6.18.1. Installation of GCC
As in the first build of GCC, the GMP, MPFR, and MPC packages are required. Unpack the tarballs and move them into the required directories:
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
If you are building on x86_64, change the default directory name for 64-bit libraries to “lib”:
case $(uname -m) in
x86_64)
sed -e '/m64=/s/lib64/lib/' \
-i.orig gcc/config/i386/t-linux64
;;
esac
Override the build rules of the libgcc and libstdc++ headers to allow building these libraries with POSIX threads support:
sed '/thread_header =/s/@.*@/gthr-posix.h/' \
-i libgcc/Makefile.in libstdc++-v3/include/Makefile.in
Create a separate build directory again:
Before starting to build GCC, remember to unset any environment variables that override the default optimization flags.
Now prepare GCC for compilation:
../configure \
--build=$(../config.guess) \
--host=$LFS_TGT \
--target=$LFS_TGT \
--prefix=/usr \
--with-build-sysroot=$LFS \
--enable-default-pie \
--enable-default-ssp \
--disable-nls \
--disable-multilib \
--disable-libatomic \
--disable-libgomp \
--disable-libquadmath \
--disable-libsanitizer \
--disable-libssp \
--disable-libvtv \
--enable-languages=c,c++ \
LDFLAGS_FOR_TARGET=-L$PWD/$LFS_TGT/libgcc
The meaning of the new configure options:
--with-build-sysroot=$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 .
However, the build system for GCC uses additional tools which are not aware of this location. This switch is needed so those tools will find the needed files in $LFS , and not on the host.
--target=$LFS_TGT
We are cross-compiling GCC, so it's impossible to build target libraries ( libgcc and libstdc++ ) with the GCC binaries compiled in this pass—those binaries won't run on the host. The GCC build system will attempt to use the host's C and C++ compilers as a workaround by default. Building the GCC target libraries with a different version of GCC is not supported, so using the host's compilers may cause the build to fail. This parameter ensures the libraries are built by GCC pass 1.
LDFLAGS_FOR_TARGET=...
Allow libstdc++ to use the libgcc being built in this pass, instead of the previous version built in gcc-pass1. The previous version cannot properly support C++ exception handling because it was built without libc support.
--disable-libsanitizer
Disable GCC sanitizer runtime libraries. They are not needed for the temporary installation. In gcc-pass1 it was implied by --disable-libstdcxx , and now we can explicitly pass it.
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 8.29.2, “Contents of GCC.”
