Re: ttyflags hangs on Dell PowerEdge R200

[Theo de Raadt]

I think the bug is that com_acpi_match() should call ic/com.c comprobe1(),
which verifies that an actual chip exists, rather than simply trusting the
ACPI tables.  If attach succeeds, open and ioctl become callable, and at
that point if real hardware isn't present, the driver reacts very poorly.