Re: [Xen-devel] [Xen-users] Xen 4.3.1 / Linux 3.12 panic

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.11.13 at 12:20, Wouter de Geus <benv-xensource.com@xxxxxxxxxxxxx> 
>>> wrote:
> The BIOS has the following options that I consider relevant:
>   Name         [Current] (Options)
> - PowerNow     [Enabled]
> - C State Mode [C6] (Disabled, C6)
> - PowerCap     [P-state 0] (P-state 0 through 4)
> - HPC Mode     [Enabled] (Disabled, Enabled)
> - CPB Mode     [Auto] (Disabled, Auto)
> - C1E Support  [Enabled] (Enabled, Disabled)
> 
> When I set PowerNow to disabled the C State Mode, PowerCap and HPC options 
> also disappear.
> After booting with PowerNow disabled (without the cpufreq option) I tried a 
> kernel compile
> twice and some heavy I/O under which the system was stable.
> So that seems to have the same effect as cpufreq=none.
> 
> - With PowerNow enabled (C State Mode and HPC / CPB Mode disabled ,no cpufreq 
> cmdline)
> the system also seems stable.
> - C State Mode set to C6 (HPC/CPB disabled, no cpufreq cmdline), seems 
> stable.
> - HPC enabled, (CPB disabled, no cpufreq cmdline), crashed (serial console 
> log attached
> as xen-crash-hpc-enabled).

Now we'd need to know what HPC actually means (it means nothing
to me in this context) - I'd have expected the PowerCap (as referring
to P-states) to be the interesting one.

In any event - with cpufreq=dom0 and no cpufreq drivers loaded
in dom0 (which as Konrad says should be the default), there
shouldn't be any P-state management.

But you being able tom suppress the problem with cpufreq=none
also suggests that quite likely there's either a problem with the
silicon, or the PowerNow driver in Xen went sufficiently much out
of date wrt newer CPUs that it's not usable anymore (it certainly
hasn't been touched in meaningful ways for quite a while). You
may have said so before, but can you confirm that under native
Linux with acpi-cpufreq (or the powernow driver) loaded, you
don't have this kind of problem? If so, could you please provide
contents of the respective sysfs nodes?

Jan


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