gcc-pass2.xml 9.0 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. <sect1 id="ch-tools-gcc-pass2" role="wrap">
  8. <?dbhtml filename="gcc-pass2.html"?>
  9. <sect1info condition="script">
  10. <productname>gcc-pass2</productname>
  11. <productnumber>&gcc-version;</productnumber>
  12. <address>&gcc-url;</address>
  13. </sect1info>
  14. <title>GCC-&gcc-version; - Pass 2</title>
  15. <indexterm zone="ch-tools-gcc-pass2">
  16. <primary sortas="a-GCC">GCC</primary>
  17. <secondary>tools, pass 2</secondary>
  18. </indexterm>
  19. <sect2 role="package">
  20. <title/>
  21. <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
  22. href="../chapter06/gcc.xml"
  23. xpointer="xpointer(/sect1/sect2[1]/para[1])"/>
  24. <segmentedlist>
  25. <segtitle>&buildtime;</segtitle>
  26. <segtitle>&diskspace;</segtitle>
  27. <seglistitem>
  28. <seg>&gcc-ch5p2-sbu;</seg>
  29. <seg>&gcc-ch5p2-du;</seg>
  30. </seglistitem>
  31. </segmentedlist>
  32. </sect2>
  33. <sect2 role="installation">
  34. <title>Installation of GCC</title>
  35. <para>Our first build of GCC has installed a couple of internal system
  36. headers. Normally one of them, <filename>limits.h</filename>, will in turn
  37. include the corresponding system <filename>limits.h</filename> header, in
  38. this case, <filename>/tools/include/limits.h</filename>. However, at the
  39. time of the first build of gcc <filename>/tools/include/limits.h</filename>
  40. did not exist, so the internal header that GCC installed is a partial,
  41. self-contained file and does not include the extended features of the
  42. system header. This was adequate for building the temporary libc, but this
  43. build of GCC now requires the full internal header. Create a full version
  44. of the internal header using a command that is identical to what the GCC
  45. build system does in normal circumstances:</para>
  46. <screen><userinput remap="pre">cat gcc/limitx.h gcc/glimits.h gcc/limity.h &gt; \
  47. `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include-fixed/limits.h</userinput></screen>
  48. <!--
  49. <para>For x86 machines, the limited number of registers is a bottleneck
  50. for the system. Free one up by not using a frame pointer that is not
  51. needed:</para>
  52. <screen><userinput remap="pre">case `uname -m` in
  53. i?86) sed -i 's/^T_CFLAGS =$/&amp; -fomit-frame-pointer/' gcc/Makefile.in ;;
  54. esac</userinput></screen>
  55. -->
  56. <para>Once again, change the location of GCC's default dynamic linker to
  57. use the one installed in <filename
  58. class="directory">/tools</filename>.</para>
  59. <screen><userinput remap="pre">for file in gcc/config/{linux,i386/linux{,64}}.h
  60. do
  61. cp -uv $file{,.orig}
  62. sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&amp;@g' \
  63. -e 's@/usr@/tools@g' $file.orig &gt; $file
  64. echo '
  65. #undef STANDARD_STARTFILE_PREFIX_1
  66. #undef STANDARD_STARTFILE_PREFIX_2
  67. #define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
  68. #define STANDARD_STARTFILE_PREFIX_2 ""' &gt;&gt; $file
  69. touch $file.orig
  70. done</userinput></screen>
  71. <para>If building on x86_64, change the default directory name for 64-bit
  72. libraries to <quote>lib</quote>:</para>
  73. <screen><userinput remap="pre">case $(uname -m) in
  74. x86_64)
  75. sed -e '/m64=/s/lib64/lib/' \
  76. -i.orig gcc/config/i386/t-linux64
  77. ;;
  78. esac</userinput></screen>
  79. <para>As in the first build of GCC it requires the GMP, MPFR and MPC
  80. packages. Unpack the tarballs and move them into the required directory
  81. names:</para>
  82. <screen><userinput remap="pre">tar -xf ../mpfr-&mpfr-version;.tar.xz
  83. mv -v mpfr-&mpfr-version; mpfr
  84. tar -xf ../gmp-&gmp-version;.tar.xz
  85. mv -v gmp-&gmp-version; gmp
  86. tar -xf ../mpc-&mpc-version;.tar.gz
  87. mv -v mpc-&mpc-version; mpc</userinput></screen>
  88. <!--
  89. <para>As in the first build of GCC, fix a problem identified upstream:</para>
  90. <screen><userinput remap="pre">sed -i 's/if \((code.*))\)/if (\1 \&amp;\&amp; \!DEBUG_INSN_P (insn))/' gcc/sched-deps.c</userinput></screen>
  91. -->
  92. <para>Create a separate build directory again:</para>
  93. <screen><userinput remap="pre">mkdir -v build
  94. cd build</userinput></screen>
  95. <para>Before starting to build GCC, remember to unset any environment
  96. variables that override the default optimization flags.</para>
  97. <para>Now prepare GCC for compilation:</para>
  98. <screen><userinput remap="configure">CC=$LFS_TGT-gcc \
  99. CXX=$LFS_TGT-g++ \
  100. AR=$LFS_TGT-ar \
  101. RANLIB=$LFS_TGT-ranlib \
  102. ../configure \
  103. --prefix=/tools \
  104. --with-local-prefix=/tools \
  105. --with-native-system-header-dir=/tools/include \
  106. --enable-languages=c,c++ \
  107. --disable-libstdcxx-pch \
  108. --disable-multilib \
  109. --disable-bootstrap \
  110. --disable-libgomp</userinput></screen>
  111. <variablelist>
  112. <title>The meaning of the new configure options:</title>
  113. <varlistentry>
  114. <term><parameter>--enable-languages=c,c++</parameter></term>
  115. <listitem>
  116. <para>This option ensures that both the C and C++ compilers are
  117. built.</para>
  118. </listitem>
  119. </varlistentry>
  120. <varlistentry>
  121. <term><parameter>--disable-libstdcxx-pch</parameter></term>
  122. <listitem>
  123. <para>Do not build the pre-compiled header (PCH) for
  124. <filename class="libraryfile">libstdc++</filename>. It takes up a
  125. lot of space, and we have no use for it.</para>
  126. </listitem>
  127. </varlistentry>
  128. <varlistentry>
  129. <term><parameter>--disable-bootstrap</parameter></term>
  130. <listitem>
  131. <para>For native builds of GCC, the default is to do a "bootstrap"
  132. build. This does not just compile GCC, but compiles it several times.
  133. It uses the programs compiled in a first round to compile itself a
  134. second time, and then again a third time. The second and third
  135. iterations are compared to make sure it can reproduce itself
  136. flawlessly. This also implies that it was compiled correctly.
  137. However, the LFS build method should provide a solid compiler
  138. without the need to bootstrap each time.</para>
  139. </listitem>
  140. </varlistentry>
  141. </variablelist>
  142. <para>Compile the package:</para>
  143. <screen><userinput remap="make">make</userinput></screen>
  144. <para>Install the package:</para>
  145. <screen><userinput remap="install">make install</userinput></screen>
  146. <para>As a finishing touch, create a symlink. Many programs and scripts
  147. run <command>cc</command> instead of <command>gcc</command>, which is
  148. used to keep programs generic and therefore usable on all kinds of UNIX
  149. systems where the GNU C compiler is not always installed. Running
  150. <command>cc</command> leaves the system administrator free to decide
  151. which C compiler to install:</para>
  152. <screen><userinput remap="install">ln -sv gcc /tools/bin/cc</userinput></screen>
  153. <caution>
  154. <para>At this point, it is imperative to stop and ensure that the basic
  155. functions (compiling and linking) of the new toolchain are working as
  156. expected. To perform a sanity check, run the following commands:</para>
  157. <screen><userinput>echo 'int main(){}' &gt; dummy.c
  158. cc dummy.c
  159. readelf -l a.out | grep ': /tools'</userinput></screen>
  160. <para>If everything is working correctly, there should be no errors,
  161. and the output of the last command will be of the form:</para>
  162. <screen><computeroutput>[Requesting program interpreter: /tools/lib64/ld-linux-x86-64.so.2]</computeroutput></screen>
  163. <para>Note that the dynamic linker will be /tools/lib/ld-linux.so.2
  164. for 32-bit machines.</para>
  165. <para>If the output is not shown as above or there was no output at all,
  166. then something is wrong. Investigate and retrace the steps to find out
  167. where the problem is and correct it. This issue must be resolved before
  168. continuing on. First, perform the sanity check again, using
  169. <command>gcc</command> instead of <command>cc</command>. If this works,
  170. then the <filename class="symlink">/tools/bin/cc</filename> symlink is
  171. missing. Install the symlink as per above.
  172. Next, ensure that the <envar>PATH</envar> is correct. This
  173. can be checked by running <command>echo $PATH</command> and verifying that
  174. <filename class="directory">/tools/bin</filename> is at the head of the
  175. list. If the <envar>PATH</envar> is wrong it could mean that you are not
  176. logged in as user <systemitem class="username">lfs</systemitem> or that
  177. something went wrong back in <xref linkend="ch-tools-settingenviron"
  178. role="."/></para>
  179. <para>Once all is well, clean up the test files:</para>
  180. <screen><userinput>rm -v dummy.c a.out</userinput></screen>
  181. </caution>
  182. </sect2>
  183. <sect2 role="content">
  184. <title/>
  185. <para>Details on this package are located in
  186. <xref linkend="contents-gcc" role="."/></para>
  187. </sect2>
  188. </sect1>