From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <200006141919.PAA01946@smtp2.fas.harvard.edu> To: 9fans@cse.psu.edu Subject: Re: [9fans] Plan 9 boot block question From: "Russ Cox" Date: Wed, 14 Jun 2000 15:16:04 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Topicbox-Message-UUID: bd6dc6c4-eac8-11e9-9e20-41e7f4b1d025 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