From owner-freebsd-current@FreeBSD.ORG Tue Jan 25 15:23:06 2005 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6D85716A4CE for ; Tue, 25 Jan 2005 15:23:06 +0000 (GMT) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 08B7C43D49 for ; Tue, 25 Jan 2005 15:23:06 +0000 (GMT) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.13.1/8.13.1) with ESMTP id j0PFMcIj004237; Tue, 25 Jan 2005 10:22:38 -0500 (EST) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)j0PFMcmB004234; Tue, 25 Jan 2005 15:22:38 GMT (envelope-from robert@fledge.watson.org) Date: Tue, 25 Jan 2005 15:22:37 +0000 (GMT) From: Robert Watson X-Sender: robert@fledge.watson.org To: "M. Warner Losh" In-Reply-To: <20050125.080053.29499868.imp@bsdimp.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: current@freebsd.org cc: pete@altadena.net Subject: Re: Devd event from GEOM? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 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: Tue, 25 Jan 2005 15:23:06 -0000 On Tue, 25 Jan 2005, M. Warner Losh wrote: > In message: <1106663905.35846.10.camel@shumai.marcuscom.com> > Joe Marcus Clarke writes: > : And how would I map those devices to a bus? Speaking with Linux HAL in > : mind, I would like to see storage devices added to devinfo. It would be > : great, IMHO, to see da0 attached to uhub2 on usb2 on ehci2 when walking > : devinfo. > > That's part of the problem. CAM doesn't use newbus attachments. IT > should. For physical devices, it appears there isn't much argument against newbus attachments, other than someone implementing it -- since this isn't really my area, I'll leave that discussion (and ideally, coding :-) for someone else. The interesting question becomes how you map between levels of abstraction: many consumers of device event information don't really care about the device and the route by which messages get to it from the CPU. They care about the abstraction layered over the device, and the events that occur in relating one object in an abstraction to another object, perhaps involving topologies that have little to do with the physical device topology. This raise the questions as to whether the newbus topology is really the most useful place to expose information like GEOM slicing, volume management of disk devices, and ethernet bonding for devices that may be physically discovered using newbus. And even if we can shove all the available object topologies into newbus, we'd also start bumping into how to represent all the interesting event types in newbus. One appealing thing to the current devd protocol design is that different abstraction layers (classes) can define their own event name spaces, and each abstraction layer can declare the events it knows about. newbus announces "I found a route to a physical device", GEOM shouts "And I found some storage space on it", etc. Robert N M Watson