Re: [PATCH v4 0/7] x86: BSP or CPU0 online/offline

[Ingo Molnar <mingo@elte.hu>]

* Borislav Petkov <bp@amd64.org> wrote:

> On Tue, Dec 06, 2011 at 04:55:02PM +0530, Srivatsa S. Bhat wrote:
>
> > By the way, this problem is not tied to CPU0 alone, it 
> > exists for any CPU! (as long as we are talking about 
> > plugging in/out CPUs physically).
> 
> Just a reminder: before you guys go and wander off into the 
> woods of hypothetical with this, please make sure this use 
> case is relevant enough for the trouble. The only real reason 
> given so far AFAICT was RAS and to be able to offline BSP in 
> order to prolong system life before maintenance.
> 
> When you take it down for maintenance eventually, you don't 
> need to suspend but simply poweroff.

I think it's definitely a marginal and speculative feature - but 
the patches don't look overly complicated, so i'm not 
*completely* against removing various boot-CPU assumptions 
(although i'm predisposed against it) - if it is correct and if 
there's someone interested in doing proper patches.

All in one, the quality threshold for inclusion is very high but 
not an infinite number.

The specific point i tried to make about s2ram is to make sure 
it does not break during normal usage: for example someone 
offlines the boot CPU, but the box then gets suspended - that 
should not hang or crash.

Thanks,

	Ingo