Re: kern/40360: fictitious disklabels do not handle devices without an MBR

["Jared D. McNeill" <jmcneill%invisible.ca@localhost>]

The following reply was made to PR kern/40360; it has been noted by GNATS.

From: "Jared D. McNeill" <jmcneill%invisible.ca@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, 
 netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/40360: fictitious disklabels do not handle devices without
 an MBR
Date: Sat, 10 Jan 2009 15:45:06 -0500

 David Laight wrote:
 > The following reply was made to PR kern/40360; it has been noted by GNATS.
 > 
 > From: David Laight <david%l8s.co.uk@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 >      netbsd-bugs%netbsd.org@localhost
 > Subject: Re: kern/40360: fictitious disklabels do not handle devices without 
 > an MBR
 > Date: Sat, 10 Jan 2009 20:39:48 +0000
 > 
 >  On Sat, Jan 10, 2009 at 07:25:01PM +0000, jmcneill%invisible.ca@localhost 
 > wrote:
 >  > >Synopsis:       fictitious disklabels do not handle devices without an 
 > MBR
 >  ...
 >  > >Description:
 >  >   When inserting a USB device that only contains a FAT filesystems,
 >  >   the auto-generated disklabel incorrectly reports a 4.2BSD filesystem
 >  >   at the beginning of the device.
 >  
 >  The filesystem type in the disklabel is fairly irrelevant.
 >  Nothing during mount looks at it - so it is really just a comment.
 >  (except maybe for swap).
 >  
 >  It is more important that the fictitious label contain a partition
 >  that covers the entire disk.
 
 People look at it[1] and HAL uses it to figure out which mount_* to 
 call. Our HAL backend now has a nasty hack that uses libvolume_id to 
 ignore disklabel if libvolume_id thinks a partition is 'vfat'.
 
 Also, doesn't /sbin/mount use it to guess which mount_* to use when -t 
 isn't specified?
 
 Cheers,
 Jared
 
 [1] http://mail-index.netbsd.org/netbsd-users/2009/01/07/msg002689.html