source: BOOK/final-system/common/adjusting.xml @ cc14b18

systemd
Last change on this file since cc14b18 was cc14b18, checked in by William Harrington <kb0iic@…>, 5 years ago

Add int to main since GCC 5 returns defaults to int [-Wimplicit-int]. Suppress the warning.

  • Property mode set to 100644
File size: 2.4 KB
Line 
1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4  <!ENTITY % general-entities SYSTEM "../../general.ent">
5  %general-entities;
6]>
7
8<sect1 id="ch-system-adjusting">
9  <?dbhtml filename="adjusting.html"?>
10
11  <title>Adjusting the Toolchain</title>
12
13  <para os="a">Now we adjust GCC's specs so that they point to the new
14  dynamic linker. A <command>perl</command> command accomplishes this:</para>
15
16<screen os="c"><userinput>gcc -dumpspecs | \
17perl -p -e 's@/tools/lib/ld@/lib/ld@g;' \
18     -e 's@\*startfile_prefix_spec:\n@$_/usr/lib/ @g;' &gt; \
19     $(dirname $(gcc --print-libgcc-file-name))/specs</userinput></screen>
20
21  <para os="d">The <command>perl</command> command above makes 2
22  modifications to GCC's specs: it removes <quote>/tools</quote> from the
23  pathname to the dynamic linker, and adds <quote>/usr/lib/</quote> to the
24  startfile_prefix_spec. It is a good idea to visually inspect the
25  <filename>specs</filename> file, and compare with the output of
26  <command>gcc -dumpspecs</command>, to verify that
27  the intended changes were actually made.</para>
28
29  <caution>
30
31    <para os="f">It is imperative at this point to stop and ensure that
32    the basic functions (compiling and linking) of the adjusted toolchain
33    are working as expected. To do this, perform a sanity
34    check:</para>
35
36<screen os="g"><userinput>echo 'int main(){}' &gt; dummy.c
37gcc dummy.c
38readelf -l a.out | grep ': /lib'</userinput></screen>
39
40    <para os="h">If everything is working correctly, there should be no errors,
41    and the output of the last command will be:</para>
42
43<screen os="i"><computeroutput>[Requesting program interpreter: /lib/ld-linux.so.2]</computeroutput></screen>
44
45    <para os="j">Note that <filename class="directory">/lib</filename> is now
46    the prefix of our dynamic linker.</para>
47
48    <para os="k">If the output does not appear as shown above or is not received
49    at all, then something is seriously wrong. Investigate and retrace the
50    steps to find out where the problem is and correct it. The most likely
51    reason is that something went wrong with the specs file amendment
52    above. Any issues will need to be resolved before continuing on with
53    the process.</para>
54
55    <para os="l">Once everything is working correctly, clean up the test
56    files:</para>
57
58<screen os="m"><userinput>rm -v dummy.c a.out</userinput></screen>
59
60  </caution>
61
62</sect1>
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