From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] minimal SAS transport class Date: Fri, 26 Aug 2005 21:53:54 -0400 Message-ID: <430FC7B2.7080700@pobox.com> References: <9BB4DECD4CFE6D43AA8EA8D768ED51C21D7A4B@xbl3.ma.emulex.com> <430B5CDB.9070204@s5r6.in-berlin.de> <430BB91F.7000406@vger.kernel.org> <20050824091230.GB26447@infradead.org> <430F398A.30200@adaptec.com> <430F6C56.1090801@pobox.com> <430F710E.7020206@adaptec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.dvmed.net ([216.237.124.58]:14508 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S965202AbVH0ByA (ORCPT ); Fri, 26 Aug 2005 21:54:00 -0400 In-Reply-To: <430F710E.7020206@adaptec.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Luben Tuikov Cc: Christoph Hellwig , linux-scsi@vger.kernel.org, Stefan Richter Luben Tuikov wrote: > On 08/26/05 15:24, Jeff Garzik wrote: > >>Luben Tuikov wrote: >> >> >>>Even simpler: the transport layer, calls SCSI Core, saying: "Hey here is >>>a pointer to struct scsi_domain_device. If you want, you an send REPORT >>>LUNS and other things to it." >> >> >>For the SG_IO ioctl, /dev/sg and request_queue usage, SCSI core must map >>an address (currently HCIL) into a scsi_domain_device pointer. These > > > The request queue is associated with the LU, not the scsi_domain_device. > When SCSI Core discovers the LU, it sets up the request queue for it, > etc. Again this is the role of SCSI Core, not messing up with transport > specific stuff. > > >>upper layer kernel elements rely on this "SCSI address", and rely on the >>fact that SCSI core can route from a block device straight to a SCSI >>LLD, using nothing more than this "SCSI address." > > > I don't get this. More basically... An in-kernel C pointer, to a SCSI target device, is not sufficient in all cases to address a target. This plays out most often in userland interfaces such as ioctls. >>That is the heart of the routing/addressing that the SCSI core must perform. > > > Disagree: now: scsi_device <--> request_queue, then: struct LU <--> request_queue. > > The LU points to the domain_device (as its parent). The domain_device > has a void *lldd_dev in it. The current SCSI code largely already has this stuff. >>Right now the addressing is hardcoded to HCIL. But that can be >>changed... One proposal was to use (host,string) identifiers. > > > Who? Who is proposing this? I never saw an email to SCSI Core about > this proposal? Is there any more information about this proposal > and what is the justification of it? Any specs and docs? No specs, just a comment from IRC. (host,string) could succeed in transporting both HCIL and non-HCIL target identifiers. Jeff