From owner-freebsd-hackers Tue Apr 6 16:26:42 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (Postfix) with ESMTP id 38ABC15233 for ; Tue, 6 Apr 1999 16:26:37 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id IAA10995 for ; Wed, 7 Apr 1999 08:54:38 +0930 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id IAA12754 for hackers@freebsd.org; Wed, 7 Apr 1999 08:54:36 +0930 (CST) Message-ID: <19990407085435.M2142@lemis.com> Date: Wed, 7 Apr 1999 08:54:35 +0930 From: Greg Lehey To: FreeBSD Hackers Subject: Separate boot partition? Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93.2i WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG One of the most asked-for features currently not implemented in Vinum is to be able to have the root file system running under Vinum. It looks simple enough, but there's a powerful chicken-and-egg problem in there: the bootstrap doesn't run Vinum, so it can't read the kernel from a Vinum volume. There is little provision to remount the root file system elsewhere than where the bootstrap thinks it is, and since by this time there are open file descriptors, it's difficult to change this behaviour. I've been thinking about this, and the best I can come up with is a separate boot file system, like some System Vs do. In System V the interest seems to come from the fact that the bootstraps are too stupid to understand file systems such as VxFS, but basically they just contain the kernel. I was thinking of additional information such as the name of the root file system, though of course that could be compiled into the kernel. The sequence would then be: boot loads the kernel from /boot/kernel. kernel initializes, including Vinum if desired, and loads the root file system The kernel data file is still available via a symlink from /kernel to /boot/kernel, or as a copy somewhere. Note that the original file from which the kernel is loaded is no longer needed once the kernel was loaded. Some programs, such as ps, may use the kernel file to extract information about the kernel, but this doesn't have to be from the same file as from which the kernel was loaded: the file just needs the same contents, so a copy would be OK. Comments? Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message