From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 19 Jun 2002 01:18:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 19 Jun 2002 01:18:22 -0400 Received: from mail.goquest.com ([63.172.73.8]:28840 "HELO mail.goquest.com") by vger.kernel.org with SMTP id ; Wed, 19 Jun 2002 01:18:21 -0400 Content-Type: text/plain; charset=US-ASCII From: "Michael S. Zick" To: Rob Landley , zaimi@pegasus.rutgers.edu, linux-kernel@vger.kernel.org Subject: Re: kernel upgrade on the fly Date: Wed, 19 Jun 2002 00:09:32 -0500 X-Mailer: KMail [version 1.2] References: <20020619010945.6725B7D9@merlin.webofficenow.com> In-Reply-To: <20020619010945.6725B7D9@merlin.webofficenow.com> MIME-Version: 1.0 Message-Id: <02061900093200.00787@localhost.localdomain> Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 18 June 2002 02:37 pm, Rob Landley wrote: > On Tuesday 18 June 2002 05:21 pm, zaimi@pegasus.rutgers.edu wrote: > > Hi all, > > > > has anybody worked or thought about a property to upgrade the kernel > > while the system is running? ie. with all processes waiting in their > > queues while the resident-older kernel gets replaced by a newer one. > > > Would anybody else think this to be an interesting property to have for > > the linux kernel or care to comment on this idea? > > Sure, I know two industries that do such a thing (almost); Spacecraft and the Telephone Company (any/all); I did say almost... I'll speak of the telephone industry, because I am more familar with it... There they use two (or more) machines, running near the same program... The one connected to the outside world of hardware is duplicating the event in a message, sent to the second... The second, instead of listening to the outside world is listening to the messages, duplicating all of the program logic except the hardware i/o. The memory data structures are identical between the two. When disaster happens... Machine two rolls out it's listening modules, rolls in the i/o modules, sends signal to hardware buss switch to give it the system buss. Then the fun begins... Recover the hardware (or at least the billing information). Note the three points above: 1) Near identical programs 2) Identical data structures 3) Two sets of CPU hardware Switching from linux-2.4.x to linux-2.6.x doesn't qualify; The person who asked this question wants to do it on a single machine - The price just went way up... Linux uses internal data structures when and wherever they are needed. Updating them all to be consistant would be a real b.... Probably you would have to start from scratch and rebuild them... Hmm, I think I just said "reboot" the machine with the new kernel. Mike