From: "J. Bruce Fields" <bfields@fieldses.org>

The kernel currently prints:

 nfsd: nobody listening for auth.unix.ip upcall; has some daemon not been started?

on every bootup, during initscripts.

Neil Brown <neilb@cse.unsw.edu.au> says:

  It was part of the recent set of idmapper patches.  Bruce wanted the admin
  to get a warning when the idmapper daemon wasn't running.  I thought the
  same warning should apply to any daemon that responded to upcalls.

  In the case of auth.unix.ip it isn't strictly necessary for a daemon to be
  running (for comparability with 2.4).

  You can get rid of the warning by doing:

    mount -t nfsd nfsd /proc/fs/nfs

  before mountd is started (init scripts should start doing this I hope, but
  distributions don't tend to use the init script from nfs-utils, so it is
  hard to push it).  This will trigger mountd to listen on auth.unix.ip and
  others.


That's a hassle, so Bruce's patch limits the warning purely to the new
idmapper cache.  It provides a callback in the cache_detail that individual
caches can use to log messages when upcalls fail because a userspace daemon
not running.  Implement this method for the idmapping caches.