From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [RFC]: 64 bit LUN/Tags, dummy device in host_queue, host_lock <-> LLDD reentrancy Date: Mon, 26 Aug 2002 09:11:16 -0500 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <200208261411.g7QEBGS30369@localhost.localdomain> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: (from root@localhost) by pogo.mtv1.steeleye.com (8.9.3/8.9.3) id HAA22719 for ; Mon, 26 Aug 2002 07:11:31 -0700 In-Reply-To: Message from "Aron Zeh" of "Mon, 26 Aug 2002 10:02:47 +0200." List-Id: linux-scsi@vger.kernel.org To: Aron Zeh Cc: Luben Tuikov , linux-scsi ARZEH@de.ibm.com said: > To me all of the proposed changes look good. The one above I'd be > interested in particularly. It would help sorting out a lot of woes we > had with writing a fibre-channel HBA driver. For fibre-channel LUNs > and port IDs (WWPN) are 64-bit and depending on configuration, high > values can be (and in our case are) common. Actually, I'd like to see us moving towards adopting the capabilities of driverfs for this. PUN is to all intents and purposes now an abstraction in the FC realm. LUNs too, as long as they retain the grouping abstraction with PUNs. The mid layer really doesn't need to know what these are (there are a few pieces of code that populate the LUN field for SCSI-1 devices that would need rework). All the mid layer really needs is the Scsi_Device structure that describes an individual LUN (and some knowledge of LUN and PUN grouping for reset action prediction). It doesn't need to know or care about the current PUN and LUN numbers. If FC drivers move straight to using driverfs, you can populate the driverfs names with whatever is meaningful to you for PUN (WWN, portid etch) and LUN and thus avoid this problem (and also the mapping code most have to take these to and from the PUN/LUN numbers). Since driverfs is a tree, the PUN/LUN division is done in a directory (and could, theoretically be done on more than just a two level split). James