Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965202AbVJVCz2 (ORCPT ); Fri, 21 Oct 2005 22:55:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932572AbVJVCz2 (ORCPT ); Fri, 21 Oct 2005 22:55:28 -0400 Received: from mail.dvmed.net ([216.237.124.58]:44217 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932137AbVJVCz1 (ORCPT ); Fri, 21 Oct 2005 22:55:27 -0400 Message-ID: <4359A9FE.4010503@pobox.com> Date: Fri, 21 Oct 2005 22:54:54 -0400 From: Jeff Garzik User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: dougg@torque.net CC: Matthew Wilcox , Luben Tuikov , Christoph Hellwig , andrew.patterson@hp.com, "Moore, Eric Dean" , jejb@steeleye.com, linux-scsi@vger.kernel.org, Linux Kernel , Linus Torvalds Subject: Re: ioctls, etc. (was Re: [PATCH 1/4] sas: add flag for locally attached PHYs) References: <91888D455306F94EBD4D168954A9457C048F0E34@nacos172.co.lsil.com> <20051020160155.GA14296@lst.de> <4357CB03.4020400@adaptec.com> <20051020170330.GA16458@lst.de> <4357F7DE.7050004@adaptec.com> <1129852879.30258.137.camel@bluto.andrew> <43583A53.2090904@pobox.com> <435929FD.4070304@adaptec.com> <20051021180455.GA6834@lst.de> <43592FA1.8000206@adaptec.com> <20051021182009.GA3364@parisc-linux.org> <4359A44B.3090804@torque.net> In-Reply-To: <4359A44B.3090804@torque.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: 0.0 (/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1301 Lines: 31 Douglas Gilbert wrote: > However, the block layer is used in the context of a > block device (and in some cases a char device). > If SAS domain discovery is done from the user space, and > the root file system is the far side of a SAS expander, > there are no suitable devices, just the SAS initiator > (HBA) which currently we cannot address via the block layer. Invalid example. All of the methods listed -- request_queue, netlink, chrdev, sysfs, ioctl -- will work just fine when the root filesystem is on the far side of a SAS expander. These are just methods of communication, nothing more. In your example -- userspace discovery required before root filesystem can be found -- a program running from initrd/initramfs would create an SMP device node, open it, and then proceed with the discovery and configuration process, which in turn creates the device nodes necessary to mount the root filesystem. A request_queue is just a queue. You are in complete control of who are the producer(s) of requests, and who are consumer(s). Jeff - 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/