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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16B4AC433DB for ; Fri, 19 Mar 2021 15:30:39 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 3E49B61939 for ; Fri, 19 Mar 2021 15:30:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E49B61939 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; 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=0aRdRaYVWdQTqIus5yoZwkWgCh6ZAnU+v8LSGVBDdNs=; b=QBFKLE9wVD4tn13kLE5sArOfZ EIVWm8mYTveoW63xL8bvH9Enx0mpCESRo8vD5uyCtQrfi7JvUHJh3rP9sZHZWyjefutENcv+HWOXg BN4lKsP85Mw/6+iWYCDnzaXDMgAldx3KYc0QRZ9D+BMNDAtPuDsnoSdEO1oo+ezsQHgYBu6wZtmMP H9DnihBrHPjIslwp1DuRT59bR6PTMkTbua/p9dsKH2tyHcZhj+BfP/TG9g/RkL37VkdIu/AXKROKt 9mu7ufsoquSdHI7x8vaqilqoknORwkE03i6iEkXx6So4oOeSCe0Kzoy09im7cR1VeYAB5EbvqmbN2 sR0WMeYjA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lNH4r-007dgk-Gg; Fri, 19 Mar 2021 15:30:17 +0000 Received: from verein.lst.de ([213.95.11.211]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lNH4n-007dfE-K0 for linux-nvme@lists.infradead.org; Fri, 19 Mar 2021 15:30:15 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 575D368BFE; Fri, 19 Mar 2021 16:30:09 +0100 (CET) Date: Fri, 19 Mar 2021 16:30:08 +0100 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , Alan Adamson , "linux-nvme@lists.infradead.org" , "axboe@fb.com" , "sagi@grimberg.me" Subject: Re: [PATCH 0/1] nvme: Export CSTS register via sysfs Message-ID: <20210319153008.GA14280@lst.de> References: <20210317204615.13971-1-alan.adamson@oracle.com> <20210318043828.GB26988@lst.de> <0D18CE6C-4390-4040-98A6-14204DE33253@oracle.com> <20210318165213.GA31675@redsun51.ssa.fujisawa.hgst.com> <0D017D65-3D7C-4165-B25B-21E6A6FFDED5@oracle.com> <20210318194653.GA2690@dhcp-10-100-145-180.wdc.com> <20210319065158.GA11263@lst.de> <20210319152208.GA3794@redsun51.ssa.fujisawa.hgst.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210319152208.GA3794@redsun51.ssa.fujisawa.hgst.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210319_153013_708174_4477BE52 X-CRM114-Status: GOOD ( 14.97 ) 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 Sat, Mar 20, 2021 at 12:22:08AM +0900, Keith Busch wrote: > > I think this is a horrible idea. Userspace has no business touching > > registers even read-only. MMIO reads can have side effects as well, > > intentional or unintentional, and we also open up a whole can of worms > > of mismatched memory attributes. > > I was thinking the driver wouldn't opt-in if there were read side > effects, but yeah, it's too fragile. I withdraw the suggestion. I'd still like to understand what values in CSTS Alan cares about. I don't think just dumping a register with somewhat awkward encodings is a good idea. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme