GuruCoding.com

Now it's time to replace second bootstrapping compiler with full-featured compiler tied to glibc and capable of building hosted code, not only freestanding code. Also new compiler will be independent from cygwin1.dll, unlike the old one.

1. Update C:\MinGW\msys\1.0\opt\crosstool\src\build_cross_toolchain.sh as follows:

   #!/bin/bash
   export PATH=.:/usr/local/bin:/mingw/bin:/bin
   export PATH=$PATH:/c/WINDOWS/system32:/c/WINDOWS
   export PATH=$PATH:/c/WINDOWS/System32/Wbem
   export TARGET=arm-linux-gnueabihf
   export PREFIX=/opt/crosstool/gcc-8.3.0-glibc-2.28/$TARGET
   
   cd /opt/crosstool/src/build-binutils
   find . -delete
   LDFLAGS="-Wl,-s -Wl,-static -static -static-libgcc" \
     ../binutils-2.31.1/configure --target=$TARGET \
       --prefix=$PREFIX --with-sysroot=$TARGET \
       --disable-nls --with-arch=armv6
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to configure binutils ==="
       exit 1
   fi
   make all
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to make binutils ==="
       exit 1
   fi
   make install
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to install binutils ==="
       exit 1
   fi
   
   export PATH=$PATH:$PREFIX/bin
   cd /opt/crosstool/src/build-gcc
   find . -delete
   LDFLAGS="-Wl,-s -Wl,-static -static -static-libgcc" \
     ../gcc-8.3.0/configure --target=$TARGET --prefix=$PREFIX \
        --with-sysroot=$PREFIX --with-arch=armv6 --with-fpu=vfp --with-float=hard \
        --disable-sjlj-exceptions --enable-checking=release \
        --enable-linker-build-id --enable-gnu-unique-object \
        --disable-nls --enable-languages=c,c++ \
        --with-headers --enable-shared --enable-threads=posix \
        --disable-multilib -enable-__cxa_atexit \
        --disable-fixed-point \
        --disable-libmudflap --disable-libssp \
        --disable-libgomp --without-ppl --without-cloog \
        --with-gmp=/usr/local --with-mpfr=/usr/local \
        --with-mpc=/usr/local
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to configure gcc ==="
       exit 1
   fi
   make
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to make gcc ==="
       exit 1
   fi
   make install
   if [ "$?" -ne "0" ]; then
       echo "=== build script: failed to install gcc ==="
       exit 1
   fi
   
   echo "=== build script: OK ==="
   

2. Run C:\MinGW\msys\1.0\opt\crosstool\src\build_cross_toolchain.cmd and wait until it completes.
3. If there are no errors, shutdown the MinGW VM and make snapshot "SNAP-D".

Notes:

• Multilib is a special feature of GCC to allow building 32-bit targets on x86_64 platform. It's useless on ARM.
• LDFLAGS="-Wl,-s -Wl,-static -static -static-libgcc" option prevents dynamic linking to libgcc_s_dw2-1.dll (runtime library of MinGW) and also automatically strips EXE files at build time.

Additional steps to support SoftFP ABI:

1. Replace TARGET=arm-linux-gnueabihf with TARGET=arm-linux-gnueabi in build_cross_toolchain.sh
2. binutils configure flags: --with-arch=armv4t
3. gcc configure flags: --with-arch=armv4t --with-float=soft. Also remove --with-fpu=vfp.
4. Run C:\MinGW\msys\1.0\opt\crosstool\src\build_cross_toolchain.cmd and wait until it completes.
5. If there are no errors, shutdown the MinGW VM and make snapshot "SNAP-E".

>> Read next section or buy already prepared cross-compiler (€10) to save your time.