From owner-freebsd-hackers@FreeBSD.ORG Mon Mar 13 16:20:30 2006 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 17E8716A4C6 for ; Mon, 13 Mar 2006 16:20:28 +0000 (UTC) (envelope-from imp@bsdimp.com) Received: from harmony.bsdimp.com (vc4-2-0-87.dsl.netrack.net [199.45.160.85]) by mx1.FreeBSD.org (Postfix) with ESMTP id 63EBB43D48 for ; Mon, 13 Mar 2006 16:20:27 +0000 (GMT) (envelope-from imp@bsdimp.com) Received: from localhost (localhost.village.org [127.0.0.1] (may be forged)) by harmony.bsdimp.com (8.13.3/8.13.3) with ESMTP id k2DGJ6jN076714; Mon, 13 Mar 2006 09:19:09 -0700 (MST) (envelope-from imp@bsdimp.com) Date: Mon, 13 Mar 2006 09:19:23 -0700 (MST) Message-Id: <20060313.091923.48529658.imp@bsdimp.com> To: darren.pilgrim@bitfreak.org From: "M. Warner Losh" In-Reply-To: <44138F0A.8000606@bitfreak.org> References: <44138F0A.8000606@bitfreak.org> X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0 (harmony.bsdimp.com [127.0.0.1]); Mon, 13 Mar 2006 09:19:09 -0700 (MST) Cc: freebsd-hackers@freebsd.org Subject: Re: Why do we have the orm device? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Mar 2006 16:20:30 -0000 In message: <44138F0A.8000606@bitfreak.org> Darren Pilgrim writes: : I see it on all of my machines and have never seen it used by anything. : The orm(4) man page says it's part of ISA bus support and is designed : to claim ROMs sitting in the memory address space, but doesn't go into : any detail why it's necessary to prevent other drivers from using ROM : addresses. : : So why do we have this device? The ROMs that sit on the ISA bus in expansion cards and as part of video support cannot be used for other purposes. orm prevents that by allocating those resources. This prevents collisions with old ISA devices like 16-bit PC Card bridges, many network cards that have shared memory, as well as some scsi cards that also do the same. Many of these ISA devices have the ability to set which address range to use. If there's a ROM where the driver picks, then it just won't work. You can't have two devices decode the same address. Warner