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From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
Message-Id: <199603101326.FAA11063@GndRsh.aac.dev.com>
Subject: Re: booting from sd5 when wd3 is also installed
To: bde@zeta.org.au (Bruce Evans)
Date: Sun, 10 Mar 1996 05:26:16 -0800 (PST)
Cc: current@freebsd.org
In-Reply-To: <199603100915.UAA20728@godzilla.zeta.org.au> from "Bruce Evans" at Mar 10, 96 08:15:55 pm
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> 
> These changes should allow specifying the BIOS drive number independently
> of the FreeBSD unit number.  E.g., `9:sd(5,a)' describes the drive with
> BIOS drive number 9 and sd unit number 5.
> 
> hd(N,a) is no longer supported because it doesn't fit and it only works
> for unit number 0.  Use N:sd(0,a) instead.

YEAAA!!!  I love this, and would have killed for it 2 years ago, but now
the last 2 of my IDE drives sit on a shelf as junk....

> I haven't decided exactly how to handle these points:
> - how sticky should the drive number be?  What is the default drive number
>   after 1:sd(0,a)/nonesuch followed by /kernel?

IMHO, 0.  Does ``1:?'' or even ``1:xx(y,z)/kernel?'' work?

> - option BOOT_HD_BIAS.  This replaces option BOOT_HD.  The BIOS drive
>   number for unit N is currently BOOT_HD_BIAS + N.  Should the bias only
>   be added for sd drives?  How does biasing interact with previously
>   specified drive numbers?

I am not sure, I need to think on this one for a few days...

> 
> Please test the changes on systems with mixed IDE and SCSI drives.  I
> don't have any.

I can't test them, but have a small nit I found doing a visual over the
context diff.... ohh... and can you bounds check the BIOS drive number
against the number of drives reported by the BIOS, I seem to recall
an infinite error loop if you did something like wd(1,a)/kernel with
only one BIOS drive.

> 
> diff -c2 src/sys/i386/boot/biosboot/README.serial~ src/sys/i386/boot/biosboot/README.serial
> *** src/sys/i386/boot/biosboot/README.serial~	Fri Apr 21 19:43:53 1995
> --- src/sys/i386/boot/biosboot/README.serial	Sun Mar 10 18:08:25 1996
> ***************
> *** 77,83 ****
>   
>     >> FreeBSD BOOT @ 0x10000: 640/7168 k of memory
> !   Use hd(1,a)/kernel to boot sd0 when wd0 is also installed.
> !   Usage: [[[fd(0,a)]/kernel][-s][-r][-a][-c][-d][-b][-v][-h]]
> !   Use ? for file list or simply press Return for defaults
>     Boot:
>   
> --- 77,83 ----
>   
>     >> FreeBSD BOOT @ 0x10000: 640/7168 k of memory
> !   Usage: [[[0:][fd](0,a)]/kernel][-abcCdhrsv]
> !   Use 1:sd(0,a)kernel to boot sd0 if it is BIOS drive 1
> !   Use ? for file list or press ENter for defaults
                                    ^n

>     Boot:
>   


-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                 Reliable computers for FreeBSD