From owner-freebsd-hackers@FreeBSD.ORG Sat May 7 03:42:35 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 DADB816A4D8 for ; Sat, 7 May 2005 03:42:35 +0000 (GMT) Received: from duchess.speedfactory.net (duchess.speedfactory.net [66.23.201.84]) by mx1.FreeBSD.org (Postfix) with SMTP id 160BB43D6B for ; Sat, 7 May 2005 03:42:35 +0000 (GMT) (envelope-from ups@tree.com) Received: (qmail 8493 invoked by uid 89); 6 May 2005 23:19:40 -0000 Received: from duchess.speedfactory.net (66.23.201.84) by duchess.speedfactory.net with SMTP; 6 May 2005 23:19:40 -0000 Received: (qmail 5031 invoked by uid 89); 6 May 2005 21:59:39 -0000 Received: from unknown (HELO palm.tree.com) (66.23.216.49) by duchess.speedfactory.net with SMTP; 6 May 2005 21:59:39 -0000 Received: from [127.0.0.1] (localhost.tree.com [127.0.0.1]) by palm.tree.com (8.12.10/8.12.10) with ESMTP id j46LxHw6027107; Fri, 6 May 2005 17:59:17 -0400 (EDT) (envelope-from ups@tree.com) From: Stephan Uphoff To: Kip Macy In-Reply-To: References: Content-Type: text/plain Message-Id: <1115416757.96600.9391.camel@palm> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Fri, 06 May 2005 17:59:17 -0400 Content-Transfer-Encoding: 7bit cc: freebsd-hackers@freebsd.org cc: David Parfitt Subject: Re: FS impl. 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: Sat, 07 May 2005 03:42:36 -0000 On Fri, 2005-05-06 at 16:01, Kip Macy wrote: > On Fri, 6 May 2005, David Parfitt wrote: > > > Hi - > > I have been trying to write my own UFS-like filesystem > > implementation for fun. I had read somewhere that UFS was developed in > > user space (correct me if I'm wrong on that one) and then moved over > > to kernel-space. I was wondering if there are any existing facilities > > in the kernel source tree that would allow me to develop an fs in user > > space easily or with a little tweaking? As of right now, I have to > > develop, compile, panic, reboot, debug etc. which is frustrating and > > time consuming. > > > I can't speak for user-space utilities, but using xen as a development > environment would dramatically shorten the panic and reboot cycle. In addition, > you don't require a 2nd machine to debug with GDB. Just a thought. If booting > Linux makes you itch, NetBSD support for acting as the control plane is supposed > to be stable. I agree. I used this approach with vmware a while ago and was more than happy. >From what I see xen reboots are even faster (I only tried Xen with NetBSD and linux so far). Hopefully Kip's work will make it into current before I need a setup like this for FreeBSD. An alternative would be a fast booting second machine with PXE (network) booting. (real server hardware takes forever to boot - use consumer boxes without ECC memory,SCSI, memory test,...) Things have changed a bit since UFS was developed making development in user space more difficult due to extra functionality that would need to be ported/emulated to/in user space. There is also no pressure to do this since development in kernel space is so much easier these days. This being said I highly recommend writing user space test applications that integrate modules/functions from your FS whenever possible. Stephan