Modify nfs_diskless.c to recognize the environment variable boot.nfsroot.nfshandlelen and set the diskless root fs to use NFSv3 and this file handle length when it is set. If this environment variable is not set, the diskless root fs will use NFSv2 and the same defaults as before. This fixes the problem where the diskless nfs root fs had to be on a FreeBSD server for NFSv3 to work, because it did not know the correct file handle length and assumed the size used by FreeBSD. Until pxeboot and loader are replaced by ones built from commits coming soon, boot.nfsroot.nfshandlelen will not be set by them and the diskless root fs will use NFSv2 unless the /etc/fstab entry has the "nfsv3" option specified.
Modify nfs_diskless.c to recognize the environment variable
boot.nfsroot.nfshandlelen and set the diskless root fs to
use NFSv3 and this file handle length when it is set. If
this environment variable is not set, the diskless root fs
will use NFSv2 and the same defaults as before. This fixes
the problem where the diskless nfs root fs had to be on a
FreeBSD server for NFSv3 to work, because it did not know
the correct file handle length and assumed the size used
by FreeBSD. Until pxeboot and loader are replaced by ones
built from commits coming soon, boot.nfsroot.nfshandlelen
will not be set by them and the diskless root fs will use
NFSv2 unless the /etc/fstab entry has the "nfsv3" option
specified.

Tested by:	danny at cs.huji.ac.il
MFC after:	2 weeks

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase