Re: [PATCH v5 08/12] x86/smpboot.c: Wake up CPU0 via NMI instead of INITs

[Brian Gerst]

On Wed, Jan 11, 2012 at 12:04 PM, Fenghua Yu <fenghua.yu@xxxxxxxxx> wrote:
> From: Fenghua Yu <fenghua.yu@xxxxxxxxx>
>
> Instead of waiting for STARTUP after INITs, BSP will execute
> the BIOS boot-strap code which is not a desired behavior for
> waking up BSP. To avoid the boot-strap code, wake up CPU0 by
> NMI instead.
>
> This works to wake up soft offlined CPU0 only. If CPU0 is hard offlined (i.e.
> physically hot removed and then hot added), NMI won't wake it up. We'll change
> this code in the future to wake up hard offlined CPU0 if real platform and
> request are available.
>
> AP is still waken up as before by INIT, INIT, STARTUP sequence.

Would clearing IA32_APIC_BASE_MSR.BSP avoid calling the BIOS code when
the cpu is brought back online?  Setting that flag in another cpu that
is still online might also allow suspend/resume to work.

--
Brian Gerst
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