Subject: Re: Supporting sector size != DEV_BSIZE (fwd)
To: Trevin Beattie <trevin@xmission.com>
From: Konrad Schroder <perseant@hhhh.org>
List: tech-kern
Date: 06/10/2002 14:21:44
On Mon, 10 Jun 2002, Trevin Beattie wrote:

> As I've said before, I don't want to do anything that will break existing
> file systems, if I can avoid it.  OTOH, since the existing kernel is broken
> WRT sector size != DEV_BSIZE, I think it's safe to base any changes on the
> premise that DEV_BSIZE == sector size on all working file systems.

I don't; not because our current kernel works for DEV_BSIZE!=512, which
maybe it doesn't, but because it definitely did work for someone once.
(Maybe they didn't run the current NetBSD, or even NetBSD at all, that's
not the point.)

If we had a mechanism for addressing filesystems that had been built with
DEV_BSIZE=1024, we could mount old filesystems for systems that were built
that way, and worked just fine when they were built; the NeXT comes to
mind as a system that shipped with 1kB sectors.  Our FFS will currently
mount 4.2-FFSes (read-only?) and dtrt;  if we change the filesystem(s)
to understand different sector sizes than 512, we should be able to get
these historical 1k-sector fss "for free".

						Konrad Schroder
						perseant@hhhh.org