Return to BSD News archive
Received: by minnie.vk1xwt.ampr.org with NNTP id AA1261 ; Tue, 23 Feb 93 14:32:42 EST Newsgroups: comp.unix.bsd Path: sserve!manuel.anu.edu.au!munnari.oz.au!metro!ipso!runxtsa!bde From: bde@runx.oz.au (Bruce Evans) Subject: Re: how do I undo 386BSD boot blocks? Message-ID: <1993Feb14.234255.6122@runx.oz.au> Organization: RUNX Un*x Timeshare. Sydney, Australia. References: <1993Feb12.010335.26398@jpl-devvax.jpl.nasa.gov> <1993Feb12.024645.20918@fcom.cc.utah.edu> <1993Feb12.184310.27616@jpl-devvax.jpl.nasa.gov> Date: Sun, 14 Feb 93 23:42:55 GMT Lines: 32 In article <1993Feb12.184310.27616@jpl-devvax.jpl.nasa.gov> kaleb@seaview (Kaleb Keithley) writes: >In article terry@cs.weber.edu (A Wizard of Earth C) writes: >> because I wrote >>>There are some poor assumptions about telling people to use 'fdisk /mbr'. >> >>There is an alternate method in INSTALL.NOTES. Basically, you don't need >>to fdisk the mbr for a valid one to be written -- you just have to invalidate >>it. This can be accomplished with either of the following: >> >> 1) low-level format the disk. > >Yeah, I could throw my 486 into the Pacific too! Get a grip Mr. Wizard of >... >> 2) boot dist.fs or fixit.fs and type dd if=/386bsd of=/dev/wd0a > >And where does that leave me? Do I still need a DOS disk after doing >that to fix up my now invalidated master boot record? I bet I do! The alternative methods are only good for wiping out a 386BSD that is using the whole disk. After wiping out the mbr, of course you have to write a new one somehow. I would just use "cat some-old-saved-boot-block >/dev/wdxx". There is no need to destroy the old boot block first, and under 386BSD destroying the old boot block would destroy the disk label, making it hard to write on the disk. If 386BSD is only on one partition, then it can be removed by deleting the partition. Unfortunately, 386BSD doesn't provide any way to delete its own partition, and many operating systems don't provide official ways to delete foreign partitions. But deleting partitions is trivial compared with creating them: just write 16 ASCII 0's over the partition table entry. -- Bruce Evans (bde@runx.oz.au)