Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756882Ab0KSVTR (ORCPT ); Fri, 19 Nov 2010 16:19:17 -0500 Received: from kroah.org ([198.145.64.141]:57725 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755648Ab0KSVTL (ORCPT ); Fri, 19 Nov 2010 16:19:11 -0500 Date: Fri, 19 Nov 2010 13:16:49 -0800 From: Greg KH To: Vladislav Bolkhovitin Cc: Dmitry Torokhov , Richard Williams , Bart Van Assche , Boaz Harrosh , FUJITA Tomonori , Mike Christie , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , James Bottomley , scst-devel , Hannes Reinecke , Andy Yan , Andrew Morton , Vu Pham , Linus Torvalds , Joel Becker Subject: Re: [Scst-devel] [PATCH 8/19]: SCST SYSFS interface implementation Message-ID: <20101119211649.GA28606@kroah.com> References: <20101115161620.GB5981@kroah.com> <4CE16B8E.1000300@panasas.com> <8985DEAF-4227-4629-B90A-938D2BA3534E@etechsoft.com> <4CE2846C.6070501@vlnb.net> <4CE59482.3050002@gmail.com> <20101118214619.GA29097@kroah.com> <4CE6BB4A.5060606@gmail.com> <20101119202202.GB6323@core.coreip.homeip.net> <4CE6E323.8080703@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CE6E323.8080703@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2114 Lines: 49 On Fri, Nov 19, 2010 at 11:50:43PM +0300, Vladislav Bolkhovitin wrote: > Dmitry Torokhov, on 11/19/2010 11:22 PM wrote: > >> None of the SCST objects are Linux devices. None of them has entries in > >> /dev, none of them needs to send any events to udev and none of them > >> sends or receives data from DMA, hence has any DMA parameters or > >> restrictions. So, how can them fit into the driver/bus/device model you > >> are enforcing? > > > > Note that the entities in /sys/devices/... tree and not necessarily > > physical devices bit rather interface abstractionss. Consider, for > > example, /sys/class/input/*. None of the "devices" there talk directly > > to hardware, do DMA or other things. Some of them don't even talk to > > usrespace directly but rather through additional interfaces (evdev. > > mousedev, ect). Still they are represented there and even have suspend > > and resume methods (because even for logical devices it makes sense to > > save and restore some state). This is correct. > SCST devices are not even logical devices. As I wrote, "devices" word is > misleading. SCST devices are converse of what Linux means under this > word. SCST devices are like NFS exports: a place where those events > generated and those requests received. No, that's fine. > Think of SCST device as if it sits on the opposite side of the PCI bus > of the corresponding SCSI device Linux sees in /sys/class and /sys/bus. Again, that's fine, look at usb gadgets, it's the same thing. > So, if we need Linux devices for SCST devices, we create them using > scst_local driver. And then, of course, all them have their place in > /sys/class/ and /sys/bus. No, just /sys/bus/ which will cause them to become part of the big device tree in /sys/devices/ Again, use this interface, it is what it is there for, to not use it is just wrong. good luck, greg k-h -- 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/