From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56888) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLVDw-0008IS-MZ for qemu-devel@nongnu.org; Tue, 09 Oct 2012 04:31:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLVDq-00019q-34 for qemu-devel@nongnu.org; Tue, 09 Oct 2012 04:31:32 -0400 Received: from mail-bk0-f45.google.com ([209.85.214.45]:56543) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLVDp-00019Y-RY for qemu-devel@nongnu.org; Tue, 09 Oct 2012 04:31:26 -0400 Received: by mail-bk0-f45.google.com with SMTP id jf3so2100460bkc.4 for ; Tue, 09 Oct 2012 01:31:24 -0700 (PDT) Date: Tue, 9 Oct 2012 10:31:20 +0200 From: Stefan Hajnoczi Message-ID: <20121009083120.GA13775@stefanha-thinkpad.redhat.com> References: <20120921133031.GA1682@darkstar.nay.redhat.com> <505C768A.5070801@redhat.com> <20120923023709.GA2742@darkstar.nay.redhat.com> <20121005081458.GC1399@stefanha-thinkpad.redhat.com> <50738B8E.1080303@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50738B8E.1080303@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] virtio-blk: add default serial id List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dave Young Cc: qemu-devel@nongnu.org On Tue, Oct 09, 2012 at 10:27:26AM +0800, Dave Young wrote: > On 10/05/2012 04:14 PM, Stefan Hajnoczi wrote: > > > On Sun, Sep 23, 2012 at 10:37:09AM +0800, Dave Young wrote: > >> For the serial number decreasing issue, I think there's only these two ways to > >> select, there's no ideal way to resolve this issue. > >> My use case for this is for the kdump kernel to find proper disks, > >> after 1st kernel crashing 2nd kernel need find right disk to dump vmcore. > >> In this case v1 and v2 aproaches are both find to me. > >> > >> From my point of view, patch v1 is better though, I think unpluging 100000 is > >> not a sane use case. It's not likely to happen. > > > > I'm not sure auto-assigning serial numbers is a good idea. The guest can use > > the serial number in /etc/fstab or other places where it expects the serial > > number to be persistent. > > > > Your patch does not provide persistent serial numbers, so a change to the QEMU > > invocation could result in different serial numbers. The guest will get > > confused or perhaps refuse to boot. > > > Yes, it introduce confusion, but in this way at least the serial number > can be persistent across guest reboot. Traditionally ide disks use this > way as well, such as QEMU_HARDISK_00001, I think guest should not use > this in /etc/fstab. If you don't want to set a persistent serial number, use another mechanism to identify the disk. For example, Linux has /dev/disk/by-path/ which identifies virtio-blk PCI adapters, IDE, SCSI disks, etc. Does this work for your use case? Stefan