Re: [RFC][PATCH v2 2/3] Hold multiple logs

[Don Zickus]

On Fri, Jul 20, 2012 at 12:39:24AM +0000, Seiji Aguchi wrote:
> 
> Thank you for describing this in detail.
> 
> > Yes - if the OOPs is instrumental in the path leading to the hang/panic - then the OOPS is the first place to look for the root cause of
> > the problem. But it will be a case by case analysis.
> > Sometimes the OOPS might be unconnected. If possible we'd like to log more information to allow detective work to decide whether
> > there is a connection. But as I mentioned above there are severe limits to how much better things are by storing more information.
> 
> I understand the reason why you think 3 or 4 logs are reasonable.
> There are some cases  2nd or 3rd oops is critical....
> 
> I have some enterprise customers who are sensitive for a software failure  and specify panic_on_oops=1.
> In this case, they don't need 3,4 logs. 2 logs  are enough.
> 
> So, kernel parameter should be as follows.
> 
> Log_num =1
>   - For users who want to hold just one log.
> 
> Log_num=2
>   - For users who can handle multiple logs and 1st oops is concerned. (by specifying panic_on_oops=1)
> 
> Log_num=3,4
>  -  for users who care about 2nd or 3rd oops.
> 
> Log_num=5 or more
> Invalid value.

What is the harm of not using this and just letting the number be infinite
(or until EFI runs out of space)?  Is it a big deal if extra failures are
logged?

The hope would be a daemon would clear the old logs out and you never run
out of space.

Cheers,
Don
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