From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752203Ab2GZLbH (ORCPT ); Thu, 26 Jul 2012 07:31:07 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:49874 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298Ab2GZLbF (ORCPT ); Thu, 26 Jul 2012 07:31:05 -0400 Message-ID: <1343302260.3115.33.camel@dabdike> Subject: Re: [PATCH 1/2] virtio-scsi: fix parsing of hotplug/hot-unplug LUN number From: James Bottomley To: Paolo Bonzini Cc: Bart Van Assche , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Date: Thu, 26 Jul 2012 15:31:00 +0400 In-Reply-To: <50111F6C.7010502@redhat.com> References: <1342454751-8950-1-git-send-email-pbonzini@redhat.com> <1342454751-8950-2-git-send-email-pbonzini@redhat.com> <1343292731.3115.17.camel@dabdike> <50110820.4040403@redhat.com> <1343294472.3115.22.camel@dabdike> <50111936.8090508@acm.org> <1343298798.3115.31.camel@dabdike> <50111F6C.7010502@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-07-26 at 12:43 +0200, Paolo Bonzini wrote: > Il 26/07/2012 12:33, James Bottomley ha scritto: > >> > Has it already been considered to modify scsilun_to_int() such that LUN > >> > numbers start at zero even for addressing method 1 ? This is what e.g. > >> > the function scst_unpack_lun() already does. See also > >> > http://scst.svn.sourceforge.net/viewvc/scst/trunk/scst/src/scst_lib.c?revision=HEAD&view=markup. > > Yes, as I said before, the problem is that the actual numbers are > > > > 1. not 1:1: there are several possible encodings of luns 0-255 > > 2. hierarchical, so once you go beyond a single level you can't properly > > use a numeric representation either. > > > > the mid layer just uses the lun number as an encoding of the actual SAM > > lun. The key for us is that int_to_scsilun has to go back the other > > way. > > I still disagree, but I will modify QEMU so that this patch is not > necessary. Later I can switch to int_to_scsilun. Thanks, on the principle of least surprise, you definitely don't want the lun numbering to change depending on whether you directly attach to the array or pass it through virtio-scsi. James