kern/122683: Accessing /dev/cuaa0 causes system to freeze

[vwe at FreeBSD.org]

Synopsis: Accessing /dev/cuaa0 causes system to freeze

State-Changed-From-To: feedback->open
State-Changed-By: vwe
State-Changed-When: Tue Apr 15 19:26:16 UTC 2008
State-Changed-Why: 

feedback received by private mail and posted to the audit trail.
The problem here is, the kernel is being instructed by /boot/device.hints
to enable the 1st serial device cuad0 (by default) but no hardware is being
found. The created character device /dev/cuad0 goes into nowhere and the
system is freezing on access.
It's easy to solve (by disabling hint.sio.0) in device.hints or attach it
to the ACPI bus but the default setting causes the system to freeze
while there's no COM port.
We'll see things like that in the near future as more systems are
being shipped w/o serial ports anymore.

http://www.freebsd.org/cgi/query-pr.cgi?pr=122683