Kernel Build Knob for kgssapi_krb5?

Is there a knob somewhere to enable building of the kgssapi_krb5 module?

I have just built 8.0-RC2/i386 and decided to have a look at the
(experimental) NFSv4 stuff.  I included options NFSD and NFSCL in my
kernel configuration.  nfsd(8) indicates that gssd(8) has to be running
in order for the server to provide gss/krb5 access control.  If I try
starting gssd(8) it complains of a missing kgssapi_krb5 kernel module.
The module hasn't been built.  I've checked the GENERIC and NOTES files
and can't find any reference to kgssapi_krb5.  Is there an undocumented
configuration option for this?

Also, is there a "getting started" or "how to test" page somewhere to
give us some clues to get this going?

Thank you.

-- 
John Marshall