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From: jpl@allegra.UUCP (John P. Linderman)
Newsgroups: net.bugs.4bsd
Subject: Re: /etc/diskpart
Message-ID: <3821@allegra.UUCP>
Date: Thu, 25-Apr-85 08:42:36 EST
Article-I.D.: allegra.3821
Posted: Thu Apr 25 08:42:36 1985
Date-Received: Fri, 26-Apr-85 05:35:30 EST
References: <3679@allegra.UUCP> <355@mtxinu.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 28

>  The first line of diskpart(8) reads "Diskpart is used to calculate the disk
>  partition sizes based on the default rules used at Berkeley."  It's
>  intended use is to generate the first cut at both the disktab and
>  kernel driver entries, not to *report* the state of either.

And the second line reads ``If the -p option is supplied, tables suitable
for inclusion in a device driver are produced.''  My interpretation of
``suitable'' would include a reasonably close relationship between the
contents of /etc/disktab [which, while we are quoting chapter and verse,
``describes disk geometries and disk partition characteristics,''] and the
kernel code that supports the device.  While I agree with the comment in
disktab(5) that the proper place for the information is on each pack,
we aren't there yet.  Where we are has newfs reading all the entries in
disktab, diskpart reading some of them, and the kernel code reading none
of them, with conspicuous opportunities for disaster.

I don't know what the ``intended use'' of diskpart is, but anyone wishing
to see what newfs is really going to do, or anyone wishing to generate
device driver tables to support a new drive or a new partitioning of an
old drive, has a use for a utility that looks carefully at the contents
of /etc/disktab.  There is good reason to make this the same utility that
understands the default rules, because one would like to do something
intelligent (or at least consistent) if partition size information is
left unspecified.  So I ``fixed'' diskpart by adding an option to meet
those needs.  I suppose it is impossible to introduce any change
whatsoever without offending someone's sense of aesthetics.

John P. Linderman  Department of diskpart deportment  allegra!jpl