I've got a hung v20z and I want to get a core. Luckily I had it configured to drop down to kmdb and I had a chatline available to people in my group. :-<
The trick is get the LOM to work with you. In this case, CTRL-e c l 0 (that is an 'L' and not a '1') got the LOM console to force the system to drop down into kmdb. And from there, it was easy to generate the core:
Jul 29 12:35:41 pnfs-17-22 last message repeated 1 time [halt aborted] [ignored] [halt sent] Welcome to kmdb kmdb: unable to determine terminal type: assuming `vt100' Loaded modules: [ scsi_vhci crypto mac cpc uppc neti sd ptm ufs unix cpu_ms.AuthenticAMD.15 sv mpt zfs krtld s1394 sppp rdc nca uhci ii hook lofs genunix idm ip nsctl logindmux nsmb sdbc usba specfs pcplusmp nfs md random cpu.generic sctp arp stmf sockfs smbsrv ] [1]> $Now I need to figure out why the system was wedged!
And the core was corrupt!