From owner-freebsd-arch@FreeBSD.ORG Fri Sep 12 01:05:20 2003 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 96A3416A4BF; Fri, 12 Sep 2003 01:05:20 -0700 (PDT) Received: from herring.nlsystems.com (mailgate.nlsystems.com [80.177.232.242]) by mx1.FreeBSD.org (Postfix) with ESMTP id 185AA43FF2; Fri, 12 Sep 2003 01:05:19 -0700 (PDT) (envelope-from dfr@nlsystems.com) Received: from [10.0.0.2] (herring.nlsystems.com [10.0.0.2]) by herring.nlsystems.com (8.12.9/8.12.8) with ESMTP id h8C84egs008780; Fri, 12 Sep 2003 09:04:40 +0100 (BST) (envelope-from dfr@nlsystems.com) From: Doug Rabson To: "M. Warner Losh" In-Reply-To: <20030912.013911.13774129.imp@bsdimp.com> References: <20030911.153929.44983352.imp@bsdimp.com> <20030912.013911.13774129.imp@bsdimp.com> Content-Type: text/plain Message-Id: <1063353880.5536.6.camel@herring.nlsystems.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.0 Date: 12 Sep 2003 09:04:40 +0100 Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=-4.9 required=5.0 tests=EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, REPLY_WITH_QUOTES,USER_AGENT_XIMIAN version=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) cc: arch@freebsd.org Subject: Re: When to burn those bridges X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Sep 2003 08:05:20 -0000 On Fri, 2003-09-12 at 08:39, M. Warner Losh wrote: > In message: > John Baldwin writes: > : How do you know which drivers to detach? Are you going to detach > : the generic PCI ATA driver on every kldload? Are you going to > : detach the generic PCI-PCI bridge driver for PCI-PCI bridges on > : add-on cards for every kldload of a PCI driver? That would be > : freaking insane. The problem is that you don't know what devices > : a new driver might be more suitable for than existing drivers. > > This does suck. > > : > Besides, proble routines on self enumerating devices should look at > : > the IDs that anybody can look at at any time. However, there are some > : > issues with some drivers that have old/new versions or that need to > : > ask the hardware what kind of thing it really is before making the > : > call. These drivers are rare, thankfully, and even rarer are those > : > that have different levels. owi/wi is the only one I know of that > : > fits this bill, and the only reason owi is there is to help fix wi, so > : > I don't think we should necessarily design to make this sort of thing > : > too easy.... > : > : rl(4) and re(4)? Several drivers still allocate resources in probe(), > : which would break things. > > yea, but that's a bit of a pathological case. first, rl/re attach to > a specific driver, and not override. So maybe we could mandate that > drivers that are generic and return negative return values should be > constrained to only look at the plug and play info and are not allowed > to look at resources. owi/wi is the only pair that does this > evilness. This is why I was thinking about a device flag which a driver would set if it is just a placeholder which can be pre-empted safely.