*BSD News Article 60833


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From: cau@cc.gatech.edu (Carlos Ugarte)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Install prob w/ 2.1R - cannot mount root on mixed IDE/SCSI
Date: 30 Jan 1996 00:24:05 -0500
Organization: College of Computing, Georgia Tech
Lines: 63
Message-ID: <4eka1l$m8k@oscar.cc.gatech.edu>
References: <4eggo7$cu@oscar.cc.gatech.edu> <4eh1ef$9nn@times.tfs.com>
NNTP-Posting-Host: oscar.cc.gatech.edu
NNTP-Posting-User: cau

julian@mailhub.tfs.com (Julian Elischer) writes:

[description of my problem booting on a SCSI w/ 2 IDEs skipped]

>I'm not sure if the '-a'  option works on the bootblocks
>if it does you shoulkd be able to use sd(2,a)/kernel and then use 
>sd0 when the kernel stops to ask about root disks..

Nope, don't think it did.  This is the first time I ever work
with FreeBSD (from an admin point of view), so I can't really
say, but it did not prompt me for the root filesystem.

>what you COULD do to get yourself up and going would be to
>disable (in the bios) your IDE drives, and use sd(0) as the
>boot response
>UNIX will still see the IDE drives but the BIOS won't
>you'll need to enable them before OS@ and DOS will see them again though.

This, on the other hand, worked great.  Previously, I had not even
been able to boot into it, but by disabling the IDEs in the BIOS
(and having installed a "normal" boot sector on the SCSI), it
booted into FreeBSD fine.

>probably you should (once you are up) look at
>/usr/src/sys/i386/bootblocks/biosboot/boot.c
>(and it's friends and try figure out the correct parameters to pass to the
>kernel as it's booting, compile them in by default
>and reinstall that new bootblock..)

And then I started poking around.  After quite a while, I discovered
that a one line change did the trick for me.  In the boot.c
mentioned above, there's a line with something like
"MAKEBOOTDEV(...)".  It turns out that one of the parameters it
was passing (the variable unit) changed values depending on
whether or not the IDEs were enabled in the BIOS.  If the IDEs
were disabled, unit=0.  If the IDEs were enabled, unit=1.  Once
again, this was with two IDEs and one SCSI (trying to boot off
the SCSI).  So hardcoding unit=0 (before MAKEBOOTDEV) did the
trick.  I guess it's getting confused (wd0, wd1, therefore it
must be sd2).  Then like you said, recompile and reinstall, and I
was set to go.  I can now boot off directly (IDEs disabled, boots
directly into FreeBSD) or from OS-BS, or from OS/2's Boot
Manager.

Incidentally, I tried changing it earlier (at the "Boot:"
prompt), but if I did it then, then the loader wouldn't find the
kernel if the IDEs were enabled (if they were disabled,
everything's great).  Thus for the first part, unit had to =2 (if
IDEs were enabled).

>I know what I want to do to fix it and you MIGHT have given me the excuse..
>I'll look at a fix this weekend.

Thanks for the help, Julian.  Hope the rest of my stay with
FreeBSD will be less troublesome :)

Carlos

-- 
Carlos A. Ugarte                                cau@cc.gatech.edu
Author of PageMage, a virtual desktop util for OS/2
http://www.cc.gatech.edu/people/home/cau/
Computer Science Senior at Georgia Tech