From owner-freebsd-current@FreeBSD.ORG Mon Oct 1 09:46:34 2012 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DA459106564A; Mon, 1 Oct 2012 09:46:34 +0000 (UTC) (envelope-from root@free.fr) Received: from smtp5-g21.free.fr (smtp5-g21.free.fr [IPv6:2a01:e0c:1:1599::14]) by mx1.freebsd.org (Postfix) with ESMTP id BEA128FC14; Mon, 1 Oct 2012 09:46:32 +0000 (UTC) Received: from free.fr (unknown [82.235.65.2]) by smtp5-g21.free.fr (Postfix) with ESMTP id 45AEBD4815C; Mon, 1 Oct 2012 11:46:28 +0200 (CEST) To: "Andrey V. Elsukov" From: Raoul MEGELAS Date: Mon, 01 Oct 2012 11:46:27 +0200 Sender: root@free.fr Message-Id: <20121001094628.45AEBD4815C@smtp5-g21.free.fr> Cc: freebsd-current@freebsd.org Subject: Re: gpart on macbook air X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Oct 2012 09:46:35 -0000 On Mon, 01 Oct 2012 12:29:02 +0400 From: "Andrey V. Elsukov" wrote: On 30.09.2012 23:06, Raoul MEGELAS wrote: >>> When you are deleting a partition, the kernel completely overwrites the >>> partition table and PMBR area. You can compare first 34 blocks before >>> deletion and after to see what is going on. >> >> I can understand that, but i would have thought >> that the deletion of the concerned partition was written preserving others??? >> >> something like: >> >> - read the gpt table >> - find the offset >> - zeroes the partition entry >> - rewrites the table? >> >> is not that logic? >> >> if it is not so, i does not understand this behaviour. > Hi, Raoul, > > The kernel has a copy of the partition table in the memory. > When you are deleting some partition, it removes the partition entry > from the memory, constructs updated GPT header and table, calculates > checksums and writes this data into corresponding places. > Any way, this should correctly work. > > My guess is that Apple's boot loader detects some changes and > just doesn't want to work. If you think that gpart incorrectly works, > please make a copy of first 34 blocks before and after deletion and > send them to me. Hi Andrey, thanks for your clear explaination; that make sense. in all case i will backup my 18g freebsd partition and and delete it. as soon as possible will send privately the two copy of the first 34 blocks of the disk, before and after deletion. Thanks again. Raoul rmgls@free.fr