FS impl.

[Stephan Uphoff]

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