I just had my x86, 1.5N box panic at shutdown with the following trace:
	panic
	vgonel
	vflush
	ffs_flushfiles
	ffs_unmount
	dounmount
	vfs_unmountall
	vfs_shutdown
	cpu_reboot
	sys_reboot
	syscall_plain

I don't have the exact panic message on hand, but thought I'd ask if it
rang a bell to anyone and/or if it was a known case.  I do have the crash
dump if not, so I can extract out the important info if needed later.

Before the panic, I had rebuilt the 1.5N tree and at the same time built
some 1.5.1_ALPHA boot floppies.  I mention this in case it matters, since
the messages on the console before the panic were all of the "vnd0: no disk
label" variety (which I think is produced normally during the build, but I
built from X and didn't see them until the shutdown dropped me into the 
debugger...).

Let me know if I should file a PR with this or if it's known.

Thanks,
--rafal

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Rafal Boni                                                   rafal@mediaone.net