GCC-15.2.0 - Pass 1

Installation of Cross GCC

GCC 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:

Note

There are frequent misunderstandings about this chapter. The procedures are the same as every other chapter, as explained earlier ('buildinstr'). First, extract the gcc-15.2.0 tarball from the sources directory, and then change to the directory created. Only then should you proceed with the instructions below.

tar -xf ../mpfr-4.2.2.tar.xz
mv -v mpfr-4.2.2 mpfr
tar -xf ../gmp-6.3.0.tar.xz
mv -v gmp-6.3.0 gmp
tar -xf ../mpc-1.3.1.tar.gz
mv -v mpc-1.3.1 mpc

On x86_64 hosts, set the default directory name for 64-bit libraries to “lib”:

case $(uname -m) in
  x86_64)
    sed -e '/m64=/s/lib64/lib/' \
        -i.orig gcc/config/i386/t-linux64
 ;;
esac

Note

This example demonstrates the use of the -i.orig switch. It makes the sed copy the t-linux64 file to t-linux64.orig, and then edit the original t-linux64 file inplace. So you may run diff -u gcc/config/i386/t-linux64{.orig,} to visualize the change done by the sed command afterwards. We'll simply use -i (which just edits the original file inplace without copying it) for all other packages in the book, but you can change it to -i.orig in any case you want to keep a copy of the original file.

The GCC documentation recommends building GCC in a dedicated build directory:

mkdir -v build
cd       build

Prepare GCC for compilation:

../configure                  \
    --target=$LFS_TGT         \
    --prefix=$LFS/tools       \
    --with-glibc-version=2.42 \
    --with-sysroot=$LFS       \
    --with-newlib             \
    --without-headers         \
    --enable-default-pie      \
    --enable-default-ssp      \
    --disable-nls             \
    --disable-shared          \
    --disable-multilib        \
    --disable-threads         \
    --disable-libatomic       \
    --disable-libgomp         \
    --disable-libquadmath     \
    --disable-libssp          \
    --disable-libvtv          \
    --disable-libstdcxx       \
    --enable-languages=c,c++

Compile GCC by running:

make

Install the package:

make install

This build of GCC has installed a couple of internal system headers. Normally one of them, limits.h, would in turn include the corresponding system limits.h header, in this case, $LFS/usr/include/limits.h. However, at the time of this build of GCC $LFS/usr/include/limits.h does not exist, so the internal header that has just been installed is a partial, self-contained file and does not include the extended features of the system header. This is adequate for building Glibc, but the full internal header will be needed later. Create a full version of the internal header using a command that is identical to what the GCC build system does in normal circumstances:

Note

The command below shows an example of nested command substitution using two methods: backquotes and a $() construct. It could be rewritten using the same method for both substitutions, but is shown this way to demonstrate how they can be mixed. Generally the $() method is preferred.

cd ..
cat gcc/limitx.h gcc/glimits.h gcc/limity.h > \
  `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include/limits.h