anchor.diff:  
     qemuCommandGeneric = ''
       PATH="${samba}/sbin:$PATH" \
  -    ${kvm}/bin/qemu-kvm \
  +    ${qemuProg} \
  +      -enable-kvm \
         -nographic -no-reboot \
         -smb $(pwd) -hda $diskImage \
         $QEMU_OPTS
  
positive.code:   # in parallel).  So apply a patch to increase the timeout to 120s.
    kernel = assert pkgs.linux.features.cifsTimeout; linuxKernel;
  
    kvm = pkgs.qemu_kvm;
  
  
    modulesClosure = makeModulesClosure {
  
negative.code: 
  
    qemuCommandLinux = ''
      ${qemuProg} \
        -enable-kvm \
        ${lib.optionalString (pkgs.stdenv.system == "x86_64-linux") "-cpu kvm64"} \
        -nographic -no-reboot \
        -net nic,model=virtio \
  