5.5. GCC-4.9.2 - Pass 1

5.5.1. Installation of Cross GCC

GCC now requires the GMP, MPFR and MPC packages. As these packages may not be included in your host distribution, they will be built with GCC. Unpack each package into the GCC source directory and rename the resulting directories so the GCC build procedures will automatically use them:

tar -xf ../mpfr-3.1.2.tar.xz
mv -v mpfr-3.1.2 mpfr
tar -xf ../gmp-6.0.0a.tar.xz
mv -v gmp-6.0.0 gmp
tar -xf ../mpc-1.0.2.tar.gz
mv -v mpc-1.0.2 mpc

The following command will change the location of GCC's default dynamic linker to use the one installed in /tools. It also removes /usr/include from GCC's include search path. Issue:

for file in \
 $(find gcc/config -name linux64.h -o -name linux.h -o -name sysv4.h)
do
  cp -uv $file{,.orig}
  sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \
      -e 's@/usr@/tools@g' $file.orig > $file
  echo '
#undef STANDARD_STARTFILE_PREFIX_1
#undef STANDARD_STARTFILE_PREFIX_2
#define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/"
#define STANDARD_STARTFILE_PREFIX_2 ""' >> $file
  touch $file.orig
done

In case the above seems hard to follow, let's break it down a bit. First we find all the files under the gcc/config directory that are named either linux.h, linux64.h or sysv4.h. For each file found, we copy it to a file of the same name but with an added suffix of “.orig”. Then the first sed expression prepends “/tools” to every instance of “/lib/ld”, “/lib64/ld” or “/lib32/ld”, while the second one replaces hard-coded instances of “/usr”. Next, we add our define statements which alter the default startfile prefix to the end of the file. Note that the trailing “/” in “/tools/lib/” is required. Finally, we use touch to update the timestamp on the copied files. When used in conjunction with cp -u, this prevents unexpected changes to the original files in case the commands are inadvertently run twice.

GCC doesn't detect stack protection correctly, which causes problems for the build of Glibc-2.21, so fix that by issuing the following command:

sed -i '/k prot/agcc_cv_libc_provides_ssp=yes' gcc/configure

The GCC documentation recommends building GCC outside of the source directory in a dedicated build directory:

mkdir -v ../gcc-build
cd ../gcc-build

Prepare GCC for compilation:

../gcc-4.9.2/configure                               \
    --target=$LFS_TGT                                \
    --prefix=/tools                                  \
    --with-sysroot=$LFS                              \
    --with-newlib                                    \
    --without-headers                                \
    --with-local-prefix=/tools                       \
    --with-native-system-header-dir=/tools/include   \
    --disable-nls                                    \
    --disable-shared                                 \
    --disable-multilib                               \
    --disable-decimal-float                          \
    --disable-threads                                \
    --disable-libatomic                              \
    --disable-libgomp                                \
    --disable-libitm                                 \
    --disable-libquadmath                            \
    --disable-libsanitizer                           \
    --disable-libssp                                 \
    --disable-libvtv                                 \
    --disable-libcilkrts                             \
    --disable-libstdc++-v3                           \
    --enable-languages=c,c++

Compile GCC by running:

make

Compilation is now complete. At this point, the test suite would normally be run, but, as mentioned before, the test suite framework is not in place yet. The benefits of running the tests at this point are minimal since the programs from this first pass will soon be replaced.

Install the package:

make install