[Skiboot] [RFC PATCH] opal/xstop: Use nvram param to enable/disable sw checkstop.

[ppaidipe]

On 2017-12-15 22:06, Mahesh Jagannath Salgaonkar wrote:
> On 12/15/2017 01:05 PM, ppaidipe wrote:
>> On 2017-12-15 06:34, Balbir Singh wrote:
>>> On Thu, 14 Dec 2017 22:45:48 +0530
>>> ppaidipe <ppaidipe at linux.vnet.ibm.com> wrote:
>>> 
>>>> Hi Mahesh
>>>> 
>>>> On 2017-12-14 21:06, Mahesh J Salgaonkar wrote:
>>>> > From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
>>>> >
>>>> > Add a mechanism to enable/disable sw checkstop by looking at nvram
>>>> > option
>>>> > opal-sw-xstop=<enable/disable>.
>>>> >
>>>> > For now this patch disables the sw checkstop trigger unless explicitly
>>>> > enabled through nvram option 'opal-sw-xstop=enable'. This will
>>>> allow an
>>>> > opportunity to get host kernel in panic path or xmon for unrecoverable
>>>> > HMIs or MCE, to be able to debug the issue effectively.
>>>> 
>>>> It will be good to enable by default, and let's give control to user 
>>>> to
>>>> disable
>>>> the sw-xstop using nvram option. Otherwise all test infrastructures 
>>>> will
>>>> break.
>>>> 
>>> 
>>> It's the otherway around right? Lets look at what happens today
>>> 
>>> 1. We get a software initiated checkstop on a WSP box
>>> 2. The BMC decides to reboot the box after a timeout
>>> 3. The BMC shows that a software initiated checkstop took place
>>> 
>>> How is this useful?
>> 
>> you are right it is of less useful in case of BMC systems, but still 
>> we
>> can stop
>> the auto reboot after checkstop and use existing pdbg tools to collect
>> require debug
>> data(Not sure how much useful it can capture).
>> 
>> 
>>> 
>>> On the FSP side, we should still log our diagnostic information
>>> before the OS reboots.
>>> 
>> 
>> Correct.
>> 
>>> Am I missing something?
>>> 
>> 
>> And it disables for all P8 platforms as well. So atleast we can enable
>> it there.
> 
> Hmm.. We can add p9 check and keep the p8 behaviour as is. Would that 
> help ?
> 

yes, that will be good.

> Thanks,
> -Mahesh.
> 
>> 
>>> Balbir Singh.