Re: MSDOS vs diskabel regression in -4, -5 and -current

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

On Tue, 10 Feb 2009, David Laight wrote:
> On Fri, Feb 06, 2009 at 03:49:46PM +0000, Stephen Borrill wrote:
> > I've been asked to try to get an Olympus camera working again after an
> > upgrade to NetBSD 4.0_STABLE. On NetBSD 3.1, the fictitious disklabel
> > correctly has an MSDOS partition as partition e (and thus can be easily
> > mounted with mount_msdos /dev/sd0e /mnt). On NetBSD 4.0 and later, the
> > fdisk partition table appears subtly different and no MSDOS partition is
> > seen in disklabel; rather there is a 4.2BSD partition as partition a.
>
> > sd0: fabricating a geometry
> > sd0: mbr partition exceeds disk size
>
> I suspect this is the cause of the problem.
> The code is validating the mbr data against the reported media size,
> detecting that it is invalid so ignoring the mbr.

I've been sent one of the offending cameras now.

I used dd to clear the camera's memory and then fdisk to partition it 
(accepting defaults in the main). This started partition 0 at 32 instead 
of 1 (as when the camera formatted itself - fdisk didn't like this "Track 
zero is reserved for the BIOS"):

Disk: /dev/rsd0d
NetBSD disklabel disk geometry:
cylinders: 6, heads: 64, sectors/track: 32 (2048 sectors/cylinder)
total sectors: 14143

BIOS disk geometry:
cylinders: 7, heads: 64, sectors/track: 32 (2048 sectors/cylinder)
total sectors: 14143

Partition table:
0: Primary DOS with 12 bit FAT (sysid 1)
    start 32, size 14143 (7 MB, Cyls 0-6/58/31)
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.

After newfs_msdos (or format from Windows), disklabel was still unhappy 
with the offsets set to 0 instead of 32

# /dev/rsd0d:
type: SCSI
disk: FE210/X775
label: fictitious
flags: removable
bytes/sector: 512
sectors/track: 32
tracks/cylinder: 64
sectors/cylinder: 2048
cylinders: 6
total sectors: 14143
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

4 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:     14143         0     4.2BSD      0     0     0  # (Cyl.      0 - 6*)
 d:     14143         0     unused      0     0        # (Cyl.      0 - 6*)

--
Stephen