From owner-freebsd-current@FreeBSD.ORG Fri Aug 15 11:22:40 2003 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 A655337B401 for ; Fri, 15 Aug 2003 11:22:40 -0700 (PDT) Received: from harmony.village.org (rover.bsdimp.com [204.144.255.66]) by mx1.FreeBSD.org (Postfix) with ESMTP id D3DF143F93 for ; Fri, 15 Aug 2003 11:22:39 -0700 (PDT) (envelope-from imp@bsdimp.com) Received: from localhost (warner@rover2.village.org [10.0.0.1]) by harmony.village.org (8.12.9/8.12.3) with ESMTP id h7FIMSFL030186; Fri, 15 Aug 2003 12:22:28 -0600 (MDT) (envelope-from imp@bsdimp.com) Date: Fri, 15 Aug 2003 12:25:18 -0600 (MDT) Message-Id: <20030815.122518.05878262.imp@bsdimp.com> To: eaja@erols.com From: "M. Warner Losh" In-Reply-To: <20030815111809.06960905.eaja@erols.com> References: <20030814110113.4d238ddd.eaja@erols.com> <20030814173807.GR10708@funkthat.com> <20030815111809.06960905.eaja@erols.com> X-Mailer: Mew version 2.2 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit cc: freebsd-current@freebsd.org cc: gurney_j@efn.org Subject: Re: usbd does not use detach 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: Fri, 15 Aug 2003 18:22:40 -0000 In message: <20030815111809.06960905.eaja@erols.com> Eric Jacobs writes: : On Thu, 14 Aug 2003 10:38:07 -0700 : John-Mark Gurney wrote: : : > : > This is a bit more complex than this. There are many more layers between : > usb and VFS. For USB umass devices, they proxy to cam, which then is an : > interface to da which is a provider for geom which then provides the : > final device for ufs to mount. So, each and every one of those steps : > need to be taught about this. Right now, very few things use newbus : > even though they should. This is a problem of them existing before : > newbus was nailed down. CAM doesn't use newbus for any of it's device : > management (scsi device, not HBA attachment). : : Yes, I'm aware that there are more layers. Propogating the flag value : down is trivial. The major deficiency of CAM and GEOM is that errors : can't be sent back up. For example, we have this scenario: : : # mount /dev/da0s1a /mnt # mounting a USB hard drive : # cd /mnt # in use : # kldunload umass # oops! it succeeds : # : : Ideally, I'd love to see an enhanced newbus provide the One True : Framework for attaching and detaching both devices and device : clients. Unfortunately, it seems like it would take a substantial : redesign to get there from this point. Nah, just to make cam use it. cam and newbus were contemporary developments, so cam used the old ad-hoc way of dealing. Warner