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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2827C433EF for ; Mon, 4 Oct 2021 09:42:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AF9B16124B for ; Mon, 4 Oct 2021 09:42:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AF9B16124B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=movementarian.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0DPw+FoM5xnyjbomX9fupGaW7Oce6ZRkWY8GnOnl5yU=; b=l3AqVcxnXkA17z 8nn1oRQl+LIyDUTXtoLeQ8FaFEyJoCMLui/gHq5BM4+XD+ix40JsDp1oIOvQIrhEq1/t74un7miKm GYKaXTbpP3MzEvM6o8NDckuiw/O/bMShJKUZcyHbRg/IpAEuOptsRtxDpL1IpbBKXmEt7eXnR0yhz KDVOnGznu07dDITJjhdFqv0sBu16Qh/gLoXB8mtxqwJC361OxPw9mIJ+EMV9teMxl3DUWk5hh1yGy Uup2ZSGfKjj1fQLzestnAFK/9/akSanQ3ORoIadMFQtcyu6hrtTzP/BzxEJb4ALVhPcqMfh0utiJY xIksn/kKpF8R7YHRN2FQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXKUT-005oXR-3Q; Mon, 04 Oct 2021 09:42:33 +0000 Received: from ssh.movementarian.org ([139.162.205.133] helo=movementarian.org) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXKUQ-005oWc-4D for linux-nvme@lists.infradead.org; Mon, 04 Oct 2021 09:42:31 +0000 Received: from movement by movementarian.org with local (Exim 4.94) (envelope-from ) id 1mXKUO-0002A7-Ug; Mon, 04 Oct 2021 09:42:28 +0000 Date: Mon, 4 Oct 2021 09:42:28 +0000 From: John Levon To: Keith Busch Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me Subject: Re: [PATCH 2/3] nvme-pci: remove cached shadow doorbell offsets Message-ID: References: <20200427235243.2268765-1-kbusch@kernel.org> <20200427235243.2268765-2-kbusch@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200427235243.2268765-2-kbusch@kernel.org> X-Url: http://www.movementarian.org/ X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211004_024230_196795_4C1C94B3 X-CRM114-Status: UNSURE ( 8.03 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Apr 27, 2020 at 04:52:42PM -0700, Keith Busch wrote: > And when this feature is in use, the specification requires all queue > updates use this mechanism, so don't don't treat the admin queue > differently. Also came across this patch of yours. We were wondering why Linux isn't spec compliant for the admin queues. But this would cause implementation difficulties for a controller, right? Currently we presume that the admin queue's shadow doorbells aren't valid, so always look at BAR0 location. It's unclear what we'd do if this change were made in Linux, presuming we need to support older Linux versions. Some hack that observes a non-zero shadow value and presumes the admin queue is using shadow doorbells? Thoughts? thanks john _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme