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To: Benjamin Kaduk <kaduk@MIT.EDU>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 24 Oct 2011 21:18:57 -0400."
	<alpine.GSO.1.10.1110242118020.882@multics.mit.edu>
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Date: Tue, 25 Oct 2011 06:08:14 +0000
Message-ID: <67820.1319522894@critter.freebsd.dk>
Cc: "Andrey V. Elsukov" <bu7cher@yandex.ru>, freebsd-current@freebsd.org
Subject: Re: aliasing (or renaming) kern.geom.debugflags
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In message <alpine.GSO.1.10.1110242118020.882@multics.mit.edu>, Benjamin Kaduk 
writes:
>On Mon, 24 Oct 2011, Andrey V. Elsukov wrote:

>> This is stale message. boot0cfg might work without this.
>
>On a *mounted* disk? Surely that qualifies as an "open" for the purposes 
>of the check.

The way this used to work before gpart, is that boot0cfg would send
a GEOM ctl-message to the MBR-geom asking "Would you please write this
boot code ?"

Since the MBR-geom was the "owner" of the whole disk, and the one
who had it open for writing, it could obviously do so, if  it saw fit,
and after it had edited its idea about the mbr-partition table into
that boot-code.

Gpart appearantly does not implement such a ctl message.

-- 
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.