Date: Fri, 06 May 2005 17:59:17 -0400 From: Stephan Uphoff <ups@tree.com> To: Kip Macy <kmacy@netapp.com> Cc: David Parfitt <diparfitt@gmail.com> Subject: Re: FS impl. Message-ID: <1115416757.96600.9391.camel@palm> In-Reply-To: <Pine.LNX.4.44.0505061259000.3568-100000@barleywine.eng.netapp.com> References: <Pine.LNX.4.44.0505061259000.3568-100000@barleywine.eng.netapp.com>
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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
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