Message-ID: <47AA16CA.6000003@zytor.com>
Date: Wed, 06 Feb 2008 12:21:30 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Neil Horman <nhorman@redhat.com>
CC: Vivek Goyal <vgoyal@redhat.com>, Neil Horman <nhorman@tuxdriver.com>,
       tglx@linutronix.de, mingo@redhat.com, kexec@lists.infradead.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die_nmi
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References: <20080206192555.GA24910@hmsendeavour.rdu.redhat.com> <20080206194040.GA11886@redhat.com> <20080206201223.GA25183@hmsendeavour.rdu.redhat.com>
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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
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