From: Martin Harriss <martin@Princeton.EDU>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] dos boot record manglin'
Date: Thu, 3 Jul 2003 17:28:31 -0400 [thread overview]
Message-ID: <3F049FFF.5000204@Princeton.EDU> (raw)
In-Reply-To: <Pine.LNX.4.30.0307031533270.32598-100000@athena>
From the horses mouth:
http://www.microsoft.com/hwdev/download/hardware/fatgen103.pdf
Martin
Sam wrote:
> My laptop has three partitions: fat16, plan9, fat32.
> I recently copied a tarfile from /n/ftp to
> /n/c: to do some Windows work. I then halted
> kfs and powered down. I may have unmounted /n/c: --
> I can't be certain. It was later in the evening before
> I came back to actually do said work.
>
> Next boot, Windows didn't. Mounting the partition
> in plan 9 fails with "unknown format."
>
> It appears that something stepped on the dos boot record
> for both the fat16 and fat32 partitions. eg, fat16:
>
> term% dd -if /dev/sdC0/dos -bs 512 -count 1 | xd -c
> 1+0 records in
> 1+0 records out
> 0000000 13 00 00 00 d ff ff 18 00 00 06 00 9 P 2
> 0000010 0 0 0 00 00 f8 ff 00 ? 00 f0 00 ? 00 00 00
> 0000020 c1 c0 > 00 80 00 ) I k 05 a0 00 O N A
> 0000030 M E 00 F A T 1 6 3 c9
> <snip!> (everything after this looks OK)
>
> Note the peculiarly placed 9P2000 at byte 13.
>
> I'm trying to come up to speed on the fat filesystem
> format so I can re-establish the dos boot record fields
> that have been stamped on. Can anyone offer some
> help in this regard?
>
> For completeness, the dos boot record on the fat32
> partition looks like:
>
> term% dd -if /dev/sdC0/dos1 -bs 512 -count 1 | xd -c
> 1+0 records in
> 1+0 records out
> 0000000 13 00 00 00 d ff ff 18 00 00 06 00 9 P 2
> 0000010 0 0 0 00 00 f8 00 00 ? 00 f0 00 ? 00 00 00
> 0000020 f1 2 ~ 00 dc > 00 00 00 00 00 00 02 00 00 00
> 0000030 01 00 06 00 f6 f6 f6 f6 f6 f6 f6 f6 f6 f6 f6 f6
> 0000040 80 00 ) \t x c2 =
> 0000050 F A T 3 2 f6 f6 f6 f6 f6 f6
> <snip!>
>
> Cheers,
>
> Sam
>
>
prev parent reply other threads:[~2003-07-03 21:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-03 20:13 Sam
2003-07-03 21:28 ` Martin Harriss [this message]
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