Xen devel - Apr 2008 - Random reboots with Xen 3.2.1

I am seeing random reboots after installing Xen 3.2.1 (running with
linux-2.6.18-8 pulled from a few days ago). So far, the reboots only
happen if I have enabled cpufreq=dom0-kernel and actually run
frequency scaling (such as with the ondemand governor). The reboots
only happen after a few hours. The machines seem to be stable if I
pass the cpufreq option to Xen but disable frequency scaling.

I can''t see anything in the log files that looks suspicious right
before the reboot. The worst I have seen are a couple of "Timer went
backwards" error messages but they don''t always show up in the
logs.
Anything else I should be poking at to figure out why this might be
happening and if there are any potential fixes?

Thanks,
Niraj

-- 
http://www.hpl.hp.com/personal/Niraj_Tolia/

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Hi,
>I am seeing random reboots after installing Xen 3.2.1 (running with
>linux-2.6.18-8 pulled from a few days ago). So far, the reboots only
>happen if I have enabled cpufreq=dom0-kernel and actually run
>frequency scaling (such as with the ondemand governor). The reboots
>only happen after a few hours. The machines seem to be stable if I
>pass the cpufreq option to Xen but disable frequency scaling.
>
>I can''t see anything in the log files that looks suspicious right
>before the reboot. The worst I have seen are a couple of "Timer went
>backwards" error messages but they don''t always show up in the
logs.
>Anything else I should be poking at to figure out why this might be
>happening and if there are any potential fixes?
>
You can see the panic log
if you add "noreboot" option to xen''s boot parameter.

Best Regards,

Akio Takebe


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Hi Akio,

I had tried noreboot earlier but it had not prevented the machine from
rebooting. Even after hooking the machine up a remote console, I would
not see anything being sent to screen. The machine would "hang" for a
few seconds and then reboot.

In case it helps someone else, I do believe that I have managed to
figure out the problem. Evidently the BIOS on this machine enabled the
processors to enter a low power halt state (AMD C1 Clock Ramping) and
this did not agree with Xen. Turning this feature off in the BIOS
seems to have made my problems go away.

Cheers,
Niraj

On Sun, Apr 27, 2008 at 8:48 AM, Akio Takebe <takebe_akio@jp.fujitsu.com>
wrote:
> Hi,
>
>
>
>  >I am seeing random reboots after installing Xen 3.2.1 (running with
>  >linux-2.6.18-8 pulled from a few days ago). So far, the reboots only
>  >happen if I have enabled cpufreq=dom0-kernel and actually run
>  >frequency scaling (such as with the ondemand governor). The reboots
>  >only happen after a few hours. The machines seem to be stable if I
>  >pass the cpufreq option to Xen but disable frequency scaling.
>  >
>  >I can''t see anything in the log files that looks suspicious
right
>  >before the reboot. The worst I have seen are a couple of "Timer
went
>  >backwards" error messages but they don''t always show up
in the logs.
>  >Anything else I should be poking at to figure out why this might be
>  >happening and if there are any potential fixes?
>  >
>  You can see the panic log
>  if you add "noreboot" option to xen''s boot parameter.
>
>  Best Regards,
>
>  Akio Takebe
>
>


-- 
http://www.hpl.hp.com/personal/Niraj_Tolia/

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