linux-kernel - Re: [PATCH -v3 5/6] x86, NMI, treat unknown NMI as hardware error

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Date:	Wed, 20 Oct 2010 14:12:37 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Robert Richter <robert.richter@....com>
Subject: Re: [PATCH -v3 5/6] x86, NMI, treat unknown NMI as hardware error

Hi, Don,

On Tue, 2010-10-12 at 05:20 +0800, Don Zickus wrote:
> > @@ -366,6 +368,15 @@ unknown_nmi_error(unsigned char reason,
> >  	if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
> >  			NOTIFY_STOP)
> >  		return;
> > +	/*
> > +	 * On some platforms, hardware errors may be notified via
> > +	 * unknown NMI
> > +	 */
> > +	if (unknown_nmi_as_hwerr)
> > +		panic(
> > +		"NMI for hardware error without error record: Not continuing\n"
> > +		"Please check BIOS/BMC log for further information.");
> > +
> >  #ifdef CONFIG_MCA
> >  	/*
> >  	 * Might actually be able to figure out what the guilty party
> 
> The only quirk I have left is the above piece, which is basically a
> philosophy difference with Robert and myself.  Where we believe it should
> be on the die_chain and Andi and yourself would like to see it explicitly
> called out.

After some more thought, I found this is different from DIE_NMI and
DIE_NMI_IPI case. I think the code added is for general unknown NMI
processing instead of a device driver. What we do is not to add special
processing for some devices, but treat unknown NMI as hardware error
notification in general and use a white list to deal with broken
hardware and stone age machine. Do you agree?

If so, it should not be turned into a notifier block unless you want to
turn all general unknown NMI processing code into a notifier block.

Best Regards,
Huang Ying


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