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Date:      Sat, 25 Jul 2009 00:14:17 -0400 (EDT)
From:      "M. Warner Losh" <imp@bsdimp.com>
To:        scottl@samsco.org
Cc:        svn-src-head@FreeBSD.org, mav@FreeBSD.org, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, cperciva@FreeBSD.org
Subject:   Re: svn commit: r195817 - head/usr.sbin/sysinstall
Message-ID:  <20090725.001417.-1417608789.imp@bsdimp.com>
In-Reply-To: <4A6A855C.7090003@samsco.org>
References:  <4A6A7F2D.90807@samsco.org> <20090724.235420.319856209.imp@bsdimp.com> <4A6A855C.7090003@samsco.org>

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In message: <4A6A855C.7090003@samsco.org>
            Scott Long <scottl@samsco.org> writes:
: M. Warner Losh wrote:
: > In message: <4A6A7F2D.90807@samsco.org>
: >             Scott Long <scottl@samsco.org> writes:
: > : M. Warner Losh wrote:
: > : > In message: <4A68DA56.60301@samsco.org>
: > : >             Scott Long <scottl@samsco.org> writes:
: > : > : M. Warner Losh wrote:
: > : > : > In message: <4A66D0F4.4030108@FreeBSD.org>
: > : > : >             Alexander Motin <mav@FreeBSD.org> writes:
: > : > : > : Colin Percival wrote:
: > : > : > : > Author: cperciva
: > : > : > : > Date: Wed Jul 22 03:50:54 2009
: > : > : > : > New Revision: 195817
: > : > : > : > URL: http://svn.freebsd.org/changeset/base/195817
: > : > : > : > 
: > : > : > : > Log:
: > : > : > : >   Remove the "dedicated disk mode" partitioning option from sysinstall, in
: > : > : > : >   both the disk partitioning screen (the 'F' key) and via install.cfg (the
: > : > : > : >   VAR_DEDICATED_DISK option).  This functionality is currently broken in 8.x
: > : > : > : >   due to libdisk and geom generating different partition names; this commit
: > : > : > : >   merely acts to help steer users away from the breakage.
: > : > : > : >   
: > : > : > : >   Submitted by:	randi
: > : > : > : >   Approved by:	re (kensmith)
: > : > : > : > 
: > : > : > : > Modified:
: > : > : > : >   head/usr.sbin/sysinstall/disks.c
: > : > : > : 
: > : > : > : Is there any other way to not align FS block to the ugly legacy 63
: > : > : > : sectors per track boundary with sysinstall now? I think RAIDs won't be
: > : > : > : happy. May be it would be better to fix it?
: > : > : > 
: > : > : > The reason we do it like this is because the boot blocks occupy the
: > : > : > first cylinder group.  Which with today's fake goemetry is 63
: > : > : > blocks...
: > : > : > 
: > : > : 
: > : > : I already covered this.  Unfortunately, Randi didn't take my bait. 
: > : > : Anyways, '63' is a minimum, it's not a singular value.  It's also
: > : > : an incredibly bad default.
: > : > 
: > : > Yes.  256 is just as good as 63, unless the geometry reports more than
: > : > 256 heads, which I don't think is possible...
: > : > 
: > : > Warner
: > : 
: > : If there is a BIOS in existence that can't find sector 256, then it 
: > : likely can't boot off of anything other than partition 1 in the fdisk
: > : table.  I bet that bugs like that were likely caught 15-20 years ago.
: > 
: > I think you were missing the point I was trying to make, I must have
: > been unclear.
: > 
: > If there were more than 256 sectors in the first cylinder, then
: > starting at 256 would overlap.  This is largely a theoretical
: > problem, I think, since I don't think that the BIOS can report a
: > geometry > 64.
: > 
: > The only issue that I can think of is that FreeBSD's fdisk wants to
: > have things on cylinder boundaries, which 256 isn't, so fdisk will
: > bitch and moan...
: > 
: > Warner
: 
: Ah, we will never be freed of the CHS bonds, will we.  Oh well.

Well, we could make it not bitch, except in extra picky mode :)

Warner



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