Details on this package are located in Section 8.22.2, “Contents of GCC.”
The GCC package contains the GNU compiler collection, which includes the C and C++ compilers.
As in the first build of GCC, the GMP, MPFR, and MPC packages are required. Unpack the tarballs and move them into the required directory names:
tar -xf ../mpfr-4.0.2.tar.xz mv -v mpfr-4.0.2 mpfr tar -xf ../gmp-6.2.0.tar.xz mv -v gmp-6.2.0 gmp tar -xf ../mpc-1.1.0.tar.gz mv -v mpc-1.1.0 mpc
If building on x86_64, change 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
Fix an issue with GCC-10.1 when building with a cross compiler:
patch -Np1 -i ../gcc-10.1.0-cet_fix-1.patch
Create a separate build directory again:
mkdir -v build cd build
Create a symlink that allows libgcc to be built with posix threads support:
mkdir -pv $LFS_TGT/libgcc ln -s ../../../libgcc/gthr-posix.h $LFS_TGT/libgcc/gthr-default.h
Before starting to build GCC, remember to unset any environment variables that override the default optimization flags.
Now prepare GCC for compilation:
../configure \
--build=$(../config.guess) \
--host=$LFS_TGT \
--prefix=/usr \
CC_FOR_TARGET=$LFS_TGT-gcc \
--with-build-sysroot=$LFS \
--enable-initfini-array \
--disable-nls \
--disable-multilib \
--disable-decimal-float \
--disable-libatomic \
--disable-libgomp \
--disable-libquadmath \
--disable-libssp \
--disable-libvtv \
--disable-libstdcxx \
--enable-languages=c,c++
The meaning of the new configure options:
-with-build-sysroot=$LFS
Normally, using --host ensures that a
cross-compiler is used for building GCC, and that compiler
knows that it has to look for headers and libraries in
$LFS. But the build system of
GCC uses other tools, which are not aware of this location.
This switch is needed to have them find the needed files in
$LFS, and not on the host.
--enable-initfini-array
This option is automatically enabled when building a native compiler with a native compiler on x86. But here, we build with a cross compiler, so we need to explicitely set this option.
Compile the package:
make
Install the package:
make DESTDIR=$LFS install
As a finishing touch, create a utility symlink. Many programs and scripts run cc instead of gcc, which is used to keep programs generic and therefore usable on all kinds of UNIX systems where the GNU C compiler is not always installed. Running cc leaves the system administrator free to decide which C compiler to install:
ln -sv gcc $LFS/usr/bin/cc
Details on this package are located in Section 8.22.2, “Contents of GCC.”