From owner-freebsd-questions Mon Sep 1 18:31:47 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id SAA05824 for questions-outgoing; Mon, 1 Sep 1997 18:31:47 -0700 (PDT) Received: from nico.telstra.net (nico.telstra.net [139.130.204.16]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id SAA05819 for ; Mon, 1 Sep 1997 18:31:41 -0700 (PDT) Received: from freebie.lemis.com (gregl1.lnk.telstra.net [139.130.136.133]) by nico.telstra.net (8.6.10/8.6.10) with ESMTP id LAA25776; Tue, 2 Sep 1997 11:31:08 +1000 Received: (grog@localhost) by freebie.lemis.com (8.8.7/8.6.12) id LAA21379; Tue, 2 Sep 1997 11:01:07 +0930 (CST) Message-ID: <19970902110107.09113@lemis.com> Date: Tue, 2 Sep 1997 11:01:07 +0930 From: Greg Lehey To: Sara Gronim Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Kernel question References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.81e In-Reply-To: ; from Sara Gronim on Mon, Sep 01, 1997 at 08:56:42PM -0400 Organisation: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8250 Fax: +61-8-8388-8250 Mobile: +61-41-739-7062 WWW-Home-Page: http://www.lemis.com/~grog Fight-Spam-Now: http://www.cauce.org Sender: owner-freebsd-questions@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Mon, Sep 01, 1997 at 08:56:42PM -0400, Sara Gronim wrote: > Hi, this is my first time writing to this service. > > Can i leave my generice kernel in place, build a new custom kernel and > then implemenet the new kernel at the boot prompt? Yes. > Is this possible, smart or in any way less risky than implementing > the new kernel and keeping a copy of the old one? No. It's pretty much the same thing. To understand why, you need to understand what the Boot: prompt does. When, it appears, it gives you about 5 seconds to enter something. If you don't, it'll try to boot the file /kernel from its default partition, normally /dev/sd0a (SCSI) or /dev/wd0a (IDE). If you install a custom kernel, you have the choice of renaming the old one, say, /kernel.GENERIC, and installing the new kernel as /kernel. Or you can leave the generic kernel where it is, and install the new kernel as, say, /kernel.ALLMINE. In either case, if you want to boot the kernel not called /kernel, you just enter its name at the Boot: prompt. Obviously, it's better to name the kernel you use more often /kernel. Having said that, there are some problems involved with multiple kernels. Some of the programs in /sbin and /usr/sbin are sensitive to the version of the kernel. ps, in particular, will often not work with a kernel of a different version. On the other hand, you shouldn't see any problems with kernels built from the same version but with different config files. Greg