Subject: Re: 32 bit dev_t, Revision 2
To: None <tech-kern@NetBSD.ORG>
From: Zdenek Salvet <salvet@horn.ics.muni.cz>
List: tech-kern
Date: 01/13/1998 19:02:40
> > back on topic, can someone 'splain to me why device special files are still
> > inside a UFS/FFS container with special "MAKEDEV" scripts? if we can do
> > /proc it seems to me that /dev can be a special file system whose entries
> > are _made_ at successful probe time, using monotonically increasing dev_t's
> > with an opaque internal structure? ted says this has been done in some
> > form. if we're going to pull dev_t through a knothole backward and touch
> > the kernel in 125 places to do it, why not do the Right Thing and just stop
> > trying to figure out whether 12/20 is a good split or whether MI and MD need
> > different ranges and whether one or two tables are the right approach. we
> > KNOW this isn't the right approach, why are we taking it anyway?
>
> Um.. probably because:
>
> (1) There are several problems with a "devfs" approach, including
> non-persistence of chmod's and symlinks.
>
> (2) There are some programs out there that like to compare dev_t's
> to see if e.g. file foo is on the same file system as file bar.
(3) AFAIK, dev_t's of block devices with NFS exported filesystems
must be persistent across reboots and reconfigurations
(this can be avoided with translation tables in server code
filled by /etc/rc from database file but that's really ugly IMHO).
I would like devfs as optional filesystem, that anybody who knows what he is
doing could use as target of custom symlinks created in normal /dev.
Compatility & prior art:
Solaris looks like this if you delete /etc/rcS.d/S60devlinks :-)
--
Zdenek Salvet salvet@ics.muni.cz
----------------------------------------------------------------------------
If God had meant for us to be in the Army,
we would have been born with green, baggy skin.