On Wed, 3 May 2000, Richard Gooch wrote:
> I think you're referring here to a "split" devfs, where each driver
> exports a mini-devfs. In such an environment, your mount traps would
> probably be good.
>
> However, I don't think the mini-devfs idea is a good approach. There
> are good reasons for having a unified tree. For one thing, there is
> the issue of mounting /. For another, some drivers (i.e. cdrom) need
> linkages (not just symlinks) into other parts of the devfs namespace.
Details, please? Notice that we are going to get equivalent of Plan 9
bind() RSN - it works in my tree right now and all I need to merge it into
the main tree is to sort out the autofs4 stuff. Well, since Jeremy wants
to postpone the autofs4 changes (i.e. not go for traps-based scheme right
now) - fine, I'm merging the autofs4 patches that switch the thing to new
linkage, toss in the ten-liner for knfsd (there linkage-related stuff is
minimal), test it and submit to Linus. mount -t bind goes immediately
after that. So getting the linkage between parts of unified tree and doing
that without any symlinks is trivial.
And what's up with mounting /?
> Also, it would be hard (or impossible) for related drivers to share
> the same directory (i.e. SCSI subsystem). At the least, there would
> have to be more co-operation between drivers. Compare this to the
> current devfs implementation where things are fairly modular and
> independent.
Why? union-mount their trees on /dev/scsi and you are done. No?
> Anyway, while these mount traps are a good thing, particularly for
> autofs, I don't think they're going to help simplify devfs (without
> castrating devfs and probably breaking the Linus-mandated
> namespace;-).
I wouldn't worry too much about the namespace breakage - check the bind(2)
manpage in Plan 9 to see what it is coming (their manpages are available
and searchable on http://www.freebsd.org/docs.html#man, along with the
manpages from a lot of other systems - kudos to Wolfram Schneider and
freebsd.org folks; very convenient resource they had put there). We'll get
tools that can repair such breakage.
