A shell script to download packages for, configure, build and install a GCC cross-compiler.

build_cross_gcc

#! /bin/bash
set -e
trap 'previous_command=$this_command; this_command=$BASH_COMMAND' DEBUG
trap 'echo FAILED COMMAND: $previous_command' EXIT

#-------------------------------------------------------------------------------------------
# This script will download packages for, configure, build and install a GCC cross-compiler.
# Customize the variables (INSTALL_PATH, TARGET, etc.) to your liking before running.
# If you get an error and need to resume the script from some point in the middle,
# just delete/comment the preceding lines before running it again.
#
# See: http://preshing.com/20141119/how-to-build-a-gcc-cross-compiler
#-------------------------------------------------------------------------------------------

INSTALL_PATH=/opt/cross
TARGET=aarch64-linux
USE_NEWLIB=0
LINUX_ARCH=arm64
CONFIGURATION_OPTIONS="--disable-multilib" # --disable-threads --disable-shared
PARALLEL_MAKE=-j4
BINUTILS_VERSION=binutils-2.24
GCC_VERSION=gcc-4.9.2
LINUX_KERNEL_VERSION=linux-3.17.2
GLIBC_VERSION=glibc-2.20
MPFR_VERSION=mpfr-3.1.2
GMP_VERSION=gmp-6.0.0a
MPC_VERSION=mpc-1.0.2
ISL_VERSION=isl-0.12.2
CLOOG_VERSION=cloog-0.18.1
export PATH=$INSTALL_PATH/bin:$PATH

# Download packages
export http_proxy=$HTTP_PROXY https_proxy=$HTTP_PROXY ftp_proxy=$HTTP_PROXY
wget -nc https://ftp.gnu.org/gnu/binutils/$BINUTILS_VERSION.tar.gz
wget -nc https://ftp.gnu.org/gnu/gcc/$GCC_VERSION/$GCC_VERSION.tar.gz
if [ $USE_NEWLIB -ne 0 ]; then
    wget -nc -O newlib-master.zip https://github.com/bminor/newlib/archive/master.zip || true
    unzip -qo newlib-master.zip
else
    wget -nc https://www.kernel.org/pub/linux/kernel/v3.x/$LINUX_KERNEL_VERSION.tar.xz
    wget -nc https://ftp.gnu.org/gnu/glibc/$GLIBC_VERSION.tar.xz
fi
wget -nc https://ftp.gnu.org/gnu/mpfr/$MPFR_VERSION.tar.xz
wget -nc https://ftp.gnu.org/gnu/gmp/$GMP_VERSION.tar.xz
wget -nc https://ftp.gnu.org/gnu/mpc/$MPC_VERSION.tar.gz
wget -nc ftp://gcc.gnu.org/pub/gcc/infrastructure/$ISL_VERSION.tar.bz2
wget -nc ftp://gcc.gnu.org/pub/gcc/infrastructure/$CLOOG_VERSION.tar.gz

# Extract everything
for f in *.tar*; do tar xfk $f; done

# Make symbolic links
cd $GCC_VERSION
ln -sf `ls -1d ../mpfr-*/` mpfr
ln -sf `ls -1d ../gmp-*/` gmp
ln -sf `ls -1d ../mpc-*/` mpc
ln -sf `ls -1d ../isl-*/` isl
ln -sf `ls -1d ../cloog-*/` cloog
cd ..

# Step 1. Binutils
mkdir -p build-binutils
cd build-binutils
../$BINUTILS_VERSION/configure --prefix=$INSTALL_PATH --target=$TARGET $CONFIGURATION_OPTIONS
make $PARALLEL_MAKE
make install
cd ..

# Step 2. Linux Kernel Headers
if [ $USE_NEWLIB -eq 0 ]; then
    cd $LINUX_KERNEL_VERSION
    make ARCH=$LINUX_ARCH INSTALL_HDR_PATH=$INSTALL_PATH/$TARGET headers_install
    cd ..
fi

# Step 3. C/C++ Compilers
mkdir -p build-gcc
cd build-gcc
if [ $USE_NEWLIB -ne 0 ]; then
    NEWLIB_OPTION=--with-newlib
fi
../$GCC_VERSION/configure --prefix=$INSTALL_PATH --target=$TARGET --enable-languages=c,c++ $CONFIGURATION_OPTIONS $NEWLIB_OPTION
make $PARALLEL_MAKE all-gcc
make install-gcc
cd ..

if [ $USE_NEWLIB -ne 0 ]; then
    # Steps 4-6: Newlib
    mkdir -p build-newlib
    cd build-newlib
    ../newlib-master/configure --prefix=$INSTALL_PATH --target=$TARGET $CONFIGURATION_OPTIONS
    make $PARALLEL_MAKE
    make install
    cd ..
else
    # Step 4. Standard C Library Headers and Startup Files
    mkdir -p build-glibc
    cd build-glibc
    ../$GLIBC_VERSION/configure --prefix=$INSTALL_PATH/$TARGET --build=$MACHTYPE --host=$TARGET --target=$TARGET --with-headers=$INSTALL_PATH/$TARGET/include $CONFIGURATION_OPTIONS libc_cv_forced_unwind=yes
    make install-bootstrap-headers=yes install-headers
    make $PARALLEL_MAKE csu/subdir_lib
    install csu/crt1.o csu/crti.o csu/crtn.o $INSTALL_PATH/$TARGET/lib
    $TARGET-gcc -nostdlib -nostartfiles -shared -x c /dev/null -o $INSTALL_PATH/$TARGET/lib/libc.so
    touch $INSTALL_PATH/$TARGET/include/gnu/stubs.h
    cd ..

    # Step 5. Compiler Support Library
    cd build-gcc
    make $PARALLEL_MAKE all-target-libgcc
    make install-target-libgcc
    cd ..

    # Step 6. Standard C Library & the rest of Glibc
    cd build-glibc
    make $PARALLEL_MAKE
    make install
    cd ..
fi

# Step 7. Standard C++ Library & the rest of GCC
cd build-gcc
make $PARALLEL_MAKE all
make install
cd ..

trap - EXIT
echo 'Success!'

Is it possible to build multi lib gcc i.e. with aarch64 and arm?

This doesn't work for me trying to build gcc-4.8.5. It fails on configuring glibc (2.12.2) as it is using the newly built cross-compiled-gcc which cannot find stdio.h. I can resolve this by not exporting the PATH to the new binaries but then the csu binaries built will be for the host architecture. Not really sure how to resolve it.

Anyone trying to use something other than Linux as the build/host platform may be helped by looking at my fork of this script.
My Fork

I used MSys2 64 bit (a Cygwin fork) under Win7 64 bit; I yet to test the cross compiler produced; did it as a learning exercise.
I have no need to use it; but, likely will in a few months.

Edit2: Once, I deleted the installed files my version of the script stopped building with gcc/glibc errors.

Tim S.