From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:53320) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QNTdn-00066v-L1 for qemu-devel@nongnu.org; Fri, 20 May 2011 13:37:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QNTdm-0002kb-En for qemu-devel@nongnu.org; Fri, 20 May 2011 13:37:35 -0400 Received: from mail-ww0-f53.google.com ([74.125.82.53]:35213) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QNTdm-0002kV-5C for qemu-devel@nongnu.org; Fri, 20 May 2011 13:37:34 -0400 Received: by wwj40 with SMTP id 40so3880766wwj.10 for ; Fri, 20 May 2011 10:37:33 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <4DD6A6DA.6040808@redhat.com> Date: Fri, 20 May 2011 19:37:30 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1305903817-25476-1-git-send-email-pbonzini@redhat.com> <20110520161436.GA5149@lst.de> In-Reply-To: <20110520161436.GA5149@lst.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH 0/6] SCSI series part 2, rewrite LUN parsing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: qemu-devel@nongnu.org On 05/20/2011 06:14 PM, Christoph Hellwig wrote: > I don't quite understand what you mean with path here. It doesn't > seem to map to any SAM concept, nor does it seem to be related > to traditional multipathing. It's what SAM calls a "bus identifier" in the description of LUN addressing modes. > Can you explain what a path is supposed to be, and why it's called a "path"? It's a SAM "BUS IDENTIFIER", but bus was too confusing with respect to qdev's BusState (which represents either a SAM bus identifier or target). I think the term "path" comes from Windows, see for example http://msdn.microsoft.com/en-us/library/ff564699%28v=vs.85%29.aspx: PathId [in, optional] Indicates the SCSI port or bus for the request. This parameter is optional. ... but I chose it because I found it also in SAM: "The BUS IDENTIFIER field identifies the bus or path that the SCSI device shall use to relay the received command or task management function". I might also call it scsi-initiator which is consistent from the idea that it sits between two targets ports. Paolo