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From: "Russ Cox" <rsc@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Plan 9 boot block question
Date: Wed, 14 Jun 2000 15:16:04 -0400	[thread overview]
Message-ID: <200006141919.PAA01946@smtp2.fas.harvard.edu> (raw)

The first sector of the Plan 9 partition
contains both the beginning of the 9fat
partition (a BIOS parameter block (BPB))
and the partition boot sector (PBS).
The PBS begins with a three-byte intel
jump instruction that jumps over the BPB
to address 0x3E, which is where the PBS
code really starts.

The files /386/pbs and /386/pbslba have
bytes 0x03-0x03D (inclusive) zeroed; disk/format
takes care of writing the BPB when formatting
the disk, and can be used to install a new PBS
without hurting the extant BPB.

Saving the single 512-byte sector at the
beginning of your Plan 9 partition and then
restoring it should have been enough to
get you back up and running.

Russ



             reply	other threads:[~2000-06-14 19:16 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-06-14 19:16 Russ Cox [this message]
  -- strict thread matches above, loose matches on Subject: below --
2000-06-14 19:05 Jean Mehat

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