source: chapter06/gcc-pass2.xml@ 964103c

xry111/clfs-ng
Last change on this file since 964103c was 964103c, checked in by Xi Ruoyao <xry111@…>, 9 months ago

Merge branch 'trunk' into xry111/clfs-ng

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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" xreflabel="gcc-pass2">
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="../chapter08/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-tmpp2-sbu;</seg>
37 <seg>&gcc-tmpp2-du;</seg>
38 </seglistitem>
39 </segmentedlist>
40
41 </sect2>
42
43 <sect2 role="installation">
44 <title>Installation of GCC</title>
45
46 <para>As in the first build of GCC, the GMP, MPFR, and MPC packages are
47 required. Unpack the tarballs and move them into the required directory
48 names:</para>
49
50<screen><userinput remap="pre">tar -xf ../mpfr-&mpfr-version;.tar.xz
51mv -v mpfr-&mpfr-version; mpfr
52tar -xf ../gmp-&gmp-version;.tar.xz
53mv -v gmp-&gmp-version; gmp
54tar -xf ../mpc-&mpc-version;.tar.gz
55mv -v mpc-&mpc-version; mpc</userinput></screen>
56
57 <para>For x86_64 target, set the default directory name for
58 64-bit libraries to <quote>lib</quote>. The command is unnecessary,
59 but harmless for 32-bit x86. If you are building for another target,
60 you may need to adjust the command for your target.</para>
61
62<screen><userinput remap="pre">sed -e '/m64=/s/lib64/lib/' \
63 -i.orig gcc/config/i386/t-linux64</userinput></screen>
64
65 <!-- https://gcc.gnu.org/PR100017 -->
66 <para>Fix an issue causing failure cross-compiling libstdc++:</para>
67
68<screen><userinput remap="pre">sed 's/gnu++17/&amp; -nostdinc++/' \
69 -i libstdc++-v3/src/c++17/Makefile.in</userinput></screen>
70
71 <para>Override the building rule of libgcc and libstdc++ headers, to
72 allow building these libraries with POSIX threads support:</para>
73
74<screen><userinput remap="pre">sed '/thread_header =/s/@.*@/gthr-posix.h/' \
75 -i libgcc/Makefile.in libstdc++-v3/include/Makefile.in</userinput></screen>
76
77 <para>Create a separate build directory again:</para>
78
79<screen><userinput remap="pre">mkdir -v build
80cd build</userinput></screen>
81
82 <para>Before starting to build GCC, remember to unset any environment
83 variables that override the default optimization flags.</para>
84
85 <para>Now prepare GCC for compilation:</para>
86
87<screen><userinput remap="configure">../configure \
88 --build=$(../config.guess) \
89 --host=$LFS_TGT \
90 --target=$LFS_TGT \
91 LDFLAGS_FOR_TARGET=-L$PWD/$LFS_TGT/libgcc \
92 --prefix=/usr \
93 --with-build-sysroot=$LFS \
94 --enable-initfini-array \
95 --disable-nls \
96 --disable-multilib \
97 --disable-decimal-float \
98 --disable-libatomic \
99 --disable-libgomp \
100 --disable-libquadmath \
101 --disable-libssp \
102 --disable-libvtv \
103 --enable-languages=c,c++</userinput></screen>
104
105 <variablelist>
106 <title>The meaning of the new configure options:</title><!-- WIP -->
107
108 <varlistentry>
109 <term><parameter>--with-build-sysroot=$LFS</parameter></term>
110 <listitem>
111 <para>Normally, using <parameter>--host</parameter> ensures that
112 a cross-compiler is used for building GCC, and that compiler knows
113 that it has to look for headers and libraries in <filename
114 class="directory">$LFS</filename>. But the build system of GCC uses
115 other tools, which are not aware of this location. This switch is
116 needed to have them find the needed files in <filename
117 class="directory">$LFS</filename>, and not on the host.</para>
118 </listitem>
119 </varlistentry>
120
121 <varlistentry>
122 <term><parameter>--target=$LFS_TGT</parameter></term>
123 <listitem>
124 <para>As we are cross-compiling GCC, it's impossible to build
125 target libraries (<filename class="libraryfile">libgcc</filename>
126 and <filename class="libraryfile">libstdc++</filename>) with the
127 compiled GCC binaries because these binaries won't run on the
128 host distro. GCC building system will attempt to use the
129 C and C++ compilers on the host distro as a workaround by default.
130 It's not supported to build GCC target libraries with a different
131 version of GCC, so using host compilers may cause building
132 failure. This parameter ensures to build the libraries with GCC
133 pass 1 and prevent the issue.</para>
134 </listitem>
135 </varlistentry>
136
137 <varlistentry>
138 <term><parameter>LDFLAGS_FOR_TARGET=...</parameter></term>
139 <listitem>
140 <para>Allow <filename class="libraryfile">libstdc++</filename> to
141 use shared <filename class="libraryfile">libgcc</filename> being
142 built in this pass, instead of the static version built in GCC
143 pass 1. This is needed for supporting C++ exception
144 handling.</para>
145 </listitem>
146 </varlistentry>
147
148 <varlistentry>
149 <term><parameter>--enable-initfini-array</parameter></term>
150 <listitem>
151 <para>This option is automatically enabled when building a native
152 compiler with a native compiler on x86. But here, we build with
153 a cross compiler, so we need to explicitly set this option.</para>
154 </listitem>
155 </varlistentry>
156
157 </variablelist>
158
159 <para>Compile the package:</para>
160
161<screen><userinput remap="make">make</userinput></screen>
162
163 <para>Install the package:</para>
164
165<screen><userinput remap="install">make DESTDIR=$LFS install</userinput></screen>
166
167 <para>As a finishing touch, create a utility symlink. Many programs and scripts
168 run <command>cc</command> instead of <command>gcc</command>, which is
169 used to keep programs generic and therefore usable on all kinds of UNIX
170 systems where the GNU C compiler is not always installed. Running
171 <command>cc</command> leaves the system administrator free to decide
172 which C compiler to install:</para>
173
174<screen><userinput remap="install">ln -sv gcc $LFS/usr/bin/cc</userinput></screen>
175
176 </sect2>
177
178 <sect2 role="content">
179 <title/>
180
181 <para>Details on this package are located in
182 <xref linkend="contents-gcc" role="."/></para>
183
184 </sect2>
185
186</sect1>
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