From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=43809 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OJmat-0004nx-J8 for qemu-devel@nongnu.org; Wed, 02 Jun 2010 07:58:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OJmap-0007f1-BH for qemu-devel@nongnu.org; Wed, 02 Jun 2010 07:58:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:18962) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OJmap-0007eg-59 for qemu-devel@nongnu.org; Wed, 02 Jun 2010 07:58:43 -0400 Date: Wed, 2 Jun 2010 14:54:30 +0300 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] Re: [PATCH] virtio-blk: assign a default serial number if none provided Message-ID: <20100602115430.GA29755@redhat.com> References: <20100602014854.GB16406@us.ibm.com> <20100602090050.GA19662@redhat.com> <20100602114546.GB19185@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100602114546.GB19185@us.ibm.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ryan Harper Cc: john cooper , qemu-devel@nongnu.org On Wed, Jun 02, 2010 at 06:45:46AM -0500, Ryan Harper wrote: > * Michael S. Tsirkin [2010-06-02 04:08]: > > On Tue, Jun 01, 2010 at 08:48:54PM -0500, Ryan Harper wrote: > > > This patch applies on-top of John's virtio-blk serial patches. > > > > > > Generate default serial numbers for virtio drives based on DriveInfo.unit which is > > > incremented for each additional virtio-blk device. This provides a > > > per-virtio-blk number to use in the default string: QM%05d that is used in > > > hw/ide/core.c. The resulting serial number looks like: QM00001, etc. > > > > > > Signed-off-by: Ryan Harper > > > > > > I think that there's a problem with this approach in that hot plug A, > > hot plug B, hot unplug A is not the same as hot plug B. > > So you might get guest boot failures and no easy way to > > figure out why. For guests that need S/N, I think they > > really must be persistent. > > That's true; though I think most boot drives boot via either LVM or UUID > which will remain persistent. That said, if you are relying on the > by-id; then of course the user will need to specify serial versus having > one auto-generated. I guess the question then would be, if you don't rely on the S/N, why do you want to set it? > -- > Ryan Harper > Software Engineer; Linux Technology Center > IBM Corp., Austin, Tx > ryanh@us.ibm.com