remote debug over usb vs. old serial cable?

[Ronald Klop]

On Thu, 26 Mar 2009 15:22:36 +0100, Andriy Gapon <avg at icyb.net.ua> wrote:

> on 26/03/2009 15:06 Erik Trulsson said the following:
>> On Thu, Mar 26, 2009 at 01:56:13PM +0100, Ronald Klop wrote:
>>> Hello,
>>>
>>> In the past I could catch a panic during boot via a serial cable  
>>> connected
>>> to another computer.
>>> My new computer only has USB-ports and ethernet. What kind of cable do  
>>> I
>>> need now to do remote debugging?
>>> The old computer also has usb, so I think the connection should be in  
>>> that
>>> corner.
>>> They all run 7-STABLE.
>>
>> USB won't work for that purpose.  It requires far too much kernel  
>> support to
>> be useful after a panic.
>
> Erik,
> in fact, there is a special USB (EHCI) mode for such purposes:
> http://www.coreboot.org/EHCI_Debug_Port
>
> But that requires some special HW in addition to SW support which our  
> doesn't have.
>
> BTW, Ronald, it is possible that you might have a serial header on  
> motherboard
> which is not connected to any traditional port.

Is that this sio0 one?
sio0: configured irq 4 not in bitmap of probed irqs 0
sio0: port may not be enabled
sio0: configured irq 4 not in bitmap of probed irqs 0
sio0: port may not be enabled
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 8250 or not responding
sio0: [FILTER]
sio1: configured irq 3 not in bitmap of probed irqs 0
sio1: port may not be enabled

I am going to open my computer tonight to see what is in there.

Ronald.