From owner-freebsd-stable@FreeBSD.ORG Wed Jun 28 14:59:36 2006 Return-Path: X-Original-To: freebsd-stable@freeBSD.org Delivered-To: freebsd-stable@freeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8AB4516A49E; Wed, 28 Jun 2006 14:59:36 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id 83325444B3; Wed, 28 Jun 2006 14:35:04 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 33FE446C17; Wed, 28 Jun 2006 10:34:59 -0400 (EDT) Date: Wed, 28 Jun 2006 15:34:59 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: "Marc G. Fournier" In-Reply-To: <20060626110636.I1114@ganymede.hub.org> Message-ID: <20060628153222.I65342@fledge.watson.org> References: <20060626100949.G24406@fledge.watson.org> <20060626081029.L1114@ganymede.hub.org> <20060626140333.M38418@fledge.watson.org> <20060626110636.I1114@ganymede.hub.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-acpi@freebsd.org, freebsd-stable@freeBSD.org, Pete French Subject: Re: FreeBSD 6.x CVSUP today crashes with zero load ... X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Jun 2006 14:59:36 -0000 On Mon, 26 Jun 2006, Marc G. Fournier wrote: >> I think this is a useful activity, especially if you've already run >> extensive memory testing on the box. If you haven't yet done that, I >> encourage you to take a break from buildworld's and make sure the memory >> tests pass. I spent several months on and off trying to track down a bug a >> few years ago, which turned out to be a one bit error in memory on the box. >> It would appear and disappear based on how the memory page was used -- for >> debugging kernels, it consistently got mapped to padding in the kernel's >> bss. For non-debugging kernels, it typically manifested in other usable >> kernel momory. Changes in kernel versions would move the bit around kernel >> memory and user memory, resulting in hard to debug failure modes. I wish >> I'd run the memory test earlier, but the lesson is clear! > > Is there something that I can run *from* FreeBSD, remotely, to do this? Not that I know of. In the past, the discussion has been held about adopting a memory tester into the boot loader, which is almost certainly the right place to put it (before VM kicks off and we load many megabytes of critical data structures, etc). Some hands to make this happen would be most welcome. Robert N M Watson Computer Laboratory University of Cambridge