reproduce (this is a W=1 build):
        # https://github.com/kvm-x86/linux/commit/37f5146b36c9744a3011a889cdd71e4155d68dba
        git remote add kvm-x86 https://github.com/kvm-x86/linux
        git fetch --no-tags kvm-x86 svm
        git checkout 37f5146b36c9744a3011a889cdd71e4155d68dba

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/