From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E7AE4C433EF for ; Wed, 20 Apr 2022 06:56:09 +0000 (UTC) Received: from localhost ([::1]:55454 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nh4G0-0005dc-VJ for qemu-devel@archiver.kernel.org; Wed, 20 Apr 2022 02:56:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46090) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nh4De-000489-Cx; Wed, 20 Apr 2022 02:53:42 -0400 Received: from verein.lst.de ([213.95.11.211]:42140) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nh4Dc-0006kl-Lq; Wed, 20 Apr 2022 02:53:42 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 1C37467373; Wed, 20 Apr 2022 08:53:35 +0200 (CEST) Date: Wed, 20 Apr 2022 08:53:34 +0200 From: Christoph Hellwig To: Klaus Jensen Subject: Re: [PATCH 4/5] hw/nvme: do not auto-generate uuid Message-ID: <20220420065334.GA3651@lst.de> References: <20220419121039.1259477-1-its@irrelevant.dk> <20220419121039.1259477-5-its@irrelevant.dk> <20220420053336.GA2063@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Received-SPF: none client-ip=213.95.11.211; envelope-from=hch@lst.de; helo=verein.lst.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org, Klaus Jensen , qemu-devel@nongnu.org, Luis Chamberlain , Keith Busch , Christoph Hellwig Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Apr 20, 2022 at 07:51:32AM +0200, Klaus Jensen wrote: > > So unlike the EUI, UUIDs are designed to be autogenerated even if the > > current algorithm is completely broken. We'd just need to persist them. > > Note that NVMe at least in theory requires providing at least on of > > the unique identifiers, and the UUID is the only one designed to be > > autogenerated in a distributed fashion. > > I understand, but it boils down to the fact that we do not have a > general method of storing "metadata" like this persistently. > > But maybe it is time that we come up with something to do this. If we can't make the persistent uniqueue identifiers persistent and unique, we should not provide them. While NVMe does require a namespace to report at least one of the three identifies, the failure mode for now having one is much more graceful than providing one that is not unique or not persistent.