Re: OT: xen libvirt issue

[Jim Fehlig <jfehlig@suse.com>]

AL13N wrote:
> Op maandag 8 april 2013 06:22:49 schreef Marek Marczykowski:
>   
>> On 05.04.2013 13:13, George Dunlap wrote:
>>     
>>> On Fri, Apr 5, 2013 at 9:21 AM, Dario Faggioli
>>>
>>> <dario.faggioli@citrix.com> wrote:
>>>       
>>>> On gio, 2013-04-04 at 21:49 +0200, AL13N wrote:
>>>>         
>>>>> i realise this is completely off-topic, but if someone on this list has
>>>>> some knowledge on this, see:
>>>>>
>>>>> https://www.redhat.com/archives/libvir-list/2013-April/msg00189.html
>>>>>
>>>>> the issue is that shutting down xen domains, segfaults libvirtd... which
>>>>> is
>>>>> annoying
>>>>>           
>>>> I don't have any clue on this... But, perhaps, Jim does (Cc-ing him)?
>>>>         
>>> The e-mail that AL13N linked to was actually from Jim, saying he would
>>> be really busy for a while and unable to look at it.
>>>
>>> The question isn't off-topic, as libxl and xend have to work closely
>>> with libvirt.  Unfortunately, I don't think any of the active
>>> developers on this list has much familiarity with libvirt.  It Would
>>> Be Good if someone could step up and learn, but with our feature
>>> freeze next week, we're also kind of heads-down getting stuff
>>> implemented...
>>>       
>> I believe it is already fixed in unstable by this commit:
>> 5f5ef65babc2ca15f43b775c4b47b0102fa2a632 "libxl: fix stale timeout event
>> callback race"
>>
>> Sadly backport to 4.2 isn't trivial.
>>     
>
> Looking at the patch i totally agree that it isn't trivial...
>   

It will certainly help, but I've heard reports there are still problems
even with that patch.  IIRC, Bamvor has seen a similar segfault using
git master of libvirt and xen-unstable, although it is a bit harder to
trigger.

I think we need to rework the code for handling shutdown events.  The
current code worked with libxl in Xen 4.1, but has proven to be racy
with libxl in Xen 4.2.  I plan to work on this, but unfortunately not
for a few weeks.  I'm busy with another project this week and will be
traveling the week of April 15.

> i'll hold off for now. and will work more towards libvirt integration for 
> Mageia 4 (our release freeze is now in effect for Mageia 3).
>   

FYI, although it is deprecated, the xm/xend toolstack works well with
Xen 4.2, and the legacy libvirt xen driver is quite stable.  It was the
first hypervisor driver in libvirt  :).

Regards,
Jim