Building a Cross Compiler on FreeBSD

I’m currently trying to build a cross compiler (and other required tools) on FreeBSD. The compiler will run on FreeBSD/amd64 and should produce i386 binaries. This wouldn’t be too hard since that task can easily be accomplished by using the FreeBSD source tree. However, I need the toolchain to produce binaries in the PE/COFF format instead of the default ELF format.

Building the toolchain is somewhat tricky, at least I found it to be poorly documented. But maybe I just looked in the wrong places. Building the toolchain requires:

  • Building binutils.
  • Locating some header files.
  • Building the compiler.
  • Building a C Library.
  • Building the compiler again so it uses the C library that was just built.

For my needs, I found that the last two steps weren’t needed. I wrote a script that downloads the sources, extracts the archives and builds the toolchain. Here’s the script in full quote (I really wish there was a way to upload files to this thing):

#/bin/sh

#
# Copyright (c) 2008 Philip Schulz 
#

#
# This script downloads, builds and installs GCC and GNU Binutils that can
# produce x86 binaries in PE/COFF Format. The cross toolchain needs some headers
# that aren't usually present on the host system. However, those headers can be
# obtained from the cygwin sources, that's why a snapshot of the cygwin sources
# is downloaded.
#
# After the script finishes, the tools will be located at
# ${PREFIX}/${TARGET_ARCH}/bin. Some other binaries will be installed in
# ${PREFIX}/bin with their own prefix of ${TARGET_ARCH} but I don't know that
# they are for.
#

# Prefix where the Cross-Tools will live
PREFIX="${PREFIX:-/opt}"

# Target architecture.
TARGET_CPU="${TARGET_CPU:-i386}"
TARGET_ARCH=${TARGET_CPU}-tiano-pe

# Program that can fetch the files.
FETCH_COMMAND="/usr/bin/ftp -V"

# GNU Make
GNU_MAKE=`which gmake`

################################################################################
#
# GCC settings.
#
################################################################################
# What version of GCC will be fetched, built and installed 
GCC_VERSION=gcc-4.2.3
# What mirror to use.
GCC_MIRROR=ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/ftp.gnu.org
# File name of the GCC sources. Should probably not be changed.
GCC_ARCHIVE=$GCC_VERSION.tar.bz2
# Where the GCC Sources can be fetched from. Should probably not be changed.
GCC_URL=$GCC_MIRROR/gcc/$GCC_VERSION/$GCC_ARCHIVE
# Arguments for the GCC configure script. Should probably not be changed.
GCC_CONFIGURE_ARGS="--prefix=${PREFIX} --target=${TARGET_ARCH} "
GCC_CONFIGURE_ARGS+="--with-gnu-as --with-gnu-ld --with-newlib "
GCC_CONFIGURE_ARGS+="--disable-libssp --disable-nls --enable-languages=c "
GCC_CONFIGURE_ARGS+="--program-prefix=${TARGET_ARCH}- "
GCC_CONFIGURE_ARGS+="--program-suffix=-4.2.3 "


################################################################################
#
# Binutils settings.
#
################################################################################
# What version of the GNU binutils will be fetched, build and installed
BINUTILS_VERSION=binutils-2.18
# What mirror to use.
BINUTILS_MIRROR=ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/ftp.gnu.org
# File name of the binutils sources. Should probably not be changed.
BINUTILS_ARCHIVE=$BINUTILS_VERSION.tar.gz
# Where the GCC Sources can be fetched from. Should probably not be changed.
BINUTILS_URL=$BINUTILS_MIRROR/binutils/$BINUTILS_ARCHIVE
# Arguments for the GCC configure script. Should probably not be changed.
BINUTILS_CONFIGURE_ARGS="--prefix=${PREFIX} --target=${TARGET_ARCH} "
BINUTILS_CONFIGURE_ARGS+="--disable-nls "

################################################################################
#
# Cygwin settings.
#
################################################################################
CYGWIN_SNAPSHOT=20080129
CYGWIN_ARCHIVE=cygwin-src-${CYGWIN_SNAPSHOT}.tar.bz2
CYGWIN_MIRROR=http://cygwin.com/
CYGWIN_URL=${CYGWIN_MIRROR}snapshots/${CYGWIN_ARCHIVE}
CYGWIN_DIR=cygwin-snapshot-${CYGWIN_SNAPSHOT}-1

