anchor.diff:        source = "/run/${dirName}/nix-helpers/qemu-bridge-helper";
       };
   
  -    systemd.packages = [ pkgs.libvirt ];
  +    systemd.packages = [ cfg.package ];
   
       systemd.services.libvirtd-config = {
         description = "Libvirt Virtual Machine Management Daemon - configuration";
         script = ''
           # Copy default libvirt network config .xml files to /var/lib
           # Files modified by the user will not be overwritten
  -        for i in $(cd ${pkgs.libvirt}/var/lib && echo \
  +        for i in $(cd ${cfg.package}/var/lib && echo \
               libvirt/qemu/networks/*.xml libvirt/qemu/networks/autostart/*.xml \
               libvirt/nwfilter/*.xml );
           do
               mkdir -p /var/lib/$(dirname $i) -m 755
  -            cp -npd ${pkgs.libvirt}/var/lib/$i /var/lib/$i
  +            cp -npd ${cfg.package}/var/lib/$i /var/lib/$i
           done
   
           # Copy generated qemu config to libvirt directory
           cp -f ${qemuConfigFile} /var/lib/${dirName}/qemu.conf
   
           # stable (not GC'able as in /nix/store) paths for using in <emulator> section of xml configs
  -        for emulator in ${pkgs.libvirt}/libexec/libvirt_lxc ${cfg.qemuPackage}/bin/qemu-kvm ${cfg.qemuPackage}/bin/qemu-system-*; do
  +        for emulator in ${cfg.package}/libexec/libvirt_lxc ${cfg.qemuPackage}/bin/qemu-kvm ${cfg.qemuPackage}/bin/qemu-system-*; do
             ln -s --force "$emulator" /run/${dirName}/nix-emulators/
           done
   
  
positive.code: 
      systemd.services.virtlogd = {
        description = "Virtual machine log manager";
        serviceConfig.ExecStart = "@${pkgs.libvirt}/sbin/virtlogd virtlogd";
        restartIfChanged = false;
      };
  
  
negative.code:       # this file is expected in /etc/qemu and not sysconfdir (/var/lib)
        etc."qemu/bridge.conf".text = lib.concatMapStringsSep "\n" (e:
          "allow ${e}") cfg.allowedBridges;
        systemPackages = with pkgs; [ libressl.nc iptables cfg.package cfg.qemuPackage ];
        etc.ethertypes.source = "${pkgs.iptables}/etc/ethertypes";
      };
  
  