From owner-cvs-src@FreeBSD.ORG Wed Dec 15 14:38:37 2004 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 50FDD16A58B for ; Wed, 15 Dec 2004 14:38:37 +0000 (GMT) Received: from mail1.speakeasy.net (mail1.speakeasy.net [216.254.0.201]) by mx1.FreeBSD.org (Postfix) with ESMTP id BAAEA43D46 for ; Wed, 15 Dec 2004 14:38:36 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 21366 invoked from network); 15 Dec 2004 14:38:36 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 15 Dec 2004 14:38:36 -0000 Received: from slimer.baldwin.cx (slimer.baldwin.cx [192.168.0.16]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id iBFEcMVd002503; Wed, 15 Dec 2004 09:38:33 -0500 (EST) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Kris Kennaway Date: Tue, 14 Dec 2004 21:48:48 -0500 User-Agent: KMail/1.6.2 References: <200411300618.iAU6IkQX065609@repoman.freebsd.org> <41BF6F44.2090407@root.org> <20041215001034.GA60875@xor.obsecurity.org> In-Reply-To: <20041215001034.GA60875@xor.obsecurity.org> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200412142148.48019.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: Nate Lawson Subject: Re: cvs commit: src/sys/i386/i386 vm_machdep.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Dec 2004 14:38:37 -0000 On Tuesday 14 December 2004 07:10 pm, Kris Kennaway wrote: > On Tue, Dec 14, 2004 at 02:55:00PM -0800, Nate Lawson wrote: > > >Erm, well, that's not always easy since sometimes when you panic you > > > can't talk to the other CPUs for whatever reason. Putting back the > > > proxy reset doesn't hurt for now but does restore functionality in at > > > least some cases. I'd rather have that then certain hard panics not > > > get into ddb because we couldn't get onto the BSP to run ddb. > > > > Perhaps you could give me some pointers on what is counted on to be > > working when panic() is called? I can't come up with a situation where > > the proxy code couldn't be used upon entry to ddb. If there were any > > cases like this, the proxy code wouldn't work for cpu_reset() either. > > Also, in such a case, it's hard to see how ddb could be usable since it > > tries to stop other processors, which requires similar code to the proxy. > > > > Or in other words, if you have enough capability to call panic() or > > break to ddb, then you have enough resources to do an IPI and get onto > > the BSP. > > NB: DDB often isn't usable on SMP machines thesedays, and will hang > when a panic tries to enter it. Try debug.kdb.stop_cpus=0 (sysctl and tunable) to prevent KDB from trying to stop the other CPUs. Another possible fix that ups@ has talked about is changing IPI_STOP to use an NMI rather than a vector (you can send NMI IPIs via the local APIC) so that IPI_STOP is more reliable. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org