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From: barrett@lucy.ee.und.ac.za (Alan Barrett)
Newsgroups: comp.os.386bsd.questions
Subject: Re: NetBSD and DOS coexistence ?
Message-ID: <1t5kqp$mh4@lucy.ee.und.ac.za>
Date: 16 May 93 18:58:33 GMT
Article-I.D.: lucy.1t5kqp$mh4
References: <1993May15.164807.15131@alf.uib.no>
Organization: Elec. Eng., Univ. Natal, Durban, S. Africa
Lines: 67
NNTP-Posting-Host: lucy.ee.und.ac.za
In article <1993May15.164807.15131@alf.uib.no>,
tl@cmr.no (Tom Lislegaard) writes:
> I'm having problems installing NetBSD and DOS on the same disk, can
> anyone explain to me step by step how to do it so I can boot both systems
> alternately.
I have been unable to get NetBSD to work with its disk label anywhere
other than in the second physical sector. The docs suggest that one
should be able to set aside a partition with type 0xA5, and have NetBSD
keep its disk label in the second sector of that partition, but it
doesn't work for me. I did some reading of the sources and couldn't
immediately see what was wrong, but I have a suspicion that it might
have something to do with geometry translation in my IDE drive.
Anyway, I had some free space between the partition table (head 0
cylinder 0 sector 1) and the start of my DOS partition (head 1 cylinder
0 sector 1), so I was able to put the disk label in the physical second
sector by configuring my partition table as follows:
Partition 1: Bootable, Type = DOS, Start = (hd 1, cyl 0, sect 1),
end = (end of DOS partition)
Partition 2: Bootable, Type = 0xA4, start = (start of NetBSD partition),
end = (end of NetBSD partition)
Partition 3: Not bootable, Type = 0xA5, start = (hd 0, cyl 0, sect 1),
end = (last head, cyl 0, last sector)
Now, the code that wants the NetBSD disk label in the physical second
sector can find it there, the code that wants it in the second sector
of the partition with type 0xA5 can find it there, and the code that
might be confused by geometry translation (or whatever else was wrong)
appears to be pacified. Neither the fact that partitions 1 and 3
overlap nor the use of the bogus type 0xA4 for the true NetBSD
partition appears to do any harm.
> Pointers to good boot managers are also welcome, I picked up ``pboot'',
> but it sure doesn't work the way I'm setting up things.
I wrote my own, but it's not ready for public release. Some features:
* multiple simultaneous bootable partitions, with a menu to choose
between them.
* 12-character description for each partition.
* configurable timeout period before default menu choice is taken.
* optional ability to write selected menu choice to disk, where it
becomes the new default.
* boot flag in partition table overloaded to permit bootable partitions
elsewhere than on the first hard drive.
* press A or B from menu to boot from first or second floppy drive.
press C or D to boot from first or second hard drive.
press R to try booting ROM BASIC.
* All the above fits in the 512-byte partition sector. No 1-Meg
boot manager partitions for me, thanks.
> If someone is successfully running more than two systems off the same disk
> I'd be interrested in that too, it happens that I run NT or even OS/2.
Do you mean several systems off the same partition? Novell's LOADER
will allegedly do that. They haven't released the source code, but the
binaries are free. I am not sure, but the impression I got from the
docs was that you have to have exactly one bootable partition, and this
partition has to have a DOS file system; then LOADER gives you a menu
and you can boot off a DOS file that contains a binary sector image,
thereby booting an OS that lives in any partition.
--apb
Alan Barrett, Dept. of Electronic Eng., Univ. of Natal, Durban, South Africa
RFC822: barrett@ee.und.ac.za