source: chapter05/gcc-pass2.xml@ 6070f51

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Last change on this file since 6070f51 was 6070f51, checked in by Pierre Labastie <pieere@…>, 3 years ago

Change <productname> tags so that they reflect the dbhtml processing
instruction

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11574 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

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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-pass2</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 gcc/config/{linux,i386/linux{,64}}.h
74do
75 cp -uv $file{,.orig}
76 sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&amp;@g' \
77 -e 's@/usr@/tools@g' $file.orig &gt; $file
78 echo '
79#undef STANDARD_STARTFILE_PREFIX_1
80#undef STANDARD_STARTFILE_PREFIX_2
81#define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
82#define STANDARD_STARTFILE_PREFIX_2 ""' &gt;&gt; $file
83 touch $file.orig
84done</userinput></screen>
85
86 <para>If building on x86_64, change the default directory name for 64-bit
87 libraries to <quote>lib</quote>:</para>
88
89<screen><userinput remap="pre">case $(uname -m) in
90 x86_64)
91 sed -e '/m64=/s/lib64/lib/' \
92 -i.orig gcc/config/i386/t-linux64
93 ;;
94esac</userinput></screen>
95
96 <para>As in the first build of GCC it requires the GMP, MPFR and MPC
97 packages. Unpack the tarballs and move them into the required directory
98 names:</para>
99
100<screen><userinput remap="pre">tar -xf ../mpfr-&mpfr-version;.tar.xz
101mv -v mpfr-&mpfr-version; mpfr
102tar -xf ../gmp-&gmp-version;.tar.xz
103mv -v gmp-&gmp-version; gmp
104tar -xf ../mpc-&mpc-version;.tar.gz
105mv -v mpc-&mpc-version; mpc</userinput></screen>
106<!--
107 <para>As in the first build of GCC, fix a problem identified upstream:</para>
108
109<screen><userinput remap="pre">sed -i 's/if \((code.*))\)/if (\1 \&amp;\&amp; \!DEBUG_INSN_P (insn))/' gcc/sched-deps.c</userinput></screen>
110-->
111 <para>Create a separate build directory again:</para>
112
113<screen><userinput remap="pre">mkdir -v build
114cd build</userinput></screen>
115
116 <para>Before starting to build GCC, remember to unset any environment
117 variables that override the default optimization flags.</para>
118
119 <para>Now prepare GCC for compilation:</para>
120
121<screen><userinput remap="configure">CC=$LFS_TGT-gcc \
122CXX=$LFS_TGT-g++ \
123AR=$LFS_TGT-ar \
124RANLIB=$LFS_TGT-ranlib \
125../configure \
126 --prefix=/tools \
127 --with-local-prefix=/tools \
128 --with-native-system-header-dir=/tools/include \
129 --enable-languages=c,c++ \
130 --disable-libstdcxx-pch \
131 --disable-multilib \
132 --disable-bootstrap \
133 --disable-libgomp</userinput></screen>
134
135 <variablelist>
136 <title>The meaning of the new configure options:</title>
137
138 <varlistentry>
139 <term><parameter>--enable-languages=c,c++</parameter></term>
140 <listitem>
141 <para>This option ensures that both the C and C++ compilers are
142 built.</para>
143 </listitem>
144 </varlistentry>
145
146 <varlistentry>
147 <term><parameter>--disable-libstdcxx-pch</parameter></term>
148 <listitem>
149 <para>Do not build the pre-compiled header (PCH) for
150 <filename class="libraryfile">libstdc++</filename>. It takes up a
151 lot of space, and we have no use for it.</para>
152 </listitem>
153 </varlistentry>
154
155 <varlistentry>
156 <term><parameter>--disable-bootstrap</parameter></term>
157 <listitem>
158 <para>For native builds of GCC, the default is to do a "bootstrap"
159 build. This does not just compile GCC, but compiles it several times.
160 It uses the programs compiled in a first round to compile itself a
161 second time, and then again a third time. The second and third
162 iterations are compared to make sure it can reproduce itself
163 flawlessly. This also implies that it was compiled correctly.
164 However, the LFS build method should provide a solid compiler
165 without the need to bootstrap each time.</para>
166 </listitem>
167 </varlistentry>
168
169 </variablelist>
170
171 <para>Compile the package:</para>
172
173<screen><userinput remap="make">make</userinput></screen>
174
175 <para>Install the package:</para>
176
177<screen><userinput remap="install">make install</userinput></screen>
178
179 <para>As a finishing touch, create a symlink. Many programs and scripts
180 run <command>cc</command> instead of <command>gcc</command>, which is
181 used to keep programs generic and therefore usable on all kinds of UNIX
182 systems where the GNU C compiler is not always installed. Running
183 <command>cc</command> leaves the system administrator free to decide
184 which C compiler to install:</para>
185
186<screen><userinput remap="install">ln -sv gcc /tools/bin/cc</userinput></screen>
187
188 <caution>
189 <para>At this point, it is imperative to stop and ensure that the basic
190 functions (compiling and linking) of the new toolchain are working as
191 expected. To perform a sanity check, run the following commands:</para>
192
193<screen><userinput>echo 'int main(){}' &gt; dummy.c
194cc dummy.c
195readelf -l a.out | grep ': /tools'</userinput></screen>
196
197 <para>If everything is working correctly, there should be no errors,
198 and the output of the last command will be of the form:</para>
199
200<screen><computeroutput>[Requesting program interpreter: /tools/lib64/ld-linux-x86-64.so.2]</computeroutput></screen>
201
202 <para>Note that the dynamic linker will be /tools/lib/ld-linux.so.2
203 for 32-bit machines.</para>
204
205 <para>If the output is not shown as above or there was no output at all,
206 then something is wrong. Investigate and retrace the steps to find out
207 where the problem is and correct it. This issue must be resolved before
208 continuing on. First, perform the sanity check again, using
209 <command>gcc</command> instead of <command>cc</command>. If this works,
210 then the <filename class="symlink">/tools/bin/cc</filename> symlink is
211 missing. Install the symlink as per above.
212 Next, ensure that the <envar>PATH</envar> is correct. This
213 can be checked by running <command>echo $PATH</command> and verifying that
214 <filename class="directory">/tools/bin</filename> is at the head of the
215 list. If the <envar>PATH</envar> is wrong it could mean that you are not
216 logged in as user <systemitem class="username">lfs</systemitem> or that
217 something went wrong back in <xref linkend="ch-tools-settingenviron"
218 role="."/></para>
219
220 <para>Once all is well, clean up the test files:</para>
221
222<screen><userinput>rm -v dummy.c a.out</userinput></screen>
223
224 </caution>
225
226 </sect2>
227
228 <sect2 role="content">
229 <title/>
230
231 <para>Details on this package are located in
232 <xref linkend="contents-gcc" role="."/></para>
233
234 </sect2>
235
236</sect1>
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