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Thanks Dan Nicholson. git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@7315 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
114 lines
4.9 KiB
XML
114 lines
4.9 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 final C libraries have been installed, it is time to adjust
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the toolchain again. The toolchain will be adjusted so that it will link any
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newly compiled program against these new libraries. This is a similar process
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used in the <quote>Adjusting</quote> phase in the beginning of <xref
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linkend="chapter-temporary-tools"/>, but with the adjustments reversed. In <xref
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linkend="chapter-temporary-tools"/>, the chain was guided from the host's
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<filename class="directory">/{,usr/}lib</filename> directories to the new
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<filename class="directory">/tools/lib</filename> directory. Now, the chain will
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be guided from that same <filename class="directory">/tools/lib</filename>
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directory to the LFS <filename class="directory">/{,usr/}lib</filename>
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directories.</para>
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<para>First, backup the <filename class="directory">/tools</filename> linker, and
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replace it with the adjusted linker we made in chapter 5. We'll also create a
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link to its counterpart in <filename class="directory">/tools/$MACHTYPE/bin</filename></para>
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<screen><userinput>mv -v /tools/bin/{ld,ld-old}
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mv -v /tools/$MACHTYPE/bin/{ld,ld-old}
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mv -v /tools/bin/{ld-new,ld}
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ln -sv /tools/bin/ld /tools/$MACHTYPE/bin/ld</userinput></screen>
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<para>Next, amend the GCC specs file so that it points to the new
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dynamic linker, and so that GCC knows where to find its start files.
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A <command>perl</command> command accomplishes this:</para>
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<screen><userinput>gcc -dumpspecs | \
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perl -p -e 's@/tools/lib/ld-linux.so.2@/lib/ld-linux.so.2@g;' \
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-e 's@\*startfile_prefix_spec:\n@$_/usr/lib/ @g;' > \
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`dirname $(gcc --print-libgcc-file-name)`/specs
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</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 -Wl,--verbose &> dummy.log
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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>Now make sure that we're setup to use the correct start files:</para>
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<screen><userinput>grep "/usr/lib/crt.* " dummy.log</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:</para>
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<screen><computeroutput>attempt to open /usr/lib/crt1.o succeeded
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attempt to open /usr/lib/crti.o succeeded
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attempt to open /usr/lib/crtn.o succeeded</computeroutput></screen>
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<para>Next make sure that we're using the correct libc:</para>
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<screen><userinput>grep "/lib/libc.so.6 " dummy.log</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:</para>
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<screen><computeroutput>attempt to open /lib/libc.so.6 succeeded</computeroutput></screen>
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<para>Lastly, make sure GCC is using the correct dynamic linker:</para>
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<screen><userinput>grep found dummy.log</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>found ld-linux.so.2 at /lib/ld-linux.so.2</computeroutput></screen>
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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 -v dummy.c a.out dummy.log</userinput></screen></caution>
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</sect1>
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