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Re: [Xen-users] powerdown problem on XEN

Hi Ian,
many thanks for your suggestions and for helping out in trying to get to the roots of this issue. Sorry for my delay in responding - setting up a serial console took a bit of time, but please see my inline comments below.


Am 07.08.13 10:39, schrieb Ian Campbell:
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

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

None of the options listed in your link (reboot=b|t|k|n|w|c) managed to turn off power to the system. All but reboot=n (and also noreboot=true) did a reboot after requesting a powerdown with shutdown -h now. reboot=n or noreboot=true just left the machine's power on with the last message on the console (from the gentoo dom0 shutdown) reading
[ <no secs since start> ] Power Down.

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.

I have set up a serial console and the output is attached to this mail. It did however not contain the message you expected, but that might be due to the fact that I did not request a reboot but rather a powerdown. At least that's my guess.

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.
This was my initial try, but I did not manage to get that working. I guess, now having the serial console log available, might render this useless anyways for my case ...

I hope the attached file helps in narrowing the powerdown problem down. If you require any more informatio, I'd be more than happy to provide that.

Many thanks again ...


Attachment: XEN console
Description: Text document

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