From owner-svn-src-all@FreeBSD.ORG  Mon May 23 06:56:33 2011
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 933C3106564A;
	Mon, 23 May 2011 06:56:33 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
	by mx1.freebsd.org (Postfix) with ESMTP id 4BCDF8FC08;
	Mon, 23 May 2011 06:56:32 +0000 (UTC)
Received: from critter.freebsd.dk (critter.freebsd.dk [192.168.61.3])
	by phk.freebsd.dk (Postfix) with ESMTP id EDA005DC2;
	Mon, 23 May 2011 06:56:31 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
	by critter.freebsd.dk (8.14.4/8.14.4) with ESMTP id p4N6uUgA011295;
	Mon, 23 May 2011 06:56:30 GMT (envelope-from phk@critter.freebsd.dk)
To: "Andrey V. Elsukov" <ae@FreeBSD.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 23 May 2011 09:29:07 +0400."
	<4DD9F0A3.701@FreeBSD.org> 
Content-Type: text/plain; charset=ISO-8859-1
Date: Mon, 23 May 2011 06:56:30 +0000
Message-ID: <11294.1306133790@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: Adrian Chadd <adrian@FreeBSD.org>, src-committers@FreeBSD.org,
	svn-src-all@FreeBSD.org, Marcel Moolenaar <marcel@xcllnt.net>,
	Stefan Farfeleder <stefanf@FreeBSD.org>,
	svn-src-head@FreeBSD.org, Warner Losh <imp@bsdimp.com>
Subject: Re: svn commit: r221972 - head/sys/geom/part 
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 23 May 2011 06:56:33 -0000

In message <4DD9F0A3.701@FreeBSD.org>, "Andrey V. Elsukov" writes:

>There is another opinion:
>http://www.boot-us.com/gloss02.htm
>
>"There is the convention that partitions should always start and end on *=
>cylinder boundaries*."

It is actually more weird than that:

The rule is that the starting or ending head of one of the four
slices represent the number of heads used to access the drive, and
ditto for sectors.

This "requirement" dates back to "smart" BIOS'es and ST-506 drives
which couldn't ask the drive for its geometry.

It has been revived a couple of times, when people got creative
around the various silly sizes, most notably the 524MB "limit".

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.