Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932223AbVJQJ0Y (ORCPT ); Mon, 17 Oct 2005 05:26:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932221AbVJQJ0X (ORCPT ); Mon, 17 Oct 2005 05:26:23 -0400 Received: from styx.suse.cz ([82.119.242.94]:50601 "EHLO mail.suse.cz") by vger.kernel.org with ESMTP id S932223AbVJQJ0X (ORCPT ); Mon, 17 Oct 2005 05:26:23 -0400 Date: Mon, 17 Oct 2005 11:26:21 +0200 From: Vojtech Pavlik To: Kay Sievers Cc: dtor_core@ameritech.net, Greg KH , Hannes Reinecke , Patrick Mochel , airlied@linux.ie, linux-kernel@vger.kernel.org, Adam Belay Subject: Re: [patch 0/8] Nesting class_device patches that actually work Message-ID: <20051017092621.GA10522@ucw.cz> References: <20051013020844.GA31732@kroah.com> <20051013105826.GA11155@vrfy.org> <20051014084554.GA19445@vrfy.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051014084554.GA19445@vrfy.org> X-Bounce-Cookie: It's a lemon tree, dear Watson! User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2337 Lines: 52 On Fri, Oct 14, 2005 at 10:45:54AM +0200, Kay Sievers wrote: > Sure, than that physical (while that distinction is silly by itself) > will just have several child devices. Look at the mouse0 and event0 in > the ascii drawing. > > That solution would keep a better device separation, sure. But it is > completely incompatible with everything we ever had in sysfs and > nobody wants to rewrite _all_ userspace programs. > > It invents artificial subclass names below a "master" class, which is > absolutely not needed. > > It creates the magic "interfaces" directory, which is confusing, cause > it classifies devices by itself. > > It doesn't represent any relationship and hierarchy of devices and > adding a forest of magic symlinks and "device" pointers is a very bad > design. The proposed "inter-class" symlinks make it even harder to > understand sysfs as it already is. > > The biggest problem with current sysfs is that the driver hacker has > to decide if the device is "hardware" or "virtual" which in a lot of > cases just can't tell and this distiction doesn't make any sense > today. > > All the more complex subsystems use "virtual buses" and an unconnected > bunch of class-devices to model its sysfs represention, which is just > to work around a major design flaw in sysfs! We really should get > _one_ device tree with its natural hierarchy, get rid of the stupid > "device"-link, the PHYSDEVPATH and the unconnected class devices. > Every device should just carry its dependency tree in it _own_ > devpath! > > I'm very sure, we want a unified tree in /sys/devices, regardless of > the type of device, to represent the global hierarchy wich is exactly > what you want to know from a device tree! That way we stack "virtual" > _and_ "physical" in a sane manner and at the same time get very clean > class interfaces. We would stop to mix up "hierarchy" and "classes" > all over the tree. Let me just say: I completely agree here. The hard distinction between 'real' and 'virtual' devices causes more problems than it solves. -- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/