Re: [Xen-devel] How to debug XEN, in case where DomU/Dom0 gets unresponsive?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I would like to know how to debug xen.
> To give some more informations, I would like to explain why I'd like to do
> this. 
> I've compiled xen from source (3.1.x/unstable) and installed it on Debain
> etch. Furthermore I've installed 2 DomU, one HVM (Win2k3) and one EFW
> (Endian Firewall, RH-based 2.6.9-55 kernel). 
> Both DomU's are running fine for about 15 minutes. But that differs from
> time to time. If something happens (like file transfer or http traffic)
> then all DomUs and the Dom0 get unresponsive. 
> I think the "hang" wouldn't be xen related, if only the DomUs would crash
> and the Dom0 would reachable. But with the described problem the Dom0 also
> gets unresponsive. Furthermore the DomUs weren't crashed, because the
> console of EFW/"xm top" details this. Anymore I can't see any logs at Dom0
> that the bridges went down. A restart of the Dom0 fixes the problem as it
> appears again the next time. 
> So, would there be any way to debug this, I think xen-related, problem?

Do you have any direct physical access to the machine?  Or maybe a remotely 
accessible serial line?  That would make fact-finding easier if (for 
instance) the dom0 network connection has died for some reason but the system 
is actually still up.

Otherwise, I guess you could check the Xend logs for anything suspicious and 
the system logs for any kernel oopses?

From my reading of the code for xenconsoled you should be able to 
run "xenconsoled -l hv" in order to get it to log messages that come out 
of "xm dmesg" into /var/log/xen/hypervisor.log which you could also inspect 
after any crash...  I can't find a more friendly way of activating that 
logging.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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