From owner-freebsd-arch@FreeBSD.ORG Mon Aug 10 19:59:23 2009 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C66161065693; Mon, 10 Aug 2009 19:59:23 +0000 (UTC) (envelope-from mav@FreeBSD.org) Received: from cmail.optima.ua (cmail.optima.ua [195.248.191.121]) by mx1.freebsd.org (Postfix) with ESMTP id 1F7F28FC25; Mon, 10 Aug 2009 19:59:22 +0000 (UTC) Received: from [212.86.226.226] (account mav@alkar.net HELO mavbook.mavhome.dp.ua) by cmail.optima.ua (CommuniGate Pro SMTP 5.2.9) with ESMTPSA id 251192793; Mon, 10 Aug 2009 22:59:19 +0300 Message-ID: <4A807BDD.6040709@FreeBSD.org> Date: Mon, 10 Aug 2009 22:58:21 +0300 From: Alexander Motin User-Agent: Thunderbird 2.0.0.21 (X11/20090405) MIME-Version: 1.0 To: Warner Losh References: <200908101640.n7AGeYH0054650@fire.js.berklix.net> <86eirjbjl3.fsf@ds4.des.no> <20090810.125403.74653324.imp@bsdimp.com> In-Reply-To: <20090810.125403.74653324.imp@bsdimp.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: des@des.no, jhs@berklix.com, freebsd-hardware@freebsd.org, freebsd-arch@freebsd.org Subject: Re: Do we still need ATA disk CHS addressing? X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Aug 2009 19:59:27 -0000 Warner Losh wrote: > My question, and maybe I missed this earlier in the thread, is what's > the benefit to removing this support? How much code is saved? It is not about code size, but about code structurization. ATA(4) has too much cross-level relations, making it cryptic. I am trying to unroll some of them to simplify code. > Having said all that, I think it is OK, but I'd definitely poll the > pc98 guys first... Just to make sure they don't need it and re-fork > the ata driver to get it :) GEOM has no terms of cylinders/heads/sectors, in fact it works only with LBA. CHS translation is only needed for drives, that have no native LBA support. It is not about disk partitioning or label format. It is just a method to linearize nonlinear address space of ancient drives. For last 10 years, since drives lost their classic geometry, drives are doing this translation on firmware level. -- Alexander Motin