5.2. Embryo Toolchain

We will be building Binutils and GCC from a combined source tree using the GCC Top Level Makefile. For more information about the Top Level Makefile build system see: http://gcc.gnu.org/install/ and http://gcc.gnu.org/wiki/Top-Level Bootstrap/.

This system will allow us to perform a 3 stage bootstrap, which will compile Binutils and GCC three times, using the latest build of each package for each new build. The resulting toolchain will be completely free from the host system's toolchain features or limitations, resulting in a sterile place to begin our HLFS system.

Unpack both the binutils-2.17 and gcc-core-4.1.2 source tarballs but do not change directory. Then combine them in the same directory with the following commands:

mv gcc-4.1.2/ embryo-toolchain
mv -v binutils-2.17 embryo-toolchain/
cd embryo-toolchain/
ln -vs binutils-2.17/{bfd,binutils,gas,gprof,ld,opcodes} .

The binutils-2.17 directories are symbolically linked because the Binutils include directory must remain available, and seperate from GCC's include directory, for binutils-2.17 to compile correctly.

Binutils-2.17 and GCC-4.1.2 do not use Posix compliant command syntax with the head and tail commands. Although this is not critical it should be fixed. Do so with the following commands:

cp -vi ltcf-c.sh{,.orig}
sed 's/head -1/head -n 1/g' ltcf-c.sh.orig > ltcf-c.sh
cp -vi ltcf-gcj.sh{,.orig}
sed 's/head -1/head -n 1/g' ltcf-gcj.sh.orig > ltcf-gcj.sh
cp -vi configure{,.orig}
sed 's/tail +16c/tail -c +16/g' configure.orig > configure
cp -vi gas/Makefile.in{,.orig}
sed 's/tail +16c/tail -c +16/g' gas/Makefile.in.orig > gas/Makefile.in
cp -vi gcc/Makefile.in{,.orig}
sed 's/tail +16c/tail -c +16/g' gcc/Makefile.in.orig > gcc/Makefile.in
cp -vi gcc/configure{,.orig}
sed 's/tail -3/tail -n 3/g' gcc/configure.orig > gcc/configure
cp -vi ld/testsuite/ld-bootstrap/bootstrap.exp{,.orig}
sed 's/tail +140/tail -n +140/g' \
    ld/testsuite/ld-bootstrap/bootstrap.exp.orig \
      > ld/testsuite/ld-bootstrap/bootstrap.exp

We want to make this a Position Independent Code (PIC) compiler so that everything we compile with this GCC will be built the same way in the next chapter. For example Glibc's utilities will use different assembly code if the compiler defines PIC. Packages like Glibc and Libibery do not use the “--with-pic” configure switch to add -fPIC to compiler flags. This sed command will hardcode -fPIC into GCC's specs:

cp -vi gcc/config/i386/linux.h{,.orig}
sed 's/^\(#define CC1_SPEC.*\)\("\)$/\1 %{fno-pic|fpic|fPIC:;:-fPIC}\2/' \
    gcc/config/i386/linux.h.orig > gcc/config/i386/linux.h

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

mkdir -v ../embryo-build/
cd ../embryo-build/

Prepare the toolchain for compilation:

../embryo-toolchain/configure --prefix=/tools \
    --with-local-prefix=/tools --with-pic --disable-nls \
    --enable-languages=c --enable-checking \
    --enable-werror --enable-bootstrap

Compile the toolchain with a 3 stage bootstrap:

make

Install the toolchain:

make install

Create a symlink from gcc to cc. Some packages will need this:

ln -vs gcc /tools/bin/cc

Then, prepare the linker for the “Adjusting” phase later on:

ln -vs stage3-bfd/ bfd
ln -vs stage3-libiberty/ libiberty
cp -va stage3-ld/ tools-ld
make -C tools-ld/ clean
make -C tools-ld/ LIB_PATH=/tools/lib CC=/tools/bin/gcc
make -C tools-ld/ CC=/tools/bin/gcc EXEEXT=-new install-exec-local