To port p3nfsd to another architecture, take a look at:

mp_serial.c for the serial drives setting
mp_mount.c  for the nfs mount (The amd source could help you)
config.h    for the defaults


Content of the files:
mp.h:        Various defines
mp_inode.c:  the inode routines and the read/write cache routines.
mp_main.c
mp_mount.c:  nfs mount & rpc service start
mp_pfs_ops.c:the nfs routines
mp_serial.c: tty settings
mp_xmit.c    description of protocol used between the psion and the
             workstation, receive & send routines
nfs_*:       all generated from nfs_prot.h via rpcgen, with nfs_prot_svc.c
             slightly modified
nfsc.opl     the opl program for the psion
