source: chapter05/gcc-pass2.xml@ dbc347c5

7.9-systemd 7.9-systemd-rc1 7.9-systemd-rc2 systemd
Last change on this file since dbc347c5 was dbc347c5, checked in by Douglas R. Reno <renodr@…>, 7 years ago

Update to util-linux-2.27
Update to linux-4.2
Update to iproute2-4.2.0
Refresh SBU values and build sizes
Remove unnecessary sed in e2fsprogs
Provide ncurses non-wide-character libraries for version 5
Add additional discussion about copying systems
Fix a warning in the GCC compiler tests
Several typo fixes and additional clarification.

git-svn-id: http://svn.linuxfromscratch.org/LFS/branches/systemd@10956 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

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File size: 8.9 KB
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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-tools-gcc-pass2" role="wrap">
9 <?dbhtml filename="gcc-pass2.html"?>
10
11 <sect1info condition="script">
12 <productname>gcc</productname>
13 <productnumber>&gcc-version;</productnumber>
14 <address>&gcc-url;</address>
15 </sect1info>
16
17 <title>GCC-&gcc-version; - Pass 2</title>
18
19 <indexterm zone="ch-tools-gcc-pass2">
20 <primary sortas="a-GCC">GCC</primary>
21 <secondary>tools, pass 2</secondary>
22 </indexterm>
23
24 <sect2 role="package">
25 <title/>
26
27 <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
28 href="../chapter06/gcc.xml"
29 xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
30
31 <segmentedlist>
32 <segtitle>&buildtime;</segtitle>
33 <segtitle>&diskspace;</segtitle>
34
35 <seglistitem>
36 <seg>&gcc-ch5p2-sbu;</seg>
37 <seg>&gcc-ch5p2-du;</seg>
38 </seglistitem>
39 </segmentedlist>
40
41 </sect2>
42
43 <sect2 role="installation">
44 <title>Installation of GCC</title>
45
46 <para>Our first build of GCC has installed a couple of internal system
47 headers. Normally one of them, <filename>limits.h</filename>, will in turn
48 include the corresponding system <filename>limits.h</filename> header, in
49 this case, <filename>/tools/include/limits.h</filename>. However, at the
50 time of the first build of gcc <filename>/tools/include/limits.h</filename>
51 did not exist, so the internal header that GCC installed is a partial,
52 self-contained file and does not include the extended features of the
53 system header. This was adequate for building the temporary libc, but this
54 build of GCC now requires the full internal header. Create a full version
55 of the internal header using a command that is identical to what the GCC
56 build system does in normal circumstances:</para>
57
58<screen><userinput remap="pre">cat gcc/limitx.h gcc/glimits.h gcc/limity.h &gt; \
59 `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include-fixed/limits.h</userinput></screen>
60<!--
61 <para>For x86 machines, the limited number of registers is a bottleneck
62 for the system. Free one up by not using a frame pointer that is not
63 needed:</para>
64
65<screen><userinput remap="pre">case `uname -m` in
66 i?86) sed -i 's/^T_CFLAGS =$/&amp; -fomit-frame-pointer/' gcc/Makefile.in ;;
67esac</userinput></screen>
68-->
69 <para>Once again, change the location of GCC's default dynamic linker to
70 use the one installed in <filename
71 class="directory">/tools</filename>.</para>
72
73<screen><userinput remap="pre">for file in \
74 $(find gcc/config -name linux64.h -o -name linux.h -o -name sysv4.h)
75do
76 cp -uv $file{,.orig}
77 sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&amp;@g' \
78 -e 's@/usr@/tools@g' $file.orig &gt; $file
79 echo '
80#undef STANDARD_STARTFILE_PREFIX_1
81#undef STANDARD_STARTFILE_PREFIX_2
82#define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
83#define STANDARD_STARTFILE_PREFIX_2 ""' &gt;&gt; $file
84 touch $file.orig
85done</userinput></screen>
86
87 <para>As in the first build of GCC it requires the GMP, MPFR and MPC
88 packages. Unpack the tarballs and move them into the required directory
89 names:</para>
90
91<screen><userinput remap="pre">tar -xf ../mpfr-&mpfr-version;.tar.xz
92mv -v mpfr-&mpfr-version; mpfr
93tar -xf ../gmp-&gmp-version;.tar.xz
94mv -v gmp-&gmp-extracted-version; gmp
95tar -xf ../mpc-&mpc-version;.tar.gz
96mv -v mpc-&mpc-version; mpc</userinput></screen>
97<!--
98 <para>As in the first build of GCC, fix a problem identified upstream:</para>
99
100<screen><userinput remap="pre">sed -i 's/if \((code.*))\)/if (\1 \&amp;\&amp; \!DEBUG_INSN_P (insn))/' gcc/sched-deps.c</userinput></screen>
101-->
102 <para>Create a separate build directory again:</para>
103
104<screen><userinput remap="pre">mkdir -v ../gcc-build
105cd ../gcc-build</userinput></screen>
106
107 <para>Before starting to build GCC, remember to unset any environment
108 variables that override the default optimization flags.</para>
109
110 <para>Now prepare GCC for compilation:</para>
111
112<screen><userinput remap="configure">CC=$LFS_TGT-gcc \
113CXX=$LFS_TGT-g++ \
114AR=$LFS_TGT-ar \
115RANLIB=$LFS_TGT-ranlib \
116../gcc-&gcc-version;/configure \
117 --prefix=/tools \
118 --with-local-prefix=/tools \
119 --with-native-system-header-dir=/tools/include \
120 --enable-languages=c,c++ \
121 --disable-libstdcxx-pch \
122 --disable-multilib \
123 --disable-bootstrap \
124 --disable-libgomp</userinput></screen>
125
126 <variablelist>
127 <title>The meaning of the new configure options:</title>
128
129 <varlistentry>
130 <term><parameter>--enable-languages=c,c++</parameter></term>
131 <listitem>
132 <para>This option ensures that both the C and C++ compilers are
133 built.</para>
134 </listitem>
135 </varlistentry>
136
137 <varlistentry>
138 <term><parameter>--disable-libstdcxx-pch</parameter></term>
139 <listitem>
140 <para>Do not build the pre-compiled header (PCH) for
141 <filename class="libraryfile">libstdc++</filename>. It takes up a
142 lot of space, and we have no use for it.</para>
143 </listitem>
144 </varlistentry>
145
146 <varlistentry>
147 <term><parameter>--disable-bootstrap</parameter></term>
148 <listitem>
149 <para>For native builds of GCC, the default is to do a "bootstrap"
150 build. This does not just compile GCC, but compiles it several times.
151 It uses the programs compiled in a first round to compile itself a
152 second time, and then again a third time. The second and third
153 iterations are compared to make sure it can reproduce itself
154 flawlessly. This also implies that it was compiled correctly.
155 However, the LFS build method should provide a solid compiler
156 without the need to bootstrap each time.</para>
157 </listitem>
158 </varlistentry>
159
160 </variablelist>
161
162 <para>Compile the package:</para>
163
164<screen><userinput remap="make">make</userinput></screen>
165
166 <para>Install the package:</para>
167
168<screen><userinput remap="install">make install</userinput></screen>
169
170 <para>As a finishing touch, create a symlink. Many programs and scripts
171 run <command>cc</command> instead of <command>gcc</command>, which is
172 used to keep programs generic and therefore usable on all kinds of UNIX
173 systems where the GNU C compiler is not always installed. Running
174 <command>cc</command> leaves the system administrator free to decide
175 which C compiler to install:</para>
176
177<screen><userinput remap="install">ln -sv gcc /tools/bin/cc</userinput></screen>
178
179 <caution>
180 <para>At this point, it is imperative to stop and ensure that the basic
181 functions (compiling and linking) of the new toolchain are working as
182 expected. To perform a sanity check, run the following commands:</para>
183
184<screen><userinput>echo 'int main(){}' &gt; dummy.c
185cc dummy.c
186readelf -l a.out | grep ': /tools'</userinput></screen>
187
188 <para>If everything is working correctly, there should be no errors,
189 and the output of the last command will be of the form:</para>
190
191<screen><computeroutput>[Requesting program interpreter: /tools/lib/ld-linux.so.2]</computeroutput></screen>
192
193 <para>Note that <filename class="directory">/tools/lib</filename>, or
194 <filename class="directory">/tools/lib64</filename> for 64-bit machines
195 appears as the prefix of the dynamic linker.</para>
196
197 <para>If the output is not shown as above or there was no output at all,
198 then something is wrong. Investigate and retrace the steps to find out
199 where the problem is and correct it. This issue must be resolved before
200 continuing on. First, perform the sanity check again, using
201 <command>gcc</command> instead of <command>cc</command>. If this works,
202 then the <filename class="symlink">/tools/bin/cc</filename> symlink is
203 missing. Install the symlink as per above.
204 Next, ensure that the <envar>PATH</envar> is correct. This
205 can be checked by running <command>echo $PATH</command> and verifying that
206 <filename class="directory">/tools/bin</filename> is at the head of the
207 list. If the <envar>PATH</envar> is wrong it could mean that you are not
208 logged in as user <systemitem class="username">lfs</systemitem> or that
209 something went wrong back in <xref linkend="ch-tools-settingenviron"
210 role="."/></para>
211
212 <para>Once all is well, clean up the test files:</para>
213
214<screen><userinput>rm -v dummy.c a.out</userinput></screen>
215
216 </caution>
217
218 </sect2>
219
220 <sect2 role="content">
221 <title/>
222
223 <para>Details on this package are located in
224 <xref linkend="contents-gcc" role="."/></para>
225
226 </sect2>
227
228</sect1>
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