linux-kernel - Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die

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Message-ID: <20080206210407.GB25183@hmsendeavour.rdu.redhat.com>
Date:	Wed, 6 Feb 2008 16:04:07 -0500
From:	Neil Horman <nhorman@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Neil Horman <nhorman@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
	Neil Horman <nhorman@...driver.com>, tglx@...utronix.de,
	mingo@...hat.com, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die_nmi path

On Wed, Feb 06, 2008 at 12:21:30PM -0800, H. Peter Anvin wrote:
> Neil Horman wrote:
> >Can an APIC accept an NMI while already handling an NMI?  I didn't think 
> >they
> >would interrupt one another, but rather, pend until such time as the 
> >previous
> >NMI was cleared
> 
> The CPU certainly won't (there is a hidden flag that's cleared on IRET 
> which disables NMI; it's possible to re-enable NMI by executing a dummy 
> IRET inside the NMI handler.)
> 
> 	-hpa

So that would be another solution I would expect.  Would you rather I
investigate that, or is the proposed solution more reasonable?

Neil


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 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman@...hat.com
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 *http://pgp.mit.edu
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