Unable to modify sysid with Fdisk

[David Scialom]

Hello,

It seems that it  is impossible to modify the sysid with fdisk since FreeBSD
6.2. I am actually using FreeBSD7.0.
When I want to modify my the sysid from 165(ufs) to 12(Fat32) i get the
message "Geom not found: da0" and no change is made: da0 is stock with sysid
= 165. The detail are provided below. I tried also to do the same from the
install FreeBSD CD without success.

As someone a solution ?

Zurich# fdisk -u da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

Do you want to change our idea of what BIOS thinks ? [n]
*fdisk: invalid fdisk partition table found*
Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 32, size 2066400 (1008 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1008/ head 63/ sector 32
Do you want to change it? [n] y
Supply a decimal value for "sysid (165=FreeBSD)" [165] 12
Supply a decimal value for "start" [32]
Susysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 2066400 (1008 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1008/ head 63/ sector 32
Are we happy with this entry? [n] y
The data for partition 2 is:
<UNUSED>
Do you want to change it? [n]
The data for partition 3 is:
<UNUSED>
Supply a decimal value for "size" [2066400]
Explicitly specify beg/end address ? [n]
sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 2066400 (1008 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1008/ head 63/ sector 32
Are we happy with this entry? [n] y
The data for partition 2 is:
<UNUSED>
Do you want to change it? [n]
The data for partition 3 is:
<UNUSED>
Do you want to change it? [n]
The data for partition 4 is:
<UNUSED>
Do you want to change it? [n]
Partition 1 is marked active
Do you want to change the active partition? [n] y
Supply a decimal value for "active partition" [1]
Are you happy with this choice [n] y

We haven't changed the partition table yet.  This is your last chance.
parameters extracted from in-core disklabel are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

Information from DOS bootblock is:
1: sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 2066400 (1008 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1008/ head 63/ sector 32
2: <UNUSED>
3: <UNUSED>
4: <UNUSED>
Should we write new partition table? [n] y
fdisk: Geom not found: "da0"
Zurich# fdisk da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)

fdisk: invalid fdisk partition table found
Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 32, size 2066400 (1008 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1008/ head 63/ sector 32
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSE