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 8F6F3C43334 for ; Thu, 9 Jun 2022 20:05:04 +0000 (UTC) Received: from localhost ([::1]:34114 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nzOOt-0000uI-JC for qemu-devel@archiver.kernel.org; Thu, 09 Jun 2022 16:05:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33748) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nzMIL-0003hH-NM for qemu-devel@nongnu.org; Thu, 09 Jun 2022 13:50:09 -0400 Received: from ssh.movementarian.org ([139.162.205.133]:34152 helo=movementarian.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nzMIJ-000847-Fu for qemu-devel@nongnu.org; Thu, 09 Jun 2022 13:50:08 -0400 Received: from movement by movementarian.org with local (Exim 4.94.2) (envelope-from ) id 1nzMIC-005fvA-0k; Thu, 09 Jun 2022 18:50:00 +0100 Date: Thu, 9 Jun 2022 18:50:00 +0100 From: John Levon To: Klaus Jensen Cc: Keith Busch , Jinhao Fan , qemu-devel@nongnu.org Subject: Re: [PATCH 1/2] hw/nvme: Implement shadow doorbell buffer support Message-ID: References: <20220608013659.472500-1-fanjinhao21s@ict.ac.cn> <20220608013659.472500-2-fanjinhao21s@ict.ac.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Url: http://www.movementarian.org/ Received-SPF: pass client-ip=139.162.205.133; envelope-from=movement@movementarian.org; helo=movementarian.org 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_PASS=-0.001, SPF_PASS=-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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jun 09, 2022 at 07:27:57PM +0200, Klaus Jensen wrote: > > It's not just unnecessary, but enabling shadow doorbells on admin queues will > > actively break device implementations (such as SPDK), which have had to presume > > that driver implementations don't use shadow doorbells for the admin queue. > > I'm ok with following the concensus here, but we all agree that this is > a blatant spec violation that ended up manifesting itself down the > stack, right? Yup. I've been meaning to try following up to get the spec updated to reflect reality, but haven't made progress there yet. > So... if QEMU wants to be compliant here, I guess we could ask the > kernel to introduce a quirk for *compliant* controllers. Now, THAT would > be a first! Not sure if I am being serious or not here ;) :) regards john