################################################################################
#
# Batch code.
#
################################################################################
#
# Fetches the files.
#
do_fetch() {
        if [ ! ( -f $GCC_ARCHIVE ) ] ; then
                echo "Fetching ${GCC_URL}"
                ${FETCH_COMMAND} ${GCC_URL}
        else
                echo $GCC_ARCHIVE already locally present.
        fi

        if [ ! ( -f $CYGWIN_ARCHIVE ) ] ; then
                echo "Fetching ${CYGWIN_URL}"
                ${FETCH_COMMAND} ${CYGWIN_URL}
        else
                echo $CYGWIN_ARCHIVE already locally present.
        fi

        if [ ! ( -f $BINUTILS_ARCHIVE ) ] ; then
                echo "Fetching ${BINUTILS_URL}"
                ${FETCH_COMMAND} ${BINUTILS_URL}
        else
                echo $BINUTILS_ARCHIVE already locally present.
        fi
}

#
# Extracts the archives.
#
do_extract() {
        # Remove already extracted files first.
        rm -rf ${GCC_VERSION}
        rm -rf ${CYGWIN_DIR}
        rm -rf ${BINUTILS_VERSION}

        # Extract the archives
        if [ -f $GCC_ARCHIVE ] ; then
                echo "Extracting ${GCC_ARCHIVE}"
                tar -jxf ${GCC_ARCHIVE}
        fi

        if [ -f $CYGWIN_ARCHIVE ] ; then
                echo "Extracting ${CYGWIN_ARCHIVE}"
                tar -jxf ${CYGWIN_ARCHIVE}
        fi

        if [ -f $BINUTILS_ARCHIVE ] ; then
                echo "Extracting ${BINUTILS_ARCHIVE}"
                tar -xzf ${BINUTILS_ARCHIVE}
        fi
}


BUILD_DIR_PREFIX=build-

#
# Builds Binutils.
#
do_binutils_build() {
        BUILD_DIR_BINUTILS=${BUILD_DIR_PREFIX}binutils-${TARGET_ARCH}

        # Remove dir if it exists.
        if [ -d $BUILD_DIR_BINUTILS ] ; then
                rm -rf $BUILD_DIR_BINUTILS
        fi

        echo "Building binutils..."

        # Changing directory, so use a sub-shell (?)
        (
                # Create a the build directory.
                mkdir ${BUILD_DIR_BINUTILS} && cd ${BUILD_DIR_BINUTILS};
                # Configure, build and install binutils
                ../${BINUTILS_VERSION}/configure ${BINUTILS_CONFIGURE_ARGS} &&
                ${GNU_MAKE} -j 12 -w all && ${GNU_MAKE} -w install
        )

        # Remove build dir
        rm -rf $BUILD_DIR_BINUTILS

        echo "Binutils Build done."
}

#
# "Builds" cygwin. Actually, it only copies some headers around.
#
do_cygwin_build() {
        HEADERS=${PREFIX}/${TARGET_ARCH}/sys-include

        mkdir -p $HEADERS  &&
        cp -rf ${CYGWIN_DIR}/newlib/libc/include/* $HEADERS &&
        cp -rf ${CYGWIN_DIR}/winsup/cygwin/include/* $HEADERS
}

#
# Builds GCC
#
do_gcc_build() {
        BUILD_DIR_GCC=${BUILD_DIR_PREFIX}gcc-${TARGET_ARCH}

        # Remove dir if it exists.
        if [ -d $BUILD_DIR_GCC ] ; then
                rm -rf $BUILD_DIR_GCC
        fi

        echo "Building GCC..."

        # Changing directory, so use a sub-shell (?)
        (
                # Create a the build directory.
                mkdir ${BUILD_DIR_GCC} && cd ${BUILD_DIR_GCC};
                # Configure, build and install GCC.
                ../${GCC_VERSION}/configure $GCC_CONFIGURE_ARGS &&
                ${GNU_MAKE} -j 12 -w all && ${GNU_MAKE} -w install
        )
        rm -rf $BUILD_DIR_BINUTILS

        echo "GCC Build done."
}

do_fetch
do_extract
do_binutils_build
do_cygwin_build
do_gcc_build

Unfortunately, the gcc binary built by the script, located in /opt/i386-tiano-pe/bin, can’t produce binaries. Invoking the compiler on a source file (“Hello, World!” program) dies with:

$ /opt/i386-tiano-pe/bin/gcc main.c -o main
/opt/lib/gcc/i386-tiano-pe/4.2.3/../../../../i386-tiano-pe/bin/ld: crt0.o: No such file: No such file or directory
collect2: ld returned 1 exit status

I assume this is because I skipped the last two steps in the list at the beginning of this post. However, using the compiler to generate an assembler file (parameter -S) and then running the assembler on that file to produce an object file does indeed produce a PE/COFF object file.

$ cd /opt/i386-tiano-pe/bin
$ ./gcc -S ~/main.c
$ ./as -o main.o main.s
$ file ./main.o
./main.o: MS Windows COFF Intel 80386 object file

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