From owner-freebsd-hackers@FreeBSD.ORG Mon Jan 24 20:21:13 2005 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BC1A016A4CE for ; Mon, 24 Jan 2005 20:21:13 +0000 (GMT) Received: from mail09.syd.optusnet.com.au (mail09.syd.optusnet.com.au [211.29.132.190]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2329543D53 for ; Mon, 24 Jan 2005 20:21:12 +0000 (GMT) (envelope-from PeterJeremy@optushome.com.au) Received: from cirb503493.alcatel.com.au (c211-30-75-229.belrs2.nsw.optusnet.com.au [211.30.75.229]) j0OKL03s032619 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Tue, 25 Jan 2005 07:21:01 +1100 Received: from cirb503493.alcatel.com.au (localhost.alcatel.com.au [127.0.0.1])j0OKL07l031750; Tue, 25 Jan 2005 07:21:00 +1100 (EST) (envelope-from pjeremy@cirb503493.alcatel.com.au) Received: (from pjeremy@localhost)j0OKL0Kx031749; Tue, 25 Jan 2005 07:21:00 +1100 (EST) (envelope-from pjeremy) Date: Tue, 25 Jan 2005 07:20:59 +1100 From: Peter Jeremy To: Christian Laursen Message-ID: <20050124202059.GA30458@cirb503493.alcatel.com.au> References: <86pszu639o.fsf@borg.borderworlds.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86pszu639o.fsf@borg.borderworlds.dk> User-Agent: Mutt/1.4.2i cc: hackers@freebsd.org Subject: Re: Resuming from a crashdump X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Jan 2005 20:21:13 -0000 On Mon, 2005-Jan-24 20:22:27 +0100, Christian Laursen wrote: >The idea would be to force the system to "crash" and make a >dump on a dedicated partition. On boot after initializing devices >but before mounting /, the kernel would check that partition and >if it found a dump there restore it to the machine's memory, >reinitialize devices and continue where it left off. At a process level, this is what emacs and TeX used to do many years ago (have a look for "undump"). What you are describing is basically the same as the suspend-to-disk that some laptops support. Implementing it is non-trivial because each I/O device needs to be re-initialised into the state it was before the suspend. You also have to work out how to handle the intervening (lost) time - what happens to at/cron jobs and timers that should have fired in the intervening period? Note that in many circumstances, you will lose all external TCP connections when keep-alive timers expire in remote systems and firewalls. -- Peter Jeremy