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Old 25th November 2008
kasse kasse is offline
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Join Date: Jun 2008
Posts: 67
Default fdisk -B does not rewrite the mbr

I have two hard disk, ad0 with freebsd and ad1 with netbsd.

Today I installed a second version of Netbsd on ad1s2 to try things on.
So on ad1 there was ad1s1 old netbsd ad1s2 new netbsd.
The problem is that when I use chainload to read the PBR of the partitions it always loads the same kernel so I guess that it reads the same second stage boot loader /boot. Because:

When I try find /netbsd I get
Then no matter which root (hd1,0,a) or (hd1,1,a) I choose and use:
 kernel /netbsd
on, the found kernels are one and the same - the one for the new netbsd. Somehow I cannot get to the kernel of the old netbsd on slice 1

How do I set the PBR to point to the correct second stage boot loaders?
Does anyone know of a guide similar to http://www.openbsd.org/faq/faq14.html#Boot386 for NetBSD?

Just for some extra info here is the output of fdisk and disklabel:

Disk: /dev/rwd1d
NetBSD disklabel disk geometry:
cylinders: 620181, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
total sectors: 625142448

BIOS disk geometry:
cylinders: 1023, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 625142448

Partition table:
0: NetBSD (sysid 169)
    start 63, size 40960017 (20000 MB, Cyls 0/1/1-2549/164/63), Active
        beg: cylinder    0, head   3, sector 16
        end: cylinder 1023, head  62, sector 16
        PBR appears to be bootable
1: NetBSD (sysid 169)
    start 40961088, size 20480544 (10000 MB, Cyls 2549/181/1-3824/143/63)
        beg: cylinder 1023, head   0, sector  1
        end: cylinder 1023, head  62, sector 16
        PBR appears to be bootable
2: NetBSD (sysid 169)
    start 61441632, size 20480544 (10000 MB, Cyls 3824/144/1-5099/106/63)
        beg: cylinder 1023, head   0, sector  1
        end: cylinder 1023, head  62, sector 16
        PBR appears to be bootable
Bootselector disabled.
Drive serial number: -554148968 (0xdef85b98)
and disklabel
# /dev/rwd1d:
type: unknown
disk: SEG320
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 16
sectors/cylinder: 1008
cylinders: 620181
total sectors: 625142448
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:   1049328  61441632     4.2BSD   1024  8192     0  # (Cyl.  60954 -  61994)
 b:   2097648  62490960       swap                     # (Cyl.  61995 -  64075)
 c:  40960017        63     unused      0     0        # (Cyl.      0*-  40634)
 d: 625142448         0     unused      0     0        # (Cyl.      0 - 620180)
 e:  15235920  64588608     4.2BSD   2048 16384     0  # (Cyl.  64076 -  79190)
 f:   2097648  79824528     4.2BSD   2048 16384     0  # (Cyl.  79191 -  81271)
Within netbsd I can only see the other partitions on wd1 with fdisk, but I cannot mount them like I can in freebsd by mounting slices, because I don't know how to specify the slices. I can only specify the wd1a-p (where I understand c is netbsd partition and d is whole disk) and not partitions or slices.

Since I admit that I do not understand either file system, there are probably things that are not true in the above, but it seems like I am able to navigate in the freebsd with my distorted/faulty perception of the matters.

Last edited by kasse; 27th November 2008 at 11:05 AM.
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