Re: Serial console - how to reboot?

On Sat, 12 Jun 2004, Eirik Oeverby wrote:

> I have recently been getting the following messages on my console:
> swap_pager: indefinite wait buffer: device: #amrd/0x20001, blkno: 1072,
> size: 4096
> swap_pager: indefinite wait buffer: device: #amrd/0x20001, blkno: 832,
> size: 4096
> swap_pager: indefinite wait buffer: device: #amrd/0x20001, blkno: 512,
> size: 4096
> swap_pager: indefinite wait buffer: device: #amrd/0x20001, blkno: 576,
> size: 4096
> swap_pager: indefinite wait buffer: device: #amrd/0x20001, blkno: 584,
> size: 4096
>
> I am aware that this usually indicates a bad drive or something, but
> given that it's a RAID volume hanging on an AMI MegaRAID controller
> (SCSI), and none of the drives in the array are degraded, that can't
> really be the case. I'm suspecting a bug in the driver (though freebsd
> 4.10 should be stable, right?) or a faulty cable or such.

Yes, usually it means the device is not responding to requests.  What kind
of container is your swap in? Mirror? Stripe?

> What would mitigate the problem for now though would be to have a way to
> reboot the system. I'm about 1000 miles away from the box, so I can't go
> there, but I do have access via serial console (which is where I'm
> getting these messages).

[...]

> Entering the kernel debugger might help, though I'm actually not sure if
> it's compiled into the running kernel. But if it is, how can I get to it
> via serial?

If you built the kernel with 'options BREAK_TO_DEBUGGER', then a serial
break will drop to ddb. From there you could do 'call boot(0)' to attempt
and orderly shutdown, or 'reset' to, well, reset :) There's also an
'ALT_BREAK_TO_DEBUGGER' option that emulates the sun alt-break -- [cr] ~
^B.

Without either of those, though, maybe you should call someone nearby and
entice them to press some buttons for you :)

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite_at_gumbysoft.com          |  www.FreeBSD.org