anchor.diff:    rpc.mountd, rpc.nfsd
     rpc.statd, rpc.lockd (if necessary), and
     rpc.rquotad"
  -
  -  I tried to mimic that with upstart, playing with stopping/stopped/started/starting
  -  events.
  -
  -  I consider two scenarios:
  -    - Starting at boot. Then, portmap will emit a started event.
  -    - "restart nfs-kernel-exports". Then, portmap will not emit anything. Due
  -      to the comment in postStart, this will happen on nixos-rebuild if
  -      the exportfs file changed.
  -
  -  From these scenarios, I came up with the startOn and stopOn at the time of commiting
  -  this comment.
   */
   
   
  
positive.code:   config =
    mkAssert
      (cfg.client.enable || cfg.server.enable -> config.services.portmap.enable) "
      Please enable portmap (services.portmap.enable) to use nfs-kernel.
    " {
  
      services.portmap.enable = mkAlways (cfg.client.enable || cfg.server.enable);
  
negative.code: 
      jobs =
        optionalAttrs cfg.server.enable
          { nfsd =
            { description = "Kernel NFS server";
  
              startOn = "started portmap";
              stopOn = "stopped statd or stopping portmap";
  
              preStart =
                ''
  