*BSD News Article 21171


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Newsgroups: comp.os.386bsd.questions
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From: alm@netcom.com (Andrew Moore)
Subject: Re: FreeBSD - sio (com) and DOS HD problems
Message-ID: <almCDKxyy.8EC@netcom.com>
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
References: <1993Sep16.201358.26183@doug.cae.wisc.edu> <NEWSSERV!STARK!GENE.93Sep17075803@stark.uucp>
Date: Sun, 19 Sep 1993 02:37:45 GMT
Lines: 27

In article <NEWSSERV!STARK!GENE.93Sep17075803@stark.uucp> stark@cs.sunysb.edu writes:
>In article <1993Sep16.201358.26183@doug.cae.wisc.edu> tillemaj@cae.wisc.edu (John Edward Tillema) writes:
>
>	   2.  Is it possible to get info from a DOS hard disk partition
>	       to FreeBSD?  I tried creating a c device in mtools (2.0.7)
>	       but that didn't work, I also tried creating a disklabel
>	       (/dev/wd0h) for it (both are out of the FAQ), but again, that
>	       didn't work.  The changes I made were never present when I 
>	       would run disklabel again.  It would say unused partition h
>	       of size xxxx when I quit, then prompt if I wanted to overwrite
>	       DOS parition table.  Regardless of whether I answered y or n
>	       it didn't save the changes.  This is for a Conner 340 Meg IDE
>	       drive.

Does your disk have more than 1024 cylinders, by chance?  The correct
way to get DOS and FreeBSD to share a disk seems to be to use the DOS
geometry (i.e., <1024 cylinders) for both DOS and FreeBSD.  I know this
runs counter to conventional wisdom, but it works.

>So, I believe that if you expand the range of cylinders declared for the
>BSD c partition, so that they cover the DOS area, you will then be able
>also to define a new partition in the BSD disklabel that will allow you
>access to the DOS area.  But, this is not so easy as it might seem.

This is interesting, but a better solution is to simply use a different
geometry from the start.
-AM