linux-kernel - Re: [tip:x86/debug] x86, reboot: Use NMI instead of REBOOT

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Date:	Wed, 21 Dec 2011 10:24:53 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Don Zickus <dzickus@...hat.com>
Cc:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	andi@...stfloor.org, torvalds@...ux-foundation.org,
	peterz@...radead.org, robert.richter@....com, tglx@...utronix.de,
	mingo@...e.hu, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/debug] x86, reboot: Use NMI instead of REBOOT_VECTOR to
 stop cpus

On Wed, Dec 21, 2011 at 6:59 AM, Don Zickus <dzickus@...hat.com> wrote:
> On Tue, Dec 20, 2011 at 02:38:39PM -0800, Yinghai Lu wrote:
>> > @@ -230,7 +285,7 @@ struct smp_ops smp_ops = {
>> >        .smp_prepare_cpus       = native_smp_prepare_cpus,
>> >        .smp_cpus_done          = native_smp_cpus_done,
>> >
>> > -       .stop_other_cpus        = native_stop_other_cpus,
>> > +       .stop_other_cpus        = native_nmi_stop_other_cpus,
>> >        .smp_send_reschedule    = native_smp_send_reschedule,
>> >
>> >        .cpu_up                 = native_cpu_up,
>>
>> this broke kexec on our intel nehalem, westmere and sandbridge platforms.
>> system get reset while try to kexec second kernel.
>
>
> Hmm. Ok.  Does the reboot path work correctly?

Yes.

> Vivek showed me that the
> kexec and reboot paths do the same shutdowns.  Perhaps the second kernel
> has trouble dealing with cpus spinning in an NMI context and can't
> properly reset them.

not sure.
when use nonmi_ipi in first kernel, it will work well.

Thanks

Yinghai
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