Subject: Re: unknown fs types
To: NetBSD/Atari mailing list <port-atari@NetBSD.ORG>
From: Waldi Ravens <waldi@moacs.indiv.nl.net>
List: port-atari
Date: 05/09/1995 14:43:48
Hallo Leo,

> > > The 'SWP' idea looks good. As for the others, if NetBSD does not support
> > > the type and the partition-id is not modified it will be ok to report
> > > them as MSDOS.
> > 
> > That might be confusing. I think NetBSD `supports' the type FS_OTHER
> > for all "unknown" filesystem types. Wouldn't it make more sense to
> > use that?
> Oops, looking at my own code: That's just what I do!

OK, so type FS_OTHER is completely ignored.

Alas, just a few minutes ago, I found out that the current approach
has two severe problems:

- Partitions containing a filesystem of unknown type are not mapped
  to an sdXY/rsdXY device. Therefor it is impossible to access
  those partitions under NetBSD.

- Changing a partition ID can have unexpected (and possibly nasty)
  side effects. An illustration:

  Disk 4 is divided in 4 partitions. Part. 1 and 2 have ID `BGM'
  and contain gemdos-fss; part. 3 and 4 have ID `NBU' and contain
  ufss. NetBSD gets the following picture:

  	part. 1  =>  sd4d  =>  msdos
  	part. 2  =>  sd4e  =>  msdos
  	part. 3  =>  sd4f  =>  ufs
  	part. 4  =>  sd4g  =>  ufs

  In fstab sd4f is mounted on /var/mail, sd4g is mounted on
  /usr/local.

  Now I decide that partition 2 is no longer going to be used
  under Gemdos, so I change the ID to `FOO':

	part. 1  =>  sd4d  =>  msdos
	part. 2  =>  <ignored>
	part. 3  =>  sd4e  =>  ufs
	part. 4  =>  sd4f  =>  ufs
    
  O dear, now the /usr/local fs will be mounted on /var/mail...

One solution might be to indeed report all unknowns as MSDOS,
however that doesn't look like a particularly clean solution.
Probably there are better alternatives?


Waldi