Connecting to serial port

Ted Mittelstaedt tedm at
Sat Feb 11 00:51:15 PST 2006

That happens, you can try a BIOS update, and also make sure
your motherboard CMOS settings specify the port for serial0,
and match port 0x3f8-0x3ff irq 4, and aren't set to auto.  You
can also try changing the setting for plug-and-play OS to off,
(or on, if it was off before)

You can ignore the message:

"configured irq 4 not in bitmap of probed irqs 0"

as long as your serial port actually responds.  A lot of motherboards
will emit this message but the serial port still works.  Unfortunately
it looks like yours isn't one of these due to the "not responding" error

Worst case, disble the motherboard serial ports and buy a pci serial
port card.

This seems to happen a lot on systems that use pci-express, probably
because they are tying the serial port hardware to the pci bus
rather than the isa bus.


>-----Original Message-----
>From: owner-freebsd-questions at
>[mailto:owner-freebsd-questions at]On Behalf Of Steve Douville
>Sent: Friday, February 10, 2006 9:25 PM
>To: freebsd-questions at
>Subject: Connecting to serial port
>I'm trying to connect to the serial port of a Dell PowerConnect 
>3024.  I've connected a null modem cable between them. During 
>boot, this is what is happening:
>Feb 11 00:34:17 server2 kernel: sio0: configured irq 4 not in 
>bitmap of probed irqs 0
>Feb 11 00:34:17 server2 kernel: sio0: port may not be enabled
>Feb 11 00:34:17 server2 kernel: sio0: <16550A-compatible COM 
>port> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
>Feb 11 00:34:17 server2 kernel: sio0: type 8250 or not responding
>Can anyone shed some light on what I might have done wrong or 
>where to continue looking? 
>freebsd-questions at mailing list
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