linux-kernel - Re: new text patching for review

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Message-ID: <20070721061945.GC5293@one.firstfloor.org>
Date:	Sat, 21 Jul 2007 08:19:45 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc:	Zachary Amsden <zach@...are.com>, Andi Kleen <andi@...stfloor.org>,
	jbeulich@...ell.com, "S. P. Prasanna" <prasanna@...ibm.com>,
	linux-kernel@...r.kernel.org, patches@...-64.org,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: new text patching for review

On Fri, Jul 20, 2007 at 11:17:49AM -0400, Mathieu Desnoyers wrote:
> * Zachary Amsden (zach@...are.com) wrote:
> > Mathieu Desnoyers wrote:
> > >Yes, kprobes is case 1: atomic update. And we don't even have to bother
> > >about Intel's erratum. This one is ok. That's mainly the
> > >alternatives/paravirt code I worry about.
> > >  
> > 
> > Paravirt and alternatives should all be ok because they are done before 
> > SMP bringup and with NMIs disabled.  NMI watchdog is not setup until 
> > smp_prepare_cpus/check_nmi_watchdog, which happens way later, not during 
> > parse_args/setup_nmi_watchdog, which just decides which type of watchdog 
> > to setup.
> > 
> 
> I'm not so sure about this. You are right in that it has nothing to do
> with parse_args, but I just went in detail through the source, and the
> order seems to be:
> 
> 1 - NMI is activated
> 2 - MCE is activated
> 3 - alternatives are applied

Yes I was wrong on this. I now added code to disable them again -- see 
the later patch I posted

-Andi
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