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From: sja@tekla.fi (Sakari Jalovaara)
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Date: Sat, 1 Feb 1997 11:12:22 +0200
Message-Id: <9702010912.AA26068@poveri.tekla.fi>
To: freebsd-hackers@FreeBSD.ORG
Subject: Re: Error Message (mounting a DOS partition)
Sender: owner-hackers@FreeBSD.ORG
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> > Error mounting /dev/wd1s2 on /DOS invalid argument 22

I also have a DOS partition I can't mount (not that I really care...)
There seems to be some sort of offset thingie going on that FreeBSD
doesn't know about.

I have three slices:
/dev/wd0s1 is DOS C: and can be mounted from FreeBSD.
/dev/wd0s2 is FreeBSD.
/dev/wd0s3 is DOS D: and can NOT be mounted from FreeBSD.

/dev/wd0s3 (aka D:) has NULs at the beginning where mountmsdosfs()
expects a boot sector.  However, there seems to be a DOS fs at an
offset of 0x7e00 bytes (go figure) from the beginning:

hexdump -C /dev/wd0s3 | head -12
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 01  |................|
000001c0  c1 9a 06 3f ff fd 3f 00  00 00 c1 26 06 00 00 00  |...?..?....&....|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa  |..............U.|
00000200  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00007e00  eb 3c 90 4d 53 44 4f 53  35 2e 30 00 02 08 01 00  |.<.MSDOS5.0.....|
00007e10  02 00 02 00 00 f8 c5 00  3f 00 40 00 3f 00 00 00  |........?.@.?...|
00007e20  c1 26 06 00 80 00 29 cf  1e 40 11 44 20 20 20 20  |.&....)..@.D    |

Here is fdisk output:

******* Working on device /dev/rwd0 *******
parameters extracted from in-core disklabel are:
cylinders=1023 heads=64 sectors/track=63 (4032 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=1023 heads=64 sectors/track=63 (4032 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 0 is:
sysid 6,(Primary 'big' DOS (> 32MB))
    start 63, size 104769 (51 Meg), flag 0
        beg: cyl 0/ sector 1/ head 1;
        end: cyl 25/ sector 63/ head 63
The data for partition 1 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
    start 104832, size 3612672 (1764 Meg), flag 80
        beg: cyl 26/ sector 1/ head 0;
        end: cyl 921/ sector 63/ head 63
The data for partition 2 is:
sysid 5,(Extended DOS)
    start 3717504, size 403200 (196 Meg), flag 0
        beg: cyl 922/ sector 1/ head 0;
        end: cyl 1021/ sector 63/ head 63
The data for partition 3 is:
<UNUSED>

									++sja