[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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[b06ca36] | 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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[673b0d8] | 4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 5 | %general-entities;
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| 6 | ]>
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[3f3931b0] | 7 |
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[673b0d8] | 8 | <sect1 id="ch-system-readjusting">
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[3f3931b0] | 9 | <?dbhtml filename="readjusting.html"?>
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| 10 |
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| 11 | <title>Re-adjusting the Toolchain</title>
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| 12 |
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| 13 | <para>Now that the final C libraries have been installed, it is time to adjust
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| 14 | the toolchain again. The toolchain will be adjusted so that it will link any
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| 15 | newly compiled program against these new libraries. This is a similar process
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| 16 | used in the <quote>Adjusting</quote> phase in the beginning of <xref
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| 17 | linkend="chapter-temporary-tools"/>, but with the adjustments reversed. In <xref
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| 18 | linkend="chapter-temporary-tools"/>, the chain was guided from the host's
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| 19 | <filename class="directory">/{,usr/}lib</filename> directories to the new
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| 20 | <filename class="directory">/tools/lib</filename> directory. Now, the chain will
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| 21 | be guided from that same <filename class="directory">/tools/lib</filename>
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| 22 | directory to the LFS <filename class="directory">/{,usr/}lib</filename>
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| 23 | directories.</para>
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| 24 |
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| 25 | <para>First, backup the <filename class="directory">/tools</filename> linker,
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| 26 | and replace it with the adjusted linker we made in chapter 5. We'll also create
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| 27 | a link to its counterpart in <filename class="directory">/tools/$(gcc
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[f19e766] | 28 | -dumpmachine)/bin</filename>:</para>
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[2914987b] | 29 |
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[1ba726f] | 30 | <screen><userinput>mv -v /tools/bin/{ld,ld-old}
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[62d3362] | 31 | mv -v /tools/$(gcc -dumpmachine)/bin/{ld,ld-old}
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[1ba726f] | 32 | mv -v /tools/bin/{ld-new,ld}
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[62d3362] | 33 | ln -sv /tools/bin/ld /tools/$(gcc -dumpmachine)/bin/ld</userinput></screen>
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[2914987b] | 34 |
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[04a77025] | 35 | <para>Next, amend the GCC specs file so that it points to the new
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[78367651] | 36 | dynamic linker, and so that GCC knows where to find the correct headers
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| 37 | and Glibc start files. A <command>sed</command> command accomplishes
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[f19e766] | 38 | this:</para>
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[54592a1] | 39 |
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| 40 | <important>
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| 41 | <para>If working on a platform where the name of the dynamic linker is
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| 42 | something other than <filename class="libraryfile">ld-linux.so.2</filename>,
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| 43 | substitute <quote>ld-linux.so.2</quote> with the name of the platform's
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| 44 | dynamic linker in the following commands. Refer to <xref
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| 45 | linkend="ch-tools-toolchaintechnotes" role=","/> if necessary.</para>
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| 46 | </important>
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[673b0d8] | 47 |
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[e9a652b] | 48 | <screen><userinput>gcc -dumpspecs | sed \
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| 49 | -e 's@/tools/lib/ld-linux.so.2@/lib/ld-linux.so.2@g' \
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| 50 | -e '/\*startfile_prefix_spec:/{n;s@.*@/usr/lib/ @}' \
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| 51 | -e '/\*cpp:/{n;s@$@ -isystem /usr/include@}' > \
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[3f3931b0] | 52 | `dirname $(gcc --print-libgcc-file-name)`/specs</userinput></screen>
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| 53 |
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| 54 | <para>It is a good idea to visually inspect the specs file to verify the
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| 55 | intended change was actually made.</para>
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| 56 |
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[09f1daf] | 57 | <para>It is imperative at this point to ensure that the basic
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| 58 | functions (compiling and linking) of the adjusted toolchain are working
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| 59 | as expected. To do this, perform the following sanity checks:</para>
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[673b0d8] | 60 |
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[006ed03] | 61 | <screen os="a"><userinput>echo 'main(){}' > dummy.c
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[e9a652b] | 62 | cc dummy.c -v -Wl,--verbose &> dummy.log
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[673b0d8] | 63 | readelf -l a.out | grep ': /lib'</userinput></screen>
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| 64 |
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[09f1daf] | 65 | <para os="b">If everything is working correctly, there should be no errors,
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| 66 | and the output of the last command will be (allowing for
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| 67 | platform-specific differences in dynamic linker name):</para>
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[673b0d8] | 68 |
