There is a new release of lsof out which has a bug fix in it for Linux with sparc64 kernels. The previous version doesn't properly parse /proc/net/unix (which has some 64-bit quantities in it) and thus fails to map Unix-domain sockets to their names. Try running lsof on an Ultra and notice that the lines corresponding to Unix-domain sockets say: gnome-ter 2709 jsergent 8u sock 0,0 10656 can't identify protocol (for instance) lsof 4.43, which just came out, has a tiny fix from me in it that fixes this behavior, in dialects/linux/proc/dsock.c.
Upgrade (and your patch) is in lsof-4.43-1