1 | <sect2><title> </title><para> </para></sect2>
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2 |
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3 | <sect2>
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4 | <title>Installation of GCC</title>
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5 |
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6 | <para>We won't be needing a C++ compiler until Chapter 6. So, only
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7 | the gcc-core tarball needs to be unpacked at this time.</para>
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8 |
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9 | <para>This package is known to behave badly when you have changed its
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10 | default optimization flags (including the -march and -mcpu options).
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11 | Therefore, if you have defined any environment variables that override
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12 | default optimizations, such as CFLAGS and CXXFLAGS, we recommend unsetting
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13 | or modifying them when building GCC.</para>
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14 |
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15 | <para><screen><userinput>patch -Np1 -i ../gcc-&gcc-version;-mmap_test.patch
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16 | patch -Np1 -i ../gcc-&gcc-version;-no_fixincludes.patch
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17 | patch -Np1 -i ../gcc-&gcc-version;-libstdc++_no_debug.patch
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18 | patch -Np1 -i ../gcc-&gcc-version;-libgcc_no_debug.patch</userinput></screen></para>
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19 |
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20 | <para>It is recommended by the GCC installation documentation to build
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21 | GCC outside of the source directory in a dedicated directory:</para>
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22 |
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23 | <para><screen><userinput>mkdir ../gcc-build
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24 | cd ../gcc-build</userinput></screen></para>
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25 |
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26 | <para>Prepare GCC to be compiled:</para>
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27 |
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28 | <para><screen><userinput>CFLAGS="-O2 -pipe" \
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29 | ../gcc-&gcc-version;/configure --prefix=/stage1 \
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30 | --with-local-prefix=/stage1 \
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31 | --disable-nls --enable-shared </userinput></screen></para>
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32 |
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33 | <para>The meaning of the configure options are:</para>
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34 |
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35 | <itemizedlist>
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36 | <listitem><para><userinput>--prefix=/static</userinput>: This is NOT a
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37 | typo. GCC hard codes some paths while compiling and so we need to pass
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38 | <filename class="directory">/static</filename> as the prefix during the
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39 | configure stage. We will pass the real installation prefix (<filename
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40 | class="directory">$LFS/static</filename>) during the installation
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41 | stage later on.</para></listitem>
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42 |
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43 | <listitem><para><userinput>--disable-shared</userinput>: This prevents the
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44 | build of dynamic libraries. They are useless to us at the moment. We'll
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45 | create them when we reinstall GCC in chapter 6.</para></listitem>
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46 |
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47 | <listitem><para><userinput>--with-as=$LFS/static/bin/as and
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48 | --with-ld=$LFS/static/bin/ld</userinput>: GCC can be miscompiled if your
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49 | host distribution's Binutils package is quite old. We need a good working
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50 | static GCC until we reinstall GCC later in chapter 6. So by using
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51 | <filename>as</filename> and <filename>ld</filename> from the Binutils
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52 | package we compiled earlier in this chapter we ensure that GCC will work
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53 | correctly.</para></listitem>
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54 | </itemizedlist>
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55 |
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56 | <para>Continue with compiling the package:</para>
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57 |
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58 | <para><screen><userinput>make BOOT_LDFLAGS="-static -s" \
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59 | BOOT_CFLAGS="-O2 -pipe" \
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60 | STAGE1_CFLAGS="-pipe" bootstrap</userinput></screen></para>
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61 |
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62 | <para>The meaning of the make options are:</para>
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63 |
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64 | <itemizedlist>
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65 | <listitem><para><userinput>BOOT_LDFLAGS="-static"</userinput>: This is
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66 | GCC's equivalent to make LDFLAGS="-static" as we use with other packages to
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67 | compile them statically.</para></listitem>
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68 |
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69 | <listitem><para><userinput>bootstrap</userinput>: The
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70 | <emphasis>bootstrap</emphasis> target doesn't just compile GCC, but it
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71 | compiles GCC a second time. It uses the first compiled programs to compile
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72 | itself a second and third time to make sure the compiler was compiled properly
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73 | and can compile itself properly.</para></listitem>
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74 | </itemizedlist>
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75 |
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76 | <para>And finish off installing the package:</para>
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77 |
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78 | <para><screen><userinput>make install</userinput></screen></para>
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79 |
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80 | <para>The meaning of the make option is:</para>
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81 |
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82 | <itemizedlist>
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83 | <listitem><para><userinput>install-no-fixedincludes</userinput>: This prevents
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84 | the fixincludes script from running. Preventing this is necessary because
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85 | under normal circumstances the GCC installation will run the fixincludes
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86 | script which scans your system for header files that need to be fixed. It
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87 | might find that the Glibc header files of your host system need to be fixed.
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88 | If so, it will fix them and put them in
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89 | <filename>$LFS/static/lib/gcc-lib/i686-pc-linux-gnu/3.2</filename>. Later on
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90 | in chapter 6 you will install Glibc which will put its header files in
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91 | <filename>/usr/include</filename>. Next you will install other programs that
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92 | use the Glibc headers and GCC will look in
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93 | <filename>/static/lib/gcc-lib</filename> before looking in
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94 | <filename>/usr/include</filename>, with the result of finding and using the
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95 | fixed Glibc header files from your host distribution, which are probably
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96 | incompatible with the Glibc version actually used on the LFS
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97 | system.</para></listitem>
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98 | </itemizedlist>
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99 |
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100 | <para>As the finishing touch we'll create the <filename
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101 | class="symlink">$LFS/static/bin/cc</filename> symlink. A lot of programs
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102 | and scripts try to run <userinput>cc</userinput> instead of
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103 | <userinput>gcc</userinput> This is to keep programs generic and usable on
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104 | all kinds of Unix systems. Not everybody has GNU CC installed. Just running
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105 | <userinput>cc</userinput> (C Compiler) leaves the user free to decide which
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106 | C compiler to install. The symlink will point to the system's default
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107 | compiler.</para>
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108 |
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109 | <para><screen><userinput>ln -sf gcc /stage1/bin/cc</userinput></screen></para>
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110 |
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111 | </sect2>
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112 |
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