Date: Fri, 24 Jul 2009 23:54:20 -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: <20090724.235420.319856209.imp@bsdimp.com> In-Reply-To: <4A6A7F2D.90807@samsco.org> References: <4A68DA56.60301@samsco.org> <20090724.233458.1683324074.imp@bsdimp.com> <4A6A7F2D.90807@samsco.org>
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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
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