Pkg xen devel - Jun 2014 - how to get debugging output from dom0 kernel

Hi,

how could I get better debugging output from the dom0 kernel?

The kernel crashes after some time and debugging output to the console
is being scrolled off by messages about NMI stuff trying to do
something.

I'm using Debian stable and would like to make a bug report, but without
any useful information there's no point.

So far, all I can say is that it seems to take over 12 and less than 24
hours before the kernel crashes, and the one time I could see the
debugging output, it seemed to be related to the xen_blkback module
which might not like the aacraid module.  It has crashed three times so
far.  This goes along with having created a second logical volume on the
raid controller (still undergoing auto-sync) which has two LVM volumes
on it in a LVM volume group.  One of the LVM volumes is made available
to a domU:


disk = ['phy:/dev/vg_guests/lv_jupiter,xvda,w',
'phy:/dev/vg_mydata/lv_DATA,xvdb,w']


It didn't crash before adding the second volume.  I can't have this
server crashing all the time --- what can I do?

Is there a more recent kernel which might work better?


-- 
Knowledge is volatile and fluid.  Software is power.

On Sun, 2014-06-15 at 11:03 +0200, lee wrote:
> Hi,
> 
> how could I get better debugging output from the dom0 kernel?
Either configure a serial console [0] or add "noreboot" to your
*hypervisor* command line, so you can see (and perhaps
transcribe/photograph) the crash before manually rebooting.

[0] http://wiki.xen.org/wiki/Xen_Serial_Console

Ian.

Ian Campbell <ijc at hellion.org.uk> writes:
> On Sun, 2014-06-15 at 11:03 +0200, lee wrote:
>> Hi,
>> 
>> how could I get better debugging output from the dom0 kernel?
>
> Either configure a serial console [0] or add "noreboot" to your
> *hypervisor* command line, so you can see (and perhaps
> transcribe/photograph) the crash before manually rebooting.
The server isn't rebooting automatically, it only gets stuck.  I still
have a monitor connected to it, so I can see what's printed to the
console.  But the output is scrolled off screen by subsequent messages
so that it's gone by the time I notice that it hangs.

If there was a way to disable the subsequent messages, I could take a
picture.  Perhaps I can get output from a serial console if I manage to
set that up ... or maybe I can actually make it crash instead of having
to wait ...

>
> [0] http://wiki.xen.org/wiki/Xen_Serial_Console
>
> Ian.
>
>
>
>
-- 
Knowledge is volatile and fluid.  Software is power.