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Re: [Xen-devel] Xen 4.0.4, kernel 3.5.0 HVM crash and kernel BUG

2012/10/3 Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>
On Wed, Oct 3, 2012 at 7:45 AM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
> On Wed, Oct 03, 2012 at 12:21:47PM +0300, Valtteri Kiviniemi wrote:
>>    Hi,
>>    I disabled NUMA and upgraded to Xen 4.2.0. Windows domU starts now fine
>>    and I cant anymore reproduce the hotplug problems. VNC output is still
>>    just black screen and it actually crashes the the whole VNC client when
>>    after a few seconds. RealVNC just shuts itself down and tightvnc crashes.
> Valtteri: Can you actually paste the names of the .config options you disabled
> and got the dom0 kernel working without crashes?
> Maybe Konrad can comment if the current upstream dom0 kernel is supposed to work
> with NUMA support enabled / compiled in?

There is a patch to actually disable it since we do not provide any
NUMA information
to the guest. And the dom0 has access to extra information (ACPI,
Northbridge, etc)
so it might think to create a NUMA topology and get it wrong.

But his dmesg did not have anything obvious related to NUMA, so  I am
perplexed that
turning that off would have made such a difference.

Valterri - if you just pass 'numa=off' on the Linux command line with
the old kernel
(the one that had the NUMA enabled) does that make it the iput issue go away?

You VNC issue .. does it work if you launch PV guests? Or is it only
for HVM guests?


Well it might be that disabling NUMA did not fix the problem since the crash is sometimes hard to reproduce. Sometimes it will crash everytime and sometimes I have to restart the domU 30 times before it causes that crash. But I have been testing this whole day and I have not been able to reproduce the crash anymore. I also upgraded from Xen 4.0.4 to Xen 4.2.0 so that combined for the NUMA disabling might have also affect, but I did also get the same crash on Xen 4.2.0 previously, so it probably does not affect. At the moment I cannot test enabling the NUMA since now when I got it working (at least it think that it works now) I want to figure out the VNC problem, since the VNC problem is very critical to me. I'm probably ordering another computer with the same hardware later this month and then I can use it as my primary test/dev server and try to test the NUMA again.

At the moment I dont have any PV guests that I could test the VNC with. But maybe I could try installing one. I also started a new thread about the VNC problem, so I think that we should continue the VNC discussion on that thread.

- Valtteri

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