Re: [Xen-users] powerdown problem on XEN

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-07-29 at 00:03 +0200, Atom2 wrote:
> Hi guys,
> I have a problem with powering down my system under the XEN hypervisor. 
> System details are as follows:
> 
> gentoo linux, X86_64
> XEN version 4.2.2
> linux hardened kernel 3.9.5 as dom0
> Xeon E3 1260L processor (vt-d capable)
> 32GB ECC RAM which has been thoroughly tested - so should be o.k.
> 
> when I issue "shutdown -h now" from dom0 the system usually reboots 
> instead of turning off power to the machine. There's the odd occassion 
> (probably 1 in every 10 to 20 shutdown attempts) when the system power 
> is actually turned off. There seems to be no rule to follow when this 
> happens.
> 
> If I use the exact same kernel and start w/o the XEN hypervisor 
> powerdown *always* works as expected when I use "shutdown -h now". So on 
> the face of it, this seems to point to the XEN hypervisor as the culprit.
> 
> Any idea/help on how to track down and solve the issue would be very 
> much appreciated. If you require any more information / log data, I'm 
> more than happy to provide that.

You could try the Xen reboot= option, which controls which hardware
mechanism tries to use to reboot. See
http://xenbits.xen.org/docs/unstable/misc/xen-command-line.html for
details. 

> Unfortuantely however, there seems to be no log / dmesg data available 
> during shutdown as syslog-ng is stopped. The only thing I can confirm 
> that there's no strange output on the console during either bootup or 
> shutdown: All services / daemons start up o.k. and also during shutdown 
> all services seem to come to a proper halt. The root filesystem is 
> re-mounted r/o and the last message reads "Power down" - only to then 
> reboot the system by going through a BIOS power-on sequence.

I would expect you to see a message to the affect "dom0 has shutdown,
rebooting" from the hypervisor at the very end. You may need a serial
console to see this though I suppose.
http://wiki.xen.org/wiki/Xen_Serial_Console

In fact if the reboot= options don't help then setting up a serial
console to get at Xen's logs during reboot is probably the next step.

Alternatively I think "console=vga vga=current,keep" will keep the VGA
for Xen so you can see what is happening, but at the expense of no VGA
for dom0 (I've never actually tried this myself, but I think it should
work). This might be OK if you can use ssh to initiate the reboot and
then taker a photo of the resulting Xen logs.

Ian.


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