specs: it removes <quote>/tools</quote> from the
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| 23 | pathname to the dynamic linker, and adds <quote>/usr/lib/</quote> to the
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| 24 | startfile_prefix_spec. It is a good idea to visually inspect the
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| 25 | <filename>specs</filename> file, and compare with the output of
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| 26 | <command>gcc -dumpspecs</command>, to verify that
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| 27 | the intended changes were actually made.</para>
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| 28 |
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| 29 | <para os="e">Note that <filename class="directory">/lib</filename> is now
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| 30 | the prefix of our dynamic linker.</para>
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| 31 |
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| 32 | <caution>
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| 33 |
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| 34 | <para os="f">It is imperative at this point to stop and ensure that
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| 35 | the basic functions (compiling and linking) of the adjusted toolchain
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| 36 | are working as expected. To do this, perform a sanity
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| 37 | check:</para>
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| 38 |
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| 39 | <screen os="g"><userinput>echo 'main(){}' > dummy.c
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| 40 | gcc dummy.c
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| 41 | readelf -l a.out | grep ': /lib'</userinput></screen>
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| 42 |
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| 43 | <para os="h">If everything is working correctly, there should be no errors,
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| 44 | and the output of the last command will be:</para>
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| 45 |
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| 46 | <screen os="i"><computeroutput>[Requesting program interpreter: /lib/ld-linux.so.2]</computeroutput></screen>
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| 47 |
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| 48 | <para os="j">Note that <filename class="directory">/lib</filename> is now
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| 49 | the prefix of our dynamic linker.</para>
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| 50 |
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| 51 | <para os="k">If the output does not appear as shown above or is not received
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| 52 | at all, then something is seriously wrong. Investigate and retrace the
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| 53 | steps to find out where the problem is and correct it. The most likely
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| 54 | reason is that something went wrong with the specs file amendment
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| 55 | above. Any issues will need to be resolved before continuing on with
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| 56 | the process.</para>
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| 57 |
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| 58 | <para os="l">Once everything is working correctly, clean up the test
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| 59 | files:</para>
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| 60 |
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| 61 | <screen os="m"><userinput>rm -v dummy.c a.out</userinput></screen>
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| 62 |
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| 63 | </caution>
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| 64 |
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| 65 | </sect1>
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