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Date: Fri, 9 Dec 2011 08:28:17 +0100
From: Ingo Molnar <mingo@elte.hu>
To: "Yu, Fenghua" <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, H Peter Anvin <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        linux-kernel <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH v4 0/7] x86: BSP or CPU0 online/offline
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* Yu, Fenghua <fenghua.yu@intel.com> wrote:

> > 
> > * Fenghua Yu <fenghua.yu@intel.com> wrote:
> > Then if demand for this picks up some more intelligent method of
> > cooperating with the firmware could be added: the firmware could
> > actually signal to us whether it supports suspend/resume from
> > other than the boot CPU.
> 
> We started to think how to handle the resume issue in 
> firmware, e.g. the way you talked, or change boot CPU to 
> another online CPU to execute resume procedure.
> 
> A firmware solution is a long run. Currently we don't 
> suspend/hibernate when BSP is offline. If a firmware solution 
> is available, we can change the sanity check to allow 
> suspend/hibernate if CPU0 is offline for new firmware. But 
> even when the solution is available in new firmware, we still 
> need to do the same sanity check on legacy firmware.

Right.

You convinced me, if there's no objections i guess we could try 
this feature carefully, if it's named in some more descriptive 
manner such as:

   x86: Arbitrary CPU hot(un)plug support

Nobody outside x86 devs knows 'BSP' means and why they should 
care.

The minor usability/testability/self-test improvements i 
suggested need to be added as well.

Thanks,

	Ingo