From owner-freebsd-current@FreeBSD.ORG Fri Jun 12 19:11:02 2015 Return-Path: Delivered-To: current@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id E6092183 for ; Fri, 12 Jun 2015 19:11:02 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from outbound3.ore.mailhop.org (erouter6.ore.mailhop.org [54.187.213.119]) by mx1.freebsd.org (Postfix) with SMTP id BFA6486B for ; Fri, 12 Jun 2015 19:11:02 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from ilsoft.org (unknown [73.34.117.227]) by outbound3.ore.mailhop.org (Halon Mail Gateway) with ESMTPSA; Fri, 12 Jun 2015 19:10:49 +0000 (UTC) Received: from revolution.hippie.lan (revolution.hippie.lan [172.22.42.240]) by ilsoft.org (8.14.9/8.14.9) with ESMTP id t5CJAs12009173; Fri, 12 Jun 2015 13:10:54 -0600 (MDT) (envelope-from ian@freebsd.org) Message-ID: <1434136254.1415.47.camel@freebsd.org> Subject: Re: obtaining a minidump from panic() called from NMI handler From: Ian Lepore To: Konstantin Belousov Cc: Maksim Yevmenkin , Andriy Gapon , "current@freebsd.org" Date: Fri, 12 Jun 2015 13:10:54 -0600 In-Reply-To: <20150612185521.GE2080@kib.kiev.ua> References: <557B1905.80307@FreeBSD.org> <20150612185521.GE2080@kib.kiev.ua> Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.12.10 FreeBSD GNOME Team Port Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Jun 2015 19:11:03 -0000 On Fri, 2015-06-12 at 21:55 +0300, Konstantin Belousov wrote: > On Fri, Jun 12, 2015 at 11:49:01AM -0700, Maksim Yevmenkin wrote: > > Andriy, > > > > >> i have a question about obtaining minidump as result of panic() being > > >> called from nmi handler. basically, i have a way to trigger nmi, and, > > >> i would like to panic() system and obtain a minidump. > > >> > > >> i have modified isa_nmi() to appropriately inspect bits and return > > >> non-zero return code. i have turned off machdep.kdb_on_nmi knob (set > > >> it to zero). i have confirmed that amd64 trap() is called with correct > > >> T_NMI type. i've also confirmed that panic() is called from amd64's > > >> trap(). > > >> > > >> the issue i have is that system is rebooting too early. basically, it > > >> looks like minidump is started, but, for whatever reason, other cpus > > >> are not completely stopped (or may be they are panic()ing again) and > > >> system just reboots without having complete the minidump. > > >> > > >> the issue is not present when machdep.kdb_on_nmi is set to 1. in this > > >> case, system drops into ddb prompt and 'call doadump' works as > > >> expected. for various reasons i can not use ddb, and, would like to > > >> have system save nmi triggered minidump completely unattended. > > >> > > >> can someone please give me a clue as to what i should be looking into > > >> to make this work? > > > > > > could it be that more than one CPUs get the NMI at the same time? > > > > i guess, its possible. is there an easy way to check for that? > > > > > IF yes, then the current code wouldn't handle that well - each of the NMI-ed > > > CPUs will try to stop all others with another NMI and it will wait until each of > > > those CPUs sets an acknowledgement bit in its NMI handler. This scheme works > > > fine if there's only one CPU that wants to become the master, but results in a > > > deadlock otherwise. > > > > that makes sense. i don't observe deadlock, but, simple reboot. > > I believe I posted patches to serialize ddb entrance or panics due to nmi. > I do not have references handy, you could search lists. > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" That was on freebsd-arch in July 2014. -- Ian