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[09f1daf] | 69 | <screen os="c"><computeroutput>[Requesting program interpreter: /lib/ld-linux.so.2]</computeroutput></screen>
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[673b0d8] | 70 |
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[09f1daf] | 71 | <para>Note that <filename class="directory">/lib</filename> is now
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| 72 | the prefix of our dynamic linker.</para>
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[673b0d8] | 73 |
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[09f1daf] | 74 | <para os="d">Now make sure that we're setup to use the correct startfiles:</para>
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[2914987b] | 75 |
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[570f6bb] | 76 | <screen os="e"><userinput>grep -o '/usr/lib.*/crt[1in].*succeeded' dummy.log</userinput></screen>
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[2914987b] | 77 |
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[09f1daf] | 78 | <para os="f">If everything is working correctly, there should be no errors,
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[3f3931b0] | 79 | and the output of the last command will be:</para>
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[2914987b] | 80 |
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[09f1daf] | 81 | <screen><computeroutput>/usr/lib/crt1.o succeeded
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| 82 | /usr/lib/crti.o succeeded
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| 83 | /usr/lib/crtn.o succeeded</computeroutput></screen>
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[2914987b] | 84 |
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[e9a652b] | 85 | <para os="g">Verify that the compiler is searching for the correct header
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| 86 | files:</para>
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[2914987b] | 87 |
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[006ed03] | 88 | <screen><userinput>grep -B1 '^ /usr/include' dummy.log</userinput></screen>
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[2914987b] | 89 |
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[e9a652b] | 90 | <para os="h">This command should return successfully with the following output:</para>
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| 91 |
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| 92 | <screen><computeroutput>#include <...> search starts here:
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| 93 | /usr/include</computeroutput></screen>
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| 94 |
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| 95 | <para os="i">Next, verify that the new linker is being used with the correct search paths:</para>
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| 96 |
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[006ed03] | 97 | <screen os="j"><userinput>grep 'SEARCH.*/usr/lib' dummy.log |sed 's|; |\n|g'</userinput></screen>
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[e9a652b] | 98 |
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| 99 | <para os="k">If everything is working correctly, there should be no errors,
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[09f1daf] | 100 | and the output of the last command will be:</para>
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| 101 |
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| 102 | <screen><computeroutput>SEARCH_DIR("/tools/i686-pc-linux-gnu/lib")
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| 103 | SEARCH_DIR("/usr/lib")
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| 104 | SEARCH_DIR("/lib");</computeroutput></screen>
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| 105 |
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[e9a652b] | 106 | <para os="l">Next make sure that we're using the correct libc:</para>
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[09f1daf] | 107 |
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[006ed03] | 108 | <screen os="m"><userinput>grep "/lib/libc.so.6 " dummy.log</userinput></screen>
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[09f1daf] | 109 |
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[e9a652b] | 110 | <para os="n">If everything is working correctly, there should be no errors,
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[09f1daf] | 111 | and the output of the last command will be:</para>
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[2914987b] | 112 |
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[e9a652b] | 113 | <screen os="o"><computeroutput>attempt to open /lib/libc.so.6 succeeded</computeroutput></screen>
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[2914987b] | 114 |
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[e9a652b] | 115 | <para os="p">Lastly, make sure GCC is using the correct dynamic linker:</para>
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[2914987b] | 116 |
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[006ed03] | 117 | <screen os="q"><userinput>grep found dummy.log</userinput></screen>
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[2914987b] | 118 |
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[e9a652b] | 119 | <para os="r">If everything is working correctly, there should be no errors,
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[09f1daf] | 120 | and the output of the last command will be (allowing for
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| 121 | platform-specific differences in dynamic linker name):</para>
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[2914987b] | 122 |
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[e9a652b] | 123 | <screen os="s"><computeroutput>found ld-linux.so.2 at /lib/ld-linux.so.2</computeroutput></screen>
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[2914987b] | 124 |
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[e9a652b] | 125 | <para os="t">If the output does not appear as shown above or is not received
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[09f1daf] | 126 | at all, then something is seriously wrong. Investigate and retrace the
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| 127 | steps to find out where the problem is and correct it. The most likely
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| 128 | reason is that something went wrong with the specs file adjustment. Any
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| 129 | issues will need to be resolved before continuing on with the process.</para>
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[673b0d8] | 130 |
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[e9a652b] | 131 | <para os="u">Once everything is working correctly, clean up the test files:</para>
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[81fd230] | 132 |
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[006ed03] | 133 | <screen os="v"><userinput>rm -v dummy.c a.out dummy.log</userinput></screen>
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[673b0d8] | 134 |
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| 135 | </sect1>
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