reproduce (this is a W=1 build):
        # https://github.com/kvm-x86/linux/commit/ca1831d6ffa3a240830014a0c96633aed6d07367
        git remote add kvm-x86 https://github.com/kvm-x86/linux
        git fetch --no-tags kvm-x86 exports
        git checkout ca1831d6ffa3a240830014a0c96633aed6d07367
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kvm/