*BSD News Article 6450


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Path: sserve!manuel.anu.edu.au!munnari.oz.au!sgiblab!spool.mu.edu!sol.ctr.columbia.edu!eff!world!ksr!dean
From: dean@ksr.com (Dean Anderson)
Newsgroups: comp.unix.bsd
Subject: Re: HELP: wiped out my DOS partition
Message-ID: <16808@ksr.com>
Date: 12 Oct 92 19:28:01 EDT
References: <1992Oct5.150129.27179@unibi.uni-bielefeld.de> <1apomrINNi8c@uwm.edu>
Sender: news@ksr.com
Organization: Kendall Square Research
Lines: 41

>  ha ha ha ha ha ha..  You did the same thing I did!!!
>
>   The "d" partition cann't be used as a partition ..  the 'd'
>partition is the whole drive..  So even though you set it aside as 70meg
>for unix. It actually was the first 70meg of your HD.  Which is probably
>where you dos is..

This shouldn't happen.  The driver should look at the disk label and the
partition table to determine the drive geometry.  A bit of effort has gone
into developing a common interface (the disklabel, /etc/disktab, and 
disklabel & diskpart commands) to avoid just these pitfalls.

This just demonstrates that the device driver writer is really in control
of the operating system. ;-)

I am particularly disappointed with the changes to ufs_disksubr.c for 
dos partitions.  This is supposed to be a machine independent file
for use by drivers. (someone correct me if I am wrong)

The PC BSD's should look at the dos partition table and create multiple
logical disk drives, one for each partition.

This has the following benefits:

1. Doesn't change machine independent code.  This makes it easier to
integrate future changes to BSD code, and contribute changes back to
Berkeley.

2. Makes it possible to mount Dos "drives".  A dos vfs is needed.

3. Makes it possible to ignore that dos exists and use the whole drive
without a dos partition table.  This is particularly attractive is you
have a large disk,  because dos will not work happilly with disks of
greater than 1024 cylinders without a lot of egregious hacking which
ultimately hurts ufs performance.

		--Dean
--
Dean Anderson			dean@ksr.com  |  I'm not voting because the
KSR Computing Facilities                      |  lack of a candidate has
Kendall Square Research                       |  co-opted me out of the process