Here's some documentation of it for www/ I think there should also be some mention of this functionality in diskless(8), but I don't know where to put it, and I don't want to just .Xr it to boot_sparc64 because diskless is for all archs and none of the other boot_*s are referenced.
Index: sparc64.html =================================================================== RCS file: /cvs/www/sparc64.html,v retrieving revision 1.356 diff -u -p -r1.356 sparc64.html --- sparc64.html 1 Nov 2013 21:36:17 -0000 1.356 +++ sparc64.html 11 Feb 2014 01:06:40 -0000 @@ -721,7 +721,12 @@ as well as network and diskless installs the <tt>bsd.rd</tt> standalone miniroot over NFS. Refer to the <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=diskless&sektion=8";>diskless(8)</a> - manual page for details on how to setup a network boot environment. + manual page for details on how to setup a network boot environment in + general, and + <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=boot_sparc64&sektion=8&arch=sparc64";>boot_sparc64(8)</a> + for information about manually specifying network boot options on newer sparc64 + machines in such a way that does not require all the daemons described in + diskless(8). </ul> <p>
