Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764209AbYBHRXg (ORCPT ); Fri, 8 Feb 2008 12:23:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759476AbYBHRXT (ORCPT ); Fri, 8 Feb 2008 12:23:19 -0500 Received: from blaine.gmane.org ([80.91.229.8]:47840 "EHLO hugh.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758904AbYBHRXR (ORCPT ); Fri, 8 Feb 2008 12:23:17 -0500 X-Greylist: delayed 1694 seconds by postgrey-1.27 at vger.kernel.org; Fri, 08 Feb 2008 12:23:17 EST To: Ingo Molnar Cc: Neil Horman , public-kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@hugh.gmane.org, public-linux-kernel-u79uwXL29TY76Z2rM5mHXA@hugh.gmane.org, public-mingo-H+wXaHxf7aLQT0dZR+AlfA@hugh.gmane.org, "Eric W. Biederman" , "H. Peter Anvin" , public-tglx-hfZtesqFncYOwBW4kG4KsQ@hugh.gmane.org, Vivek Goyal Subject: Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die_nmi path From: Andi Kleen References: <20080206192555.GA24910@hmsendeavour.rdu.redhat.com> <20080206220001.GA15155@elte.hu> <20080206224805.GD11886@redhat.com> <47AA3B16.7000507@zytor.com> <20080206233657.GB12393@elte.hu> <20080207121719.GA29279@hmsreliant.think-freely.org> <20080207122404.GA8195@elte.hu> Date: Fri, 08 Feb 2008 17:54:29 +0100 In-Reply-To: <20080207122404.GA8195@elte.hu> (Ingo Molnar's message of "Thu\, 7 Feb 2008 13\:24\:04 +0100") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 812 Lines: 25 Ingo Molnar writes: > > try a dummy iret, something like: > > asm volatile ("pushf; push $1f; iret; 1: \n"); > > to get the CPU out of its 'nested NMI' state. (totally untested) Just if you do this while running on the NMI stack (and I think you do if you insert it at the same place as Neil's original patch) and another NMI happens for some reason you will be dead because your stack will corrupt. If you really want nested NMIs you would need to fix up the NMI stacks first by pointing them below your own stack. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/