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Date: Thu, 8 Mar 2012 12:20:15 -0600
From: Scott Wood <scottwood@freescale.com>
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To: McClintock Matthew-B29882 <B29882@freescale.com>
Subject: Re: [PATCH] PPC: Don't sync timebase when inside VM
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Cc: "<kvm-ppc@vger.kernel.org>" <kvm-ppc@vger.kernel.org>,
 Wood Scott-B07421 <B07421@freescale.com>,
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On 03/08/2012 11:31 AM, McClintock Matthew-B29882 wrote:
> On Fri, Mar 2, 2012 at 11:17 AM, Scott Wood <scottwood@freescale.com> wrote:
>> On 03/02/2012 10:30 AM, Alexander Graf wrote:
>>>
>>> On 02.03.2012, at 17:20, Scott Wood wrote:
>>>> Again, for 85xx we should *never* sync the timebase in the kernel,
>>>> hypervisor or no.
>>>
>>> The code says "if the kexec config option is enabled, do the sync". I'm fairly sure it's there for a reason.
>>
>> Sigh.  I forgot about that.  It's because instead of doing kexec the
>> simple way, we actually physically reset the core.  We really shouldn't
>> do that.  And we *really* shouldn't do it just because CONFIG_KEXEC is
>> defined, regardless of whether we're actually booting from kexec.
> 
> How would one rocver a core that's off in the weeds? 

System reset?

I thought kexec was for upgrading your kernel, not recovering from crashes.

> We need to at least stop it somehow before we restart into the kdump kernel. kexec
> seems feasible since we have all the cores in a known state...

Stop, yes.  Reset, no.

-Scott