Re: [patch] add kdump_after_notifier

Jay Lan
2007-08-21T13:14:23Z

Vivek Goyal wrote:
> On Thu, Aug 16, 2007 at 06:26:35PM +0900, Takenori Nagano wrote:
>> Vivek Goyal wrote:
>> > So for the time being I think we can put RAS tools on die notifier list
>>> and if it runs into issues we can always think of creating a separate list.
>>>
>>> Few things come to mind.
>>>
>>> - Why there is a separate panic_notifier_list? Can't it be merged with
>>> die_chain? die_val already got one of the event type as PANIC. If there
>>> are no specific reasons then we should merge the two lists. Registering
>>> RAS tools on a single list is easier.
>> I think it is difficult, because die_chain is defined by each architecture.
>>
>
> I think die_chain is arch independent definition (kernel/die_notifier.c)?
> But anyway, to begin with it can be done only for panic_notifier.
>
>>> - Modify Kdump to register on die_chain list.
>>> - Modify Kdb to register on die_chain list.
>>> - Export all the registered members of die_chain through sysfs along with
>>> their priorities. Priorities should be modifiable. Most likely one
>>> shall have to introduce additional field in struct notifier_block. This
>>> field will be a string as an identifier of the user registerd. e.g
>>> "Kdump", "Kdb" etc.
>>>
>>> Now user will be able to view all the die_chain users through sysfs and
>>> be able to modify the order in which these should run by modifying their
>>> priority. Hence all the RAS tools can co-exist.
>> This is my image of your proposal.
>>
>> - Print current order
>>
>> # cat /sys/class/misc/debug/panic_notifier_list
>> priority name
>> 1 IPMI
>> 2 watchdog
>> 3 Kdb
>> 4 Kdump
>>
>
> I think Bernhard's suggestion looks better here. I noticed that
> /sys/kernel/debug is already present. So how about following.
>
> /sys/kernel/debug/kdump/priority
> /sys/kernel/debug/kdb/priority
> /sys/kernel/debug/IPMI/priority

Why separate priority files is better than a central file?
At least i think you get a grand picture of priority being
defined for all parties with a central file?

What do we decide priority if more than one component has
the same priority value?

Thanks,
- jay

>
> I think at some point of time we shall have to create another file say
> description.
>
> /sys/kernel/debug/IPMI/description
>
> Which can tell what does this tool do? Other a user might not have any
> clue how to prioritize various things.
>
> Thanks
> Vivek
>