PANIC! UNIX System Crash Dump Analysis Handbook (Bk/CD-ROM)

Can you get a core file?

Not usually. The catastrophic nature of this event means that even if you do see a boot PROM ok prompt, it's likely that the CPU registers have been corrupted already, and running a sync command will either fail or will give a core dump that is useless ”one that is unreadable, or has no good information left in it to examine. It is always worth a try, but there are some other things you should do first.