From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 1/2] virtio-scsi: fix parsing of hotplug/hot-unplug LUN number Date: Thu, 26 Jul 2012 11:27:40 +0200 Message-ID: <50110D8C.8060802@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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1343294472.3115.22.camel@dabdike> Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org List-Id: linux-scsi@vger.kernel.org Il 26/07/2012 11:21, James Bottomley ha scritto: >> > Because scsilun_to_int does not do the AND, so it would have exactly the >> > same bug I'm fixing. > It's not a bug ... it's the encoding. All the other devices use this > too. Ideally we should have switched to 64 bit lun numbers for the > encoding to be exact, but nothing so far has gone over 32 bits. If we > don't encode the Address method as part of the lun number, we don't get > the reverse transform right and the addressing often fails. But virtio-scsi gets it right even if you use method=0 and method=1 interchangeably. ibmvscsi (see function lun_from_dev) does something similar to virtio-scsi, except here I need both directions. > That does mean that arrays that use address method=1 in REPORT LUNS have > their lun numbers start at 16384. That is ugly. I can see how it may be needed on buggy hardware, but here we know it's not. Paolo