reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/commit/?id=24c34dab5ea410773423ea23f86eeb054e4d37a9
        git remote add jpoimboe https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git
        git fetch --no-tags jpoimboe asm-call-constraint-fix
        git checkout 24c34dab5ea410773423ea23f86eeb054e4d37a9
        # 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/