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Date: Mon, 25 Nov 1996 09:13:47 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199611242213.JAA05339@godzilla.zeta.org.au>
To: darrylo@sr.hp.com, rgrimes@GndRsh.aac.dev.com
Subject: Re: 2.2-ALPHA install failure
Cc: current@freefall.freebsd.org, jkh@time.cdrom.com
Sender: owner-current@FreeBSD.ORG
X-Loop: FreeBSD.org
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>>      How about the values of "historical_bogus_partition_table", as
>> given in sys/i386/isa/diskslice_machdep.c?
>> 
>> 	The data for partition 3 is: 
>> 	sysid 165,(FreeBSD/NetBSD/386BSD) 
>> 	    start 0, size 50000 (24 Meg), flag 80 
>> 	       beg: cyl 0/ sector 1/ head 0; 
>> 	       end: cyl 1023/ sector 63/ head 255 
>                                     ^^ bogus (ie this means 62 sectors!!)
>> 
>
>I would like to also see that corrected/changed to:
> 	The data for partition 3 is: 
> 	sysid 165,(FreeBSD/NetBSD/386BSD) 
> 	    start 0, size 2097152 (1024 Meg), flag 80 
> 	       beg: cyl 0/ sector 1/ head 0; 
> 	       end: cyl 1023/ sector 32/ head 63

This would not work so well.  The historical_bogus_partition_table works
perfectly with ncr and other geometry-detecting controllers _because_
it is perfectly invalid.  Your table is just as invalid for disks smaller
than 1GB and for non-SCSI disk [drivers] that can't handle either 255/63
or 64/32 geometries.

>Or atleast make size == cyl * sec * head  (ie 1024*64*255 == 16711680)
>my reasoning is that any third party fdisk program that sees the current
>bogus table likes to try and ``fix it'' and usually ends up doing quite
>the wrong thing : -(.

If you run a third party fdisk program on the disk, then the disk isn't
dedicated.

Bruce