1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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3 | <!ENTITY % general-entities SYSTEM "../general.ent">
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4 | %general-entities;
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5 | ]>
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6 | <sect1 id="ch-tools-adjusting">
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7 | <title>Adjusting the toolchain</title>
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8 | <?dbhtml filename="adjusting.html"?>
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9 |
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10 | <para>Now that the temporary C libraries have been installed, all
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11 | the tools compiled in the rest of this chapter should be linked against these
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12 | libraries. In order to accomplish this the linker, and the compiler's
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13 | specs file, need to be adjsted.</para>
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14 |
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15 | <para> Some people would say that there is <emphasis><quote>black magic juju
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16 | below this line</quote></emphasis>, but it is really very simple.</para>
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17 |
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18 | <para>First the adjusted linker is installed (adjusted at the end of the first pass
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19 | of Binutils), by running the following command from within
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20 | the <filename class="directory">binutils-build</filename> directory:</para>
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21 |
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22 | <screen><userinput>make -C ld install</userinput></screen>
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23 |
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24 | <para>From this point onwards everything will link <emphasis>only</emphasis>
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25 | against the libraries in <filename class="directory">/tools/lib</filename>.</para>
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26 |
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27 | <note><para>If you missed the earlier warning to retain the Binutils
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28 | source and build directories from the first pass, dont worry - all is not lost.
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29 | Just ignore the above command. This results in a small chance of the subsequent
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30 | testing programs linking against libraries on the host. This is not ideal, but
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31 | it's not a major problem. The situation is corrected when the second pass of
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32 | Binutils is installed later on.</para></note>
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33 |
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34 | <para>Now that the adjusted linker is installed, the Binutils build and source
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35 | directories should be <emphasis>removed</emphasis>.</para>
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36 |
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37 | <para>The next task is to amend our GCC specs file so that it points
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38 | to the new dynamic linker. A simple sed script will accomplish this:</para>
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39 |
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40 | <!-- Ampersands are needed to allow cut and paste -->
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41 |
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42 | <screen><userinput>SPECFILE=`gcc --print-file specs` &&
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43 | sed 's@ /lib/ld-linux.so.2@ /tools/lib/ld-linux.so.2@g' \
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44 | $SPECFILE > tempspecfile &&
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45 | mv -f tempspecfile $SPECFILE &&
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46 | unset SPECFILE</userinput></screen>
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47 |
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48 | <para>It is recommended that the above command be cut-and-pasted in order to ensure correctness - Alternatively the specs file can be edited by hand. This is done simply by replacing every occurrence of <quote>/lib/ld-linux.so.2</quote> with <quote>/tools/lib/ld-linux.so.2</quote>.</para>
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49 |
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50 | <para> Be sure to visually inspect the specs file in order to verify the intended changes have been made.</para>
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51 |
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52 | <important><para>If you are working on a platform where the name of the dynamic
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53 | linker is something other than <filename>ld-linux.so.2</filename>, you
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54 | <emphasis>must</emphasis> replace <filename>ld-linux.so.2</filename> with the
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55 | name of your platform's dynamic linker in the above commands. Refer back to
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56 | <xref linkend="ch-tools-toolchaintechnotes"/> if necessary.</para></important>
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57 |
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58 | <para>Lastly, there is a possibility that some include files from the host
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59 | system have found their way into GCC's private include dir. This can happen
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60 | as a result of of GCC's <quote>fixincludes</quote> process which runs as part
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61 | of the GCC build. We'll explain more about this further on in this chapter.
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62 | Run the following commands to eliminate this possibility:</para>
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63 |
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64 | <screen><userinput>rm -f /tools/lib/gcc/*/*/include/{pthread.h,bits/sigthread.h}</userinput></screen>
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65 |
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66 |
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67 | <caution><para>It is imperative at this point to stop and ensure that the basic
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68 | functions (compiling and linking) of the new toolchain are working as expected.
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69 | To perform a simple sanity check run the following commands:</para>
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70 |
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71 | <screen><userinput>echo 'main(){}' > dummy.c
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72 | cc dummy.c
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73 | readelf -l a.out | grep ': /tools'</userinput></screen>
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74 |
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75 | <para>If everything is working correctly, there should be no errors, and the
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76 | output of the last command will be of the form:</para>
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77 |
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78 | <blockquote><screen><computeroutput>[Requesting program interpreter: /tools/lib/ld-linux.so.2]</computeroutput></screen></blockquote>
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79 |
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80 | <para>Note especially that <filename class="directory">/tools/lib</filename>
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81 | appears as the prefix of our dynamic linker.</para>
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82 |
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83 | <para>If the output is not
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84 | as shown above, or there was no output at all, then something is seriously
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85 | wrong. You will need to investigate and retrace your steps to find out where the
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86 | problem is and correct it. There is no point in continuing until this is done.
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87 | First, perform the sanity check again, using <command>gcc</command> instead of
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88 | <command>cc</command>. If this works then the
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89 | <filename class="symlink">/tools/bin/cc</filename> symlink is missing. Revisit
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90 | <xref linkend="ch-tools-gcc-pass1"/> and install the symlink. Second, ensure your PATH
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91 | is correct. You can check this by running <userinput>echo $PATH</userinput> and
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92 | verifying that <filename class="directory">/tools/bin</filename> is at the head
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93 | of the list. If the PATH is wrong it could mean you're not logged in as user
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94 | <emphasis>lfs</emphasis> or something went wrong back in
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95 | <xref linkend="ch-tools-settingenviron"/>. Third, something may have gone wrong with
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96 | the specs file amendment above. In this case redo the specs file amendment
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97 | being careful to cut-and-paste the commands.</para>
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98 |
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99 | <para>Once you are satisfied that all is well, clean up the test files:</para>
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100 |
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101 | <screen><userinput>rm dummy.c a.out</userinput></screen>
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102 | </caution>
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103 |
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104 |
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105 | </sect1>